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VOL. XLIV, NO. 517 JANUARY, 1910
THE
AMERICAN
NATFURALISI
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
Page
The Reappearance in the Offspring of artificially seer Parental Modi-
fications. Dr. FRANCIS B. SUMNER
A Bimodal Variation Polygon in Syndesmon thalictroides and its Morpho-
logical Significance. Dr. J. ARTHUR RIS 1
The Miocene Trees of the Rocky Mountains. Professor T. D. A. COCKERELL 31
A Suggestion regarding Heavy and Light Seed Grain. L. R. WALDRON . 148
Notes and Literature: Hammalogy—Nelson’s Monograph of the North American
Leporide, Dr. J. A. ALLEN. Pe re oe ane tiber den
Bau der nervosen Centralorgane, Professor G. H. Par
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THE
AMERICAN NATURALIST
Voit. XLIV January, 1910 No. 517
THE REAPPEARANCE IN THE OFFSPRING OF
ARTIFICIALLY PRODUCED PARENTAL
MODIFICATIONS !
DR. FRANCIS B. SUMNER
Woops Hore, Mass.
In a recent paper? I have described a series of experi-
ments conducted during the past few years upon white
mice. I have there shown that large enough differences
of temperature, operating throughout the period of
growth, bring about considerable, and in some cases
quite obvious, differences in the length of peripheral
parts (tail, foot and ear), and probably changes in the
quantity of hair as well. The peripheral parts were
found to be longer in the warm-room lots (12 to more
than 30 per cent. longer, in the case of the tail); the
amount of hair, on the contrary, was less. It was pointed
out, furthermore, that differences of precisely this sort
have long been known to distinguish northern from
southern races of mammals.
The question of most vital interest was not, however,
touched upon in the earlier paper, although it has fur-
nished my real motive for pursuing these experiments
throughout. Are these modifications purely transitory,
1 This rather cumpersome title has been chosen in order to forestall any
possible misrepresentation of my claims by those who do not read beyond
headlines. Note that I have used the word ‘‘reappearance,’’ rather than
‘*inheritance.’’
2 Journal of Experimental Zoology, August, 1909.
5
6 THE AMERICAN NATURALIST [ Vou. XLIV
that is to say confined to the generation immediately
affected, or do they reappear, if only to a slight degree,
in the offspring? I have long felt that satisfactory evi-
dence for or against the transmission of such modifica-
tions would be lacking, so long as zoologists confined
themselves to a search for directly visible qualitative dif-
ferences. With few exceptions, however, such has been
the method by which the problem has been attacked.
The following conditions must, I believe, be realized
before we may hope to attain to any satisfactory test
of this time-honored question: (1) We must select for
experiment such an organism and such a physical agency
that the latter may modify the former without directly
infinencing the germ cells. The action of temperature
upon a warm-blooded animal seems to realize this condi-
tion most fully. (2) We must discover readily meas-
urable, quantitative changes in the parent generation,
before we can hope to test the reappearance of such
changes in the offspring.
Having discovered such modifications in the parent
generation, there are theoretically two methods by which
we may attack the problem in hand. We may either (1)
raise the offspring of the experimental and control? lots
under identical conditions, or (2) we may raise the off-
spring of the modified parents under the same conditions
as were employed to effect the original modification. In
the first case, we should compare the two sets of animals
having different parentage. Assuming a given modifi-
cation of the value x, and supposing that 1/n represented
the proportional part of this to be transmitted, the off-
spring of the two lots would be found to differ by the
quantity x/n. If the second method were employed, we
should compare the second generation with the parent
generation, the two being measured at the same age.
* For the sake of simplicity I have here assumed that one lot was merely
a ‘feontrol’’ lot, i. e., exposed to normal or indifferent conditions. In
my own experiments, Kit, I have chosen conditions with a view to
modifying both sets of individuals in opposite directions.
No. 517] PARENTAL MODIFICATIONS 7
Assuming that the latter had been modified to the extent
x, the former, according to hypothesis, would be found to
be modified to the extent x + x/n; i. e., the effect of the
conditions would have been cumulative.
Now, as a matter of fact, I have attempted both of
these tests upon rather a large scale; but I have not yet
found the second one to be practicable, owing to the diffi-
culty, without special facilities, of repeating precisely the
same temperature conditions during the lives of two suc-
cessive generations. But the first test proved to be prac-
ticable, and has yielded the results which are summarized
in the ensuing paper. Since the full data are to be pub-
lished elsewhere in the course of the coming year, the
omission of certain important portions of the evidence
will, I trust, be condoned.
The parents of the mice to be discussed had been
divided, at the commencement of life, into two lots, which
were reared in separate rooms, differing widely in tem-
perature.* Prior to the time of the pairing, they had
been exposed to these conditions for an average period of
about six months. For reasons which I shall not here
state, the two contrasted groups (‘‘warm”’ and ‘‘cold’’
lots) were not transferred to a common room before
pairing.” Indeed, the females were not removed to such
a room until the time that each was discovered to be
pregnant. The discovery was made, on the average,
about five days before the birth of the young, i. e., about
two weeks after the actual commencement of pregnancy.
This circumstance is of possible importance in interpret-
ing the results obtained. On that subject, more anon.
From the time that pregnancy became apparent, the
mothers of the two lots were kept in the same room and
under conditions which were identical, so far as care could
make them so. Differences of temperature were partic-
ularly guarded against.
* Differing by at least 15° C., on the average. The exact figures are
not yet computed.
5 The differences in temperature between the two experimental rooms
were, however, very much reduced at this time.
8 THE AMERICAN NATURALIST [ Vou. XLIV
The young were measured at the age of forty-two days.
It was found to be impracticable to make certain of these
measurements satisfactorily without subjecting the ani-
mals to ether. They were not, however, killed at this
time. The weight, and the length of tail, foot and ear
were determined. The linear measurements were taken
with a graduated sliding caliper, indicating tenths of a
millimeter. In the case of foot and ear, two measure-
ments were made of each, the mean figure being em-
ployed in the computations.®
Of these mice, 286 survived to the age of six weeks;
there being 141 offspring of warm-room parents, belong-
ing to 33 litters, and 145 offspring of cold-room parents,
belonging to 30 litters. From this earlier series of meas-
urements the following gross averages were obtained:
Weight Tail Foot Ear
(grams) (mm.) (mm.) (mm.)
Cold-room descendants ...... 10.897 71.04 17.833 12.434
Warm-room descendants ....10.631 71.19 17.960 12.536
It will be seen at once that, although the offspring of
the warm-room mice average slightly less in weight,
they have slightly longer tails, feet and ears than the
offspring of the cold-room mice. These differences are
exactly such as were noted, on a larger scale, in the
parent generation. But such gross averages do not, in
themselves, mean very much. In each of the contrasted
groups are comprised individuals of widely different
size (the extremes were 6.5 and 19.3 grams). Our ma-
terial, therefore, is not at all homogeneous.
Accordingly, I have divided the animals into groups,
comprising individuals of approximately the same
weight.’ Herewith are presented in tabular form the
results of such an analysis.
From the table it will be seen that there are eleven
groups in which a comparison between warm-room and
*The average difference between the first and second reading of the
caliper was 0.19 mm. for the foot, and 0.12 mm. for the ear.
*In my complete table I have likewise dealt with the sexes separately.
Lack of space prevents this procedure here.
,
No. 517] PARENTAL MODIFICATIONS 9
cold-room descendants is possible. The mean tail length
for the former animals is greater in eight of these eleven
cases (exceptions starred); the mean foot-length is
greater in nine of the eleven cases; while the mean ear
length is greater in nine cases, and equal in one case.
Let us consider the likelihood that such results have been
obtained through ‘‘chance.’’ What are the probabilities
that, in tossing a coin, we shall throw ‘‘heads”’ or ‘‘tails’’
as many as eight times out of eleven? The chances
that we shall obtain as great an excess as this (on one
O Cr eae
| S 35 a |
Group =I 23 bo Tail. Foot. | Ear.
D a> D |
i | E |
6-6.9 { Cola 2 6. 55 59.00 16.950 | 11.900
gms. Warm 3 6.77 | 60.67 16.800* | 11.850*
7-7.9 Cold 12 7.57 | 61.91 +0.79|16.954 3-0.110 11.850 +0.076
gms. Warm 16 7.58 | 65.87 +0.51/17.319 +0. 082 12.037 +0.047
8-8.9 Co d 9 8.51 | 64.78 +1.23)17.356 +0. 110) 12.217 +0.054
gms. Warm 19 8.48 | 67.11 +0.45/17.642 +0. 052) 12.313 +0.054
9-9.9 Cold 23 9.41 | 68.65 +0.57|17.572 +0.069 12.311 +0.035
gms. Warm 18 9.51 | 71.29 +0.30)17.906 +0.041) 12.533 +0.034
10-10.9 Cold 32 | 10.51 | 71.47 +0.39/17.962 0.069) 12.491 +0.037
gms. { Warm 27 | 10.33 | 70.41*+-0.47|17.931*-+0.050) 12.559 --0.048
11-11.9 Cold 27 | 11.42 | 73.62 +-0.36/17.975 0.063) 12.534 +0.0 5
gms. { Warm 17 | 11.38 | 78.06*+-0.38/17.994 +0.057| 12.568 +0.085
12-12.9 Cold 16 | 12.46 | 73.37 +0. 66/17. oe +0.100 12.544 +-0.065
gms. { Warm 18 | 12.39 | 73.67 +0. 42) 18.122 +0.052 12.783 +0.053
13-13.9 Cold 14 | 13.31 | 74.54 +0.79 18.200 +0.094 12.629 +0.069
gms. { Warm 12 | 13.82 | 76.33 +0.46)18.504 +0.052) 12.842 +0.083
14-14.9 Cold 3 { 14.30 | 75.607 18.333 12.617
gms. Warm 21 14.20 | 77.00 18.725 12.700
15-15.9 Cold 2 | 15.25 | 79.00 18.825 12.750
gms. { Warm 6 | 15.40 | 77.33* 19.000 13.067
16-16.9 Cold 3 | 16.20 | 79.33 19.100 13.050
gms. Warm 3 | 16.37 | 83.00 19.217 13.050*
19-19.9 Cold 1 | 19.30 | 89.00 19.700 13.200
_ gms. | _ Warm | 9]
side or the other) are about 5 out of 22. This is admit-
tedly not a very unlikely happening. The chances that
nine of the eleven will be of one kind are about 1 in 15.
10 THE AMERICAN NATURALIST [ Vou. XLIV
|
ah l !
4
pO 7 La
fad ee Sar nl iat let B16
Pa ee ee
pits Cintas PSE A TW pane sana + Ba
— — p +---4 Q io T ;
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l i KA TE ee LECI be ae eee
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fi A Í i ie Oe ee EFJ
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HH H BEEEEEEEEEEEE EEE TEATE
CIEN VURAR ! | a eae i SEEE RA EREA i
Make). 2ae? ae footie tat ie ts toa! t 7: i I iea: a
FIG urves showing mean tail length in relation to the size of the
anima ja. pay heavier line (W) represents the condition in the offspring of warm-
room parents, the lighter line (C) shpat that in the offspring of cold-room
parents. Abscissas denote weight in gram ordinates denote tail length in
millimeters, The figures along the curves iaito the number of individuals in
each size-group.
Finally, the chances that we shall obtain as high a pro-
portion as nine out of ten of the same sort are only 2
in 93.
It must be borne in mind, however, that we have the
cumulative testimony of these three characters, all point-
= * The group in which the two contrasted lots showed an equal ear-length
: has been left out of account. This would correspond to the case of a coin
~ remaining poised edgewise. In our probability peta we have not con-
-o vore such 2 hop eee
No. 517] PARENTAL MODIFICATIONS 11
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t i f H i f i i es A
i ro AT 112 LE - the! ST Poe the. l Us
3 i E ! Tr. me eas SEN D
e z Curves showing mean foot and ear length. The upper line (W) in each
e is that s rage aie) condition in offspring of warm-room parents. For further
scoot see Fig.
ing in the same direction; i. e., we have 26 out of 33 cases
showing the same tendency. If we assume that these
parts vary quite independently of one another,® and if
we leave out of consideration the single ease of equality,
the probability of our obtaining such a large majority in
a purely ‘‘accidental’’ way is only 1 in 1,869. In most
of the practical affairs of life, we should reject such a
contingency as not worth considering.
°’ In reality, there is a certain E of correlation between them, the
This
extent of which has not been compute would render the das nees
somewhat greater than is here indicated.
12 THE AMERICAN NATURALIST [ Vou. XLIV
Thus far, we have treated these groups as of equal
value in our computations. From our table it will be
seen, however, that the groups differ greatly in respect
to the number of individuals comprised, and in respect
to the magnitude of the differences shown. I have com-
puted the probable errors of the averages for those
seven groups which are large enough to make this worth
while. Taking into account the three characters (tail,
foot and ear) for the seven groups, we have, accordingly,
twenty-one probable errors for each of the contrasted
sets (‘‘warm’’ and ‘‘cold’’). A little figuring shows
that in twelve of these twenty-one cases the difference
between two contrasted averages is two or more times
as great as the probable error of that difference; in one
case the difference is over three times its probable
error, and in three cases it is over four times its prob-
able error.° The significance of these facts will be
appreciated by any one familiar with statistical methods.
Diagrams (Fig. 1 and 2) have been constructed per-
mitting of a comparison between the two contrasted sets
of mice, with respect to the mean length of tail, foot and
ear, for each of the size groups. These curves explain
themselves, and further comment seems unnecessary.
The question naturally arises: How do these differ-
ences between the warm-room and the cold-room descend-
ants compare in amount with the differences- which
were shown by the parents as a direct result of the ex-
ternal conditions? Unfortunately, the data necessary
for a direct reply to this question are not at hand, since,
in the case of the parents of this particular lot, foot
and ear length were not determined at the age of six
weeks. I have at hand, however, a set of measurements
for a considerable number of mice (80 ‘‘cold’’ +
129 ‘‘“warm’’), which were subjected to substantially
Tt is important to note that in none of the exceptional cases (i. e.,
those in which the cold room descendants have longer peripheral parts)
is the difference between the averages as high as two times its probable
error. In one case it is practically equal; in another it is considerably less.
No. 517] PARENTAL MODIFICATIONS 13
the same temperature conditions as were these parents.
To determine the extent of the differences, we shall
consider, not the differences between the gross aver-
ages, for reasons already stated, but the average differ-
ence, within each size group, between the ‘‘warm’’ and
the ‘‘eold’’ figure. These mean differences, representing
the extent of the modification shown at the age of six
weeks by mice directly influenced by temperature are:
At Se ee ee 9.710 mm
OGG hl pO fee ee eee ee 0.7138 mm.
A a ew ee Clee es ve 0.2021 mm.
Corresponding figures for the warm-room and cold-
room descendants with which we have been dealing are:
TA Se ee 1.264 mm
Foot ocean a 0.1890 mm
BP E E e Eee ae 0.1281 mm
Comparing these two sets of figures, we find that the
difference in tail length is 13 per cent. as great in the
second case as in the first; the difference in foot length
is 26 per cent. as great, while the difference in ear length
is 63 per cent. as great! These figures are not offered
as expressing, with even a rough degree of approxima-
tion, the proportional part of these parental modifications
which is handed on to the offspring—even granting that
such a transmission occurs. The relative magnitude of
these three percentages is particularly surprising, in view
of the fact that the tail is the organ which responds most
decidedly to the temperature differences, while the ear
has been shown to be least affected.'! It might be argued
that the very plasticity of a part, which makes it so re-
sponsive to outside influences, might render it correspond-
ingly ill adapted to retaining such impressions perma-
nently.12, Such speculations are decidedly premature,
however. |
“In my earlier paper I even expressed doubt as to the significance of
those slight differences which I did find in the case of the ear. Further
observations have, however, lessened these doubts.
12 It must be pointed out that the tail is far more variable than either
the foot or the ear.
14 THE AMERICAN NATURALIST [ Vou. XLIV
Another set of measurements was made with this same
lot of mice when they reached the age of three months.
By that time the numbers had been considerably reduced
by death. There were at the later date 114 of the cold-
room descendants, and only 84 of the warm-room descend-
ants. The survivors all appeared to be in good health,
however.
In order to exclude the possible influence of suggestion
or unconscious bias in determining these rather delicate
caliper measurements, I adopted the plan of keeping
myself in ignorance as to the parentage of each mouse
until the latter had been measured.’
I shall not at present enter into as full an account of
these later measurements as of the first series. The
differences between the gross averages are even less to
be relied upon here than in the case of the earlier figures,
since the two contrasted lots differed much more in their
mean size. The warm-room descendants were some-
what the heavier of the two, having a mean weight of
19.45 grams, as compared with 18.56 grams for the other
lot. The body length was also somewhat greater for
the former (87.683 mm.) than for the latter (86.703 mm).
For statistical purposes, the animals have been grouped
in two different ways: (1) according to weight, as was
done previously, and (2) according to body length."
The latter method of grouping seems a much fairer one
than the first, for it is probable that. the length of the
appendages is correlated primarily with body length, and
only incidentally with weight. The single weight-groups,
it may be added, contained individuals which differed
from one another by as much as 4 or 5 mm. of body length.
To consider the second of these methods first, the ani-
mals were divided into groups, within each of which the
% The animals were put into separate small cages, each bearing an
identification mark upon the bottom. These cages were ‘shuffled’? by one
or another of my colleagues in the laboratory.
“The mice were killed at the time of these later measurements. For
this reason it was possible to determine the body length with accuracy.
This is not feasible with living animals, even when etherized.
No. 517] PARENTAL MODIFICATIONS 15
individuals differed by less than one millimeter in length.
Of these groups there are 15 which allow of a comparison
between cold-room and warm-room descendants. Now
the ‘‘warm’’ figures for tail, foot and ear are larger than
the ‘‘cold’”’ figures in 12, 11 and 10 eases out of the.15,
respectively. The chances for the ‘‘accidental’’ occur-
rence of such majorities (in either direction) are roughly
1 in 28, 2 in 17, and 3 in 10, respectively. The cumu-
lative improbability, as regards the three cases, is very
high, but the exact chances have not been computed.
The results to be derived from a consideration of the
weight groups need not be detailed here. It must be
stated, however, that the figures, although showing the
Same general tendency as those we have considered, are
not, in themselves, as convincing as were the earlier ones.
Indeed, when the size groups are broken up into sub-
groups according to sex, the figures, for the males, at
least, are somewhat equivocal.
Thus, while the results of these latter measurements
on the whole confirm the results obtained earlier in life,
they are not as striking as those, and, if taken by them-
selves, could not be regarded as demonstrative. This
is due, in part, to the fact that we are dealing with smaller
numbers of individuals. It is probably also due, in part,
to the principle of the ‘‘leveling down of initial differ-
ences,’’ concerning which I have had much to say in my
earlier paper. And lastly, it is possible that unconscious
bias in the use of the calipers may have somewhat exag-
gerated the differences shown in the earlier series of
measurements, although caution was taken to avoid this.'*
INTERPRETATION
Aside from delusion or deliberate prevarication on the
part of the writer, several interpretations of these re-
sults seem theoretically possible.
* The caliper scale was at all times invisible to me until the points of
the instrument were finally adjusted. Personally, I regard any such bias
in making these measurements as a but it ean not be rejected
as impossible.
16 THE AMERICAN NATURALIST — [Vou. XLIV
1. The differences may be due merely to ‘‘coincidence’’
or ‘‘aecident.’? The odds against such an occurrence
have been shown to be high. Indeed the cumulative im-
probability that all of these differences have been acci-
dental is enormous.
2. They might have resulted from a slight though
constant biasing of the measurements in favor of that
result which was caleulated to give the greatest personal
satisfaction. This possibility, which has already been
considered, has been excluded in the case of the second
series of measurements. |
3. Granting their genuineness, the differences may be
due, not to any specific influence (hereditary or other-
wise) which has affected the tail, foot or ear directly, but
to some general constitutional difference in the offspring
of the two sets of parents. In other words, these differ-
ences in the length of the peripheral parts may be corre-
lated with some constitutional difference of a very gen-
eral sort. In this connection, it must be admitted that
the offspring of the warm-room mice showed a very much
higher mortality (40 per cent. between the first and sec-
ond measurements) than those of the cold-room mice
(20 per cent.). The former were likewise somewhat
larger, on the average, when measured at the age of three
months. Thus there did exist some sort of a constitu-
tional difference. The possibility here considered can
not, therefore, be set aside. On the other hand, there is
absolutely no evidence in its favor.
4. An explanation closely similar to the last would be
that the general stage of development in one lot of mice
had been accelerated or retarded as compared with that
of the other. We know that the ears and feet of young
mice are relatively much larger than those of older ones.
It might be contended, therefore, that the warm-room
descendants were in a relatively more juvenile condition,
despite the fact that they were, on the average, no smaller
(larger, indeed, at the time of the later measurements). —
No. 517] PARENTAL MODIFICATIONS 17
Even this possibility can not be dismissed without a
hearing.
0. The offspring themselves, during their fetal life,
may have been influenced in some way by the differences
of temperature to which the mothers were subjected dur-
ing the first two weeks of pregnancy (see above). It is
obvious, however, that in a warm-blooded animal, the
fetus could not be directly affected by differences of tem-
perature as such. It would be curious, indeed, if the
parental modifications should be so closely paralleled
under these circumstances.
6. The germ-cells of the parents may have been so
affected by the external conditions to which the latter
were subjected that modifications resulted in the off-
spring similar to those which were produced in the par-
ents directly. This hypothesis has been invoked again
and again to account for a certain class of facts which
would seem at first sight to lend strong support to the
Lamarckian hypothesis, e. g., by Weismann and by Tower.
Such an explanation could not, however, be applied in the
present case without radical modification. For we may
again point out that in a warm-blooded animal differences
of temperature, as such, could not affect either the fetus
or the germ-cells to any appreciable extent.'* The sug-
gestion might be made, however, that the effects of tem-
perature, even upon the parent body itself, may not be
direct, but may be due to the formation of specific chem-
ical substances which, through the medium of the blood,
may be supposed to simultaneously influence the body
and the germ-cells. Such a hypothesis can neither be
proved nor disproved in the present state of our knowl-
edge, but it is perhaps the type of explanation which is
calculated to appeal most strongly to the biologist of
to-day. It may be pointed out, however, that if a mech-
1 Pembrey (Journal of Physiology, Vol. XVIII, 1895, pp. 363-379)
found the temperature of adult mice to remain constant at widely different
external temperatures. In the young, however (under ten days old), the
body temperature was found to vary with that of the atmosphere.
18 THE AMERICAN NATURALIST [ Vou. XLIV
anism exists whereby the germ-cells may be so influenced
as to bring about the parallel modification of parent and
offspring, such a mechanism would be of exactly the same
value for evolution as the ‘inheritance of acquired char-
acters” in the old sense. For heredity, however, the
case would be different. We should still be able to go
on talking about the ‘‘continuity of the germ-plasm,”’
though that expression would have been shorn of much
of its meaning.
7. Finally, we have the view that the changes under-
gone by the parent body are in some way registered in
the germ-cells, so as to be repeated, in a certain measure,
in the body of the offspring. The ‘‘classical’’ attempt to
make this process intelligible is of course Darwin’s hy-
pothesis of ‘‘pangenesis.’’ Other views have been put
forward recently’? which are scarcely to be distinguished
from the preceding type of explanation (no. 6).
It would not be profitable to enter into any scholastic
discussion of these various hypotheses. One after an-
other of these alternatives must be excluded by carefully
planned experiments; and it is the intention of the present
writer to continue such experiments on a much greater
scale in the near future.
November 6, 1909.
“E, g., by Cunningham, Archiv fiir Entwicklungsmechanik, 1908.
A BIMODAL VARIATION POLYGON IN SYN-
DESMON THALICTROIDES AND ITS
MORPHOLOGIL SIGNIFICANCE
DR. J. ARTHUR HARRIS
CARNEGIE INSTITUTION OF WASHINGTON
In the spring of 1906 I had occasion to count the num-
ber of leaf Jaminz in the involucres of a series of four
hundred inflorescences of Syndesmon thalictroides col-
lected from the north slope of a hill at Meramec High-
lands, Missouri. In making the records, each distinct
lamina was counted, whether it was leaf or leaflet, the
immediate purpose of the work being to get some idea of
the variability in the number of divisions of the leaf sur-
face in the involucral whorl and the degree of interde-
pendence of the number of laminew and the number of
flowers for comparison with studies already made of the
correlation between length of stalk and number of flowers
per umbel in Nothoscordium and Allium,’ and between
number of flowers per inflorescence and number of ovules —
or seeds per ovary in Cercis? and Celastrus.? When I
gathered the material I was quite aware that this rough
method of lumping the lamine is not suited to bring out
the morphological significance of the data, but only a
little time was available for the work and for the purpose
then in hand the method of treatment seemed quite ade-
quate.
These data are shown in the form of a correlation sur-
face in Table I.
It is quite unnecessary to publish graphs for these two
distributions to show the conspicuously bimodal char-
acter. For the number of laminæ, there are conspicuous
1 Harris, J. Arthur, Ann. Rept. Mo. Bot. Gard., Vol. XX, 1909.
* Harris, J. Arthur, Biometrika. In pre
* Harris, J. Arthur, Ann. Rept. Mo. Bot. “Lied, Vol. XX, 1909.
19
20 THE AMERICAN NATURALIST [ Vou. XLIV
modes on 4 and 6, and for the number of flowers, pro-
nounced modes on 1 and 3.
Bimodal and multimodal polygons have received
much attention in the literature of variation that the in-
terest of a more detailed investigation was at once appar-
ent. Before considering further our data on this species
we may note the more important discussion of these
anomalous frequency distributions.
TABLE I
TOTAL LAMINA AND TOTAL FLOWERS PER INFLORESCENCE
Flowers per Inflorescence
ees A Se SUAS, ley | ae DAE eT cal
|
1 1 ose ah = 1
x 2 | 1 aie a —_ 1
LS 3 4 1 | 1 — 6
gS 4 38 25 | 47 a 110
2 5 | 9 18 | 28 he 55
Fe 6 ae n o o 2 218
SE | 1 1 od 8
8 | — _ | s E 1
Totals. | 90 69 [> 5286 | 7 100 5s
Bateson! gives a bimodal variation polygon for the
length of horns in the beetle Xylotrupes gideon and the
length of the forceps in the earwig, Forficula auricularia,
but the factors underlying the phenomena are not demon-
strated. Naturally the first suggestion concerning a
bimodal or polymodal polygon is that there is taxonomic
heterogeneity in the material examined. Davenport and
Blankenship® have even suggested criteria for determin-
ing whether the component elements of a two-humped
curve are to be designated as ‘‘varieties’’ or ‘‘species.’’
So far as I am aware the first attempt to analyze a bimodal
polygon into its component elements is that of De Vries?
t Bateson, W., ‘‘ Materials for the Study of Variation,’’ pp. 37-42, fig.
2-3, 1894.
5 Davenport, C. B., and J. W. Blankinship, Science, N. S., Vol. VII,
pp. 685-694, 1898.
€ De Vries, H., Archiv für Daa iongan Anak, Vol. II, 1895; also
Ber. Deutsch. Bot. Ges., Vol. XVII, pp. 84-98, 1899; also ‘‘Die Mutations-
theorie,’’ Vol. I, pp. 526-529; Vol. II, p. 349.
No. 517} A BIMODAL VARIATION POLYGON 21
with Chrysanthemum segetum. Pearson’ in the first of
his ‘‘ Mathematical Contributions to the Theory of Evo-
lution’? deals with the mathematical analysis of com-
posite frequency curves.
Dimorphism referable to peculiar environmental con-
ditions has received considerable attention, but unfor-
tunately quantitative data are not numerous. For
seasonal dimorphism in Idotheea, Gadzikiewicz* has pub-
lished some figures which yield very different polygons
for the body length of September and March females.
The above cases are illustrative merely and make no
pretense at completely setting forth the literature.
Ludwig and his pupils have devoted a whole series of
papers?’ to the discussion of multimodal variation poly-
gons. De Vries in ‘‘Die Mutationstheorie’’ lays con-
siderable stress upon the Fibonacci series. More re-
cently Ritter’ and Heyer’! have taken up the questions
and the reader should consult these papers for a full
statement of the problems and the pertinent literature.
In any discussions in this field, the warnings set forth in
papers by Pearson? and by Pearson, Yule, Tower and
Leet? on the sources of apparent polymorphism in plants
should always be kept clearly in mind.
Here I do not care to discuss the work of those who con-
clude that frequency curves have modes where they
™ Pearson, K., Phil. Trans. Roy. Soc. Lond., A., Vol. CLXXXV, pp. 71-
110.
s Gadzikiewiez, Bull. Acad. Sci. St. Petersb., Vol. XXIV, pp. 263-272,
1406; also Biolog. Centralbl., Vol. XX VII, pp. 505-508, 1907.
‘he com re bibliography of this work is quite out of place here. The
reader may consult F. Ludwig, Biometrika, Vol. I, pp. 11-29, 1901, for a
general Sii of some of Ludwig’s own views. See also citations by
Ritter.
r Ritter , G., Beih. Bot. Centralbl., Abth. II, Vol. XXII, pp. ie ip
1907 ; Abth. E Nol XXIII, pp. 273-319, 1908; Abth. I, Vol. XXV, pp.
29, 1909. Rather full citations of the Literature are given in these papers.
u Heyer, A., Biometrika, Vol. VI, pp. 354-365, 1909.
12 Pearson E Biometrika, Vol. I, pp. 260-261, 1902.
™ Piaron. k. G. U. Yule, W. Tower and A. Lee, Biometrika, Vol. 1,
pp. 304-319, 1902. See also a note on a paper ies Shull, Biometrika, Vol.
14, pp. 113-114, 1902.
2 THE AMERICAN NATURALIST [Vou XLIV
would be expected in accordance with some mathematical
series. It is obvious to any one trained in working with
numbers that there are serious difficulties in the way of
demonstrating a number of modes in a frequency distri-
bution. The errors of random sampling can not be dis-
regarded and when the variation is continuous instead of
discrete the chances of errors due to biased judgment
are great. These facts emphasize the necessity for
seeking out the simplest possible cases of polymorphism
and determining in so far as possible the morphological
conditions which underlie them. Such a case seems to be
offered by the involucral leaves of Syndesmon.
After I had made my first series of countings a paper
by Kellerman't giving the essential morphological fea-
tures of the leaves and considerable statistical data con-
cerning their variation came to my notice. He does not
present his data in a form suitable for statistical con-
sideration, and did not note the bimodal condition which
appears where a curve is plotted for the entire number
of lamine.
Kellerman’s diagrams represent the morphology of
the inflorescence very well and are reproduced here with
such additional ones as are necessary to represent the
types of leaves observed in our series. The terminal and
axillary buds which may develop into flower-bearing axes
are represented by solid dots. The number of leaflets
into which a leaf is divided is indicated by the partial
division of the line representing the leaf. Unfortunately
Kellerman’s data are rather too few to be given further
statistical analysis. For figures illustrating the general
appearance of different inflorescences the reader may
consult his plate.
Most simply the inflorescence consists of a terminal
. flower, two involucral leaves and two axillary flowers.
The axillary buds do not always develop. The leaves
may be entire or divided into (generally) three leaflets.
The form of inflorescences with two leaves, one ter-
“ Kellerman, W. A., Ohio Nat., Vol. I, pp. 107-110, 1901.
No. 517] A BIMODAL VARIATION POLYGON 23
minal flower and two axillary flowers is shown in Figs. 1
to 5. In our series we find all cases from those with both
leaves simple to those with both leaves ternately com-
pound.
C
f
p
6 5 Š 3 A
wA
Inflorescences of Seq.
In the next group of inflorescences an extra leaf is
added. The additional axillary bud thus introduced
raises the normal number of pedicels to four. Among the
inflorescences with a whorl of three leaves I found none
in which at least one of the leaves was not ternately com-
TABLE II
FREQUENCY OF DIFFERENT TYPES OF INFLORESCENCES WITH 2 LEAVES
Class. | f | Class.
1—1—8 (3) 1 an 2-8 (5) 13
<18 (2) 0 | 3—2—8 (2) T
1—1-—8 (1) 1 | 3—2—8 (1) 11
Fig. 1 | ig. 4
2—1—3 (3 0 I| 3—3—8 (3) 297
Low J (2) | 3—3—8 (2) 95
2—1—8 (1) | 1 | 3—3—8 (1) 74
Fig. 2 ee 6 |
3—1—8 (3 | e re
9 j- H | 16 Total. | 544
1) | 17 |] |
24 THE AMERICAN NATURALIST [ Vou. XLIV
pound, but in three of them two of the leaves were
simple. The different normal types observed are made
clear by diagrams 6 to 10.
TABLE III
SENTIT OF DIFFERENT TYPES OF INFLORESCENCES WITH 3 AND 4 LEAVES
Class. | f aa Class
etd (4) 2 B—8—2—4 (5)38 1
$--J—1—4 (8) 'l 3-3-3724 74) 4
Sred (2 Gas $—8-9-—# (+) 0
$- 1-1-4 (1) eee 4-3-2-4 £2} 1
Fig. 6 $994 17) | 0
ne Td (4) 1 Fig. |
1-4 '(38) 0 r] 3-3 3-4 (4) | 6
3—2—1—4 (2) Back 9-858 —4 (8) 5 | 2
3—2—1—4 (1) 1 | 3—3—3—4 (2) 0
“T | $934 (1) 0
3-3-1 E (5) te: Fig. 1
S821 @ (4)17 76 =
Bi Genbank (8) 45 | Total. 137
Fole (3) 7 | esisto
ymas a e CEERI 1
| Fig. 1 |
| | $2 3-92 b (É) 1
| Fig. 12
| 8—8—8—1—6 (3) 1
| i} g. 13
| | Total. | 4
Finally, four leaves with the possibility of four axillary
pedicels may be found. The condition of the division of
these leaves into leaflets is shown in Figs. 11 to 13.
3 We may note four slightly abnormal inflorescences of the 3—3—3 type.
In one there was concrescence of the terminal and one axillary pedicel for
some distance from the base. In another one of the axillary peduncles bore
a lateral leaf. In a third the central of the three leaflets of one of the
leaves was again divided into three secondary leaflets. In the fourth ease
the two leaves were not opposite, as is usually the case, but were considerably
separated on the axis.
* In one of these three cases two peduncles are produced from one of the
axils. In the other two, one of the axillary pedicels bears a leaf subtending
a secondary pedicel bearing the fifth fruit
1 In one of these 76 cases the fourth fewer is due to one of the lateral
pedicels bearing a leaf in the axil of which a secondary pedicel is borne;
one of the axillary buds produces no flower in this case. In two other cases
one of the axillary pedicels bore a leaf, but no pedicel was produced in its
axil. In one of these cases one of the three leaflets—a lateral one—was
again divided into two. secondary leaflets.
* The fifth flower is due to two axillary pedicels being produced from one
of the leaves.
No. 517] A BIMODAL VARIATION POLYGON 25
Certain ‘‘teratological’’ cases are not represented by
figures, but are described merely.
We may now turn to the important question of the fre-
quency of the several morphological types in the Cold
Spring Harbor collection made in the spring of 1909.
In classifying these inflorescences all which were in-
jured in any way so that the number of primary divisions
of the leaf could not be made out with certainty were dis-
carded. Especial care was used in cases in which a leaf
was apparently divided into two leaflets, since such often
results from the breaking off of one of the lateral leaflets
of a ternately compound leaf. In some cases inflores-
cences were included in which the lamine of the primary
leafiets were not intact, so that the data can not be trusted
for the frequency of secondary divisions. In counting,
only completely divided laminæ were considered as
leaflets.
Petiolate leaves were not infrequently found, but no
special record was kept of them.
The data are set forth in minutely analyzed form in
Table II-III. The light-faced numbers separated by
dashes represent the number of primary leaflets into
which the leaves are divided. The black-faced numbers
show the number of flower-buds—terminal and axillary —
which might normally have developed, and the number
immediately following in parentheses shows the number
actually developing. The f (= frequency) column gives
the number of occurrences of each type.
Grouping the data according to the number of leaves
per inflorescence, we find:
Two leaves, in 544 cases.
Three leaves, in 137 cases.
Four leaves, in 4 cases.
685 altogether.
Here is an example of what De Vries!® has termed a
half-Galton curve. Whether it would be possible to in-
crease the number of leaves by selection as De Vries was
” De Vries, H., Ber. Deutsch. Bot. Ges., Vol. XII, pp. 197-207, 1894.
26 THE AMERICAN NATURALIST [ Vou. XLIV
able to do in the case of the petals of Ranunculus could
only be determined by direct experiment. Possibly the
skew curve here found is merely due to the age or vigor
of the individuals.
Considering next the distribution of the number of
primary leaflets per leaf in the material we may seriate
the number of leaflets for each class of plants separately,
as in Table IV.
TABLE IV
NUMBER OF PRIMARY LEAFLETS PER LEAF IN LEAVES FROM ALL DIFFERENT
LASSES OF INFLORESCENCES
Leaves per Inflorescence
T a aa 4 ane
|
eee a 49 126 6 181
S332. 34 8 1 43
a3 | 1005 277 9 1291
Totals. | 1088 411 16 1515
Only sixteen leaves were available for the inflorescences
producing four leaves, but for those with two and three
leaves the number is ample. In each of the three classes
of inflorescences, and in the total, there is a pronounced
mode on undivided leaves and on those with three leaflets.
Throughout, those with two leaflets are much less fre-
quent than those with either one or three.’
Reducing the frequencies for the inflorescences with
two and three leaves to a percentage basis for more
direct comparison, and laying them side by side in Figs.
14 and 15, we note at once that there is a wide difference
in the proportion of single leaves in the two series. The
source of this difference is at once clear. In the inflores-
cences with the third leaf, the additional leaf is nearly
always simple. Thus the proportion springs at once
from about 4.5 per cent. to 30.5 per cent.
Unfortunately, our data, though extensive, are not
numerous enough to permit of further analysis. If ma-
terial were more ample it might be possible to ascertain
more precisely some of the factors determining the con-
No. 517] A BIMODAL VARIATION POLYGON 27
= dition of division of the leaf. All that we can conclude
from the present data is that: (a) There is a strong tend-
ency to the production of either simple or ternately com-
7 2 3 , 2 3
Fig. 14. Fie. 15.
pound leaves—those divided into two leaflets are rare;
(b) a larger proportion of the leaves are simple in inflo-
rescences with three or four leaves than in those with but
two leaves.
To determine whether the distribution for number of
leaf laminæ per involucre in this series forms a bimodal
distribution similar to that found in 1905, I extract the
totals from the two tables of data. To ascertain more
accurately the real source of the bimodal condition,
should it be found to exist in this series, the combinations
which give rise to the different total numbers are given
in Table V
From these figures appear several points which could
not be determined at all on the lumped data as collected
in te
28 THE AMERICAN NATURALIST [ Vou. XLIV
The grand total shows that there is a slight empirical
mode on four and a conspicuous one on six lamine, as
compared with the very prominent modes on these two
grades in 1905. The distributions from the three classes
of inflorescences shows the origin of these modes very
clearly. The mode on four is due entirely to the tendency
to the production of one ternately compound and one
simple leaf. Both of these types of leaves have been
shown to be much more frequent than those divided into
two leaflets. The mode on six is due to both of the in-
volueral leaves bearing the modal (three) number of
leaflets.
TABLE V
SHOWING THE FREQUENCY AND MODE OF ORIGIN OF THE DIFFERENT TOTAL
NUMBERS OF LAMINZ PER INFLORESCENCE
Laminæ of Individual Leaves
Two Leaves. | Three TENS D Four Leaves.
| | | ‘es ee ere > 7 Grand
TUS TT) 2 iaidigioit) 2 aii tigi
Se ee ak ww ce Tier Pee
| | | He | | [ojojo] |
ee je a a ea e GSEGRE |—|—-—| a
e Bel kooo | | ees
wee 8j T | ae | os
#2 4| a ct a | oo
EET beer nla eee bce oe
a6 | 466 466 | | 2 | Bete, | | 468
Sau | | ns | {118 | Bae...
$88 Be | = | 612 eee
EAr arai tibi
M a ea] Li esd a E
213 [a2 EA 3 |2118 6!8|137;21/1/1|4 | 685
In the 1905 series inflorescences with seven leaflets
formed only 2 per cent. of the population; in the 1909 lot
they are over 17 per cent. of the total number. There is
no way of determining absolutely why there is such a
difference, but it seems quite logical to suppose that in
the Cold Spring Harbor series inflorescences with three
leaves were much more abundant than in the Meramec
Highlands lot, for the frequency of seven laminæ in the |
Cold Spring Harbor material is entirely due to flower-
ing stalks with three leaves of which two are ternately —
compound and the third undivided.
No. 517] A BIMODAL VARIATION POLYGON ` 29
In the 1905 series all the laminæ found in the inflores-
cence were included in the countings. In the discussions
just given I have treated only the primary leaflets. The
data for the other lamine are included in the notes on the
tables of data or in the notes on teratological cases.
Their addition would make little difference in our distri-
butions, but the data are available for any one who cares
to use them.
TABLE VI
SERIATION OF NUMBER OF FLOWERS DEVELOPING IN DIFFERENT TYPES
OF INFLORESCENCES
Leaves per Inflorescence
2 3 4 Totals.
ee: 104 18 — 122
5S2 120 8 — 128
F553 320 18 | 2 340
eed | ie 89 | — 89
BF 5 | —_ 4 | 2 6
| 544 37 | 4 685
Further analysis of the data for leaf characters is not
justified by the quantity of material. Two conclusions
are seen to be amply justified by the facts: (a) In Syn-
desmon there is a strong tendency to the production of
simple and trifoliate leaves. (b) The preceding fact,
taken in connection with the peculiarities of the inflores-
cence with regard to the number of leaves produced, is
quite sufficient to account for the bimodal condition of the
variation polygon for number of laminæ per inflorescence.
The bimodal polygon is therefore explicable on purely
morphological grounds without any assumption of the
mixture of two or more ‘‘races’’ or ‘‘minor species,’’ pro-
vided the plants producing two, three and four leaves
per inflorescence be not considered ‘‘small species’’ or
‘*hiotypes.’’ Personally I see no reason whatever to
think that they are, but in these days of minute segrega-
tion the possibility must not be left unmentioned. To me
it seems not unlikely that the three different classes of
30 THE AMERICAN NATURALIST [ Vou. XLIV
inflorescences noted are to some extent to be referred to
age differences in the individuals producing them.
The number of flowers developing may now be tabu-
lated for each of the three classes of inflorescences. The
results are given in Table VI.
Here the bimodal condition in the number of flowers
per inflorescence found in the 1905 series does not appear,
although the frequency of inflorescences with one flower is
about as great as that of those with two. Doubtless the
reason for this difference would be clear if we had as
complete information concerning the 1905 series as is
available for the 1909 material.
The purpose of the present note will have been fulfilled
if in addition to the recording of a mass of definite quanti-
tative data concerning the form of the inflorescence in
Syndesmon, it convinces students of variation of the im-
portance of a critical consideration of purely morpholog-
ical features before concluding that an empirical multi-
modal polygon indicates the existence of biotypes.
COLD SPRING HARBOR, L. I.
THE MIOCENE TREES OF THE ROCKY
MOUNTAINS
PROFESSOR T. D. A. COCKERELL
UNIVERSITY OF COLORADO.
THe living arborescent flora of the Rocky Mountain
region is at the present time occupying the attention of
a number of able workers, including Nelson in Wyoming,
Rydberg of the New York Botanical Garden, Sudworth
of the Forest Service, Ramaley, Bethel and Schneider in
Colorado, Wooton in New Mexico, and others. As a re-
sult of all this activity, we are promised two manuals of
Rocky Mountain botany, and a third of trees alone, so
we shall have three separate and independent treatments
of our woody flora to compare and choose from.
Unfortunately, those who have been so active and ex-
haustive in their investigations of the living flora have
not cared, as a rule, to consider the historical or paleo-
botanical side of the subject. Many ‘‘recent’’ botanists
seem to have a positive dislike for fossil plants, and few
manifest any great eagerness to receive information
about the ancestors or predecessors of the species which
occupy their attention. Like all enthusiasts, the writer
is filled with the idea that the matter has only to be ade-
quately presented to command universal attention; and
hence offers this discussion, not so much for the paleo-
botanists as for those students of living plants whose
active interest may be aroused in the problems involved.
Going back from the present time, we are practically
without information concerning the plants of our region
until we come to the Florissant beds, assigned to the
Miocene. These beds, however, contain an abundant
series of remains, many of the plants beautifully pre-
served, as the accompanying illustrations show. They
testify to a climate both warmer and damper than that
of the present day, the arborescent genera including
Sapindus, Ficus, Diospyros, Persea, Leucena, Anona,
1 The determination of Ficus is based on the leaves. In confirmation of
31
32 THE AMERICAN NATURALIST [Vou. XLIV
ete., but so far as known no palms. Some, as Ailanthus
americana, pertain to genera now restricted to Asia.
The determination of the age of the Florissant beds
has been a matter of some difficulty, notwithstanding the
large number of organisms preserved. Comparing the
flora with that of the European Tertiary, I have felt
satisfied that it should be referred to the Miocene, and
probably to the Upper Miocene. The resemblance to the
flora of Œningen in Baden, known to be upper Miocene,
is most striking. Thus we have the oe parallel
or representative species:
Florissant. (Eningen.
Liquidambar convexum Cklil. Liquidambar europeum A. Br.
Ulmus braunii Heer, Lx. Ulmus braunii Heer.
Comptonia insignis (Lx.) Ckll. Comptonia œningensis A. Br.
Porana speirii Lx. Porana ceningensis A. Br.
Porana tenuis Lx. Porana macrantha Heer.
Acer florissanti Kirch. Acer tricuspidatum A. Br.’
Many others could be cited. On the other hand, the
Florissant incense cedar, Heyderia or Libocedrus colo-
radensis Ckll., is to be compared with H. salicornioides,
of the Lower Miocene of Radoboj in Croatia. The
Florissant redwood, Sequoia haydeni (Lx.), is not related
to S. sternbergi Heer from (Eningen, but to S. langsdorfii
(Bret.) Heer of the Swiss Lower Miocene; this species,
however, survived into the Upper Miocene in Italy and
Galicia. This S. langsdorfii has been recognized in
America also from the Upper Cretaceous to the Miocene,
and some of the Florissant specimens have been referred
to it; but the identity of the plants from so many diverse
localities and horizons is questionable, and from Floris-
sant I think we have only one species, S. haydent.
The Sequoia and Libocedrus of Florissant are both
very closely related to their living Californian allies; so
it comes a discovery by Mr. Brues, who in working over the parasitic Hymen-
optera from Florissant has come upon what appears to be a genuine fig-
insect, apparently of the South American genus Tetra Mayr.
* Acer trilobatum (Sternb., 1825) A. Br., 1845; not A. trilobatum. Lam.,
1786.
No. 517] MIOCENE TREES 33
much so that one is in some difficulty to point out any
tangible differences. This is equally true of a number
of other cases, of which the following are illustrative:
Florissant. Living.
Pinus wheeleri Ckll. Pinus flexilis James.
Pinus sturgisi Ckll. ' Pinus teda L
Ailanthus americana Ckll. Ailanthus glandulosa L.
Sambucus newtoni Ckll. Sambucus arborescens Nutt.
Anona spoliata Ckll. Anona glabra
Robinia brittoni Ckll. Robinia pseudacacia L.
-= Populus lesquereuxi Ckll. Populus angustifolia James.
Quercus lyratiformis Ckll. Quercus lyrata Walt.
Sapindus coloradensis Ckll. Sapindus drummondi H. & A.
So numerous are the resemblances to the living flora
that one might well feel persuaded to refer the beds to
the Pliocene—certainly better there than to the Oligocene
or Eocene! However, the Florissant fishes, with the
exception of Amia, are of extinct genera, and no less
than 178 genera of insects are supposed to be extinct.
For a variety of reasons, based chiefly upon a study of
the insects, I believe that the Florissant period corre-
sponds with Osborn’s ‘‘Fifth Faunal Phase’’ (Bull. 361,
U. S. Geol. Survey), in which a new fauna was invading
the country from Eurasia, while connection with South
America had not yet been established. Some of the
Florissant groups of insects, such as the Aphidide and
Bombyliide, seem to represent the original American
fauna uncontaminated; while others show old world
types, the most significant and interesting of which is
the tsetse fly (Glossina).2 Osborn’s ‘‘ Fifth Phase’’ in-
cludes the Middle and Upper Miocene, and so far as may
be judged, Florissant should belong near the middle
of it.
The attempt to correlate the Florissant beds with other
American floras ascribed to the Miocene brought out a
number of difficulties. With the exception of the little-
3 A second species of tsetse fly, Glossina osborni Ckll., has been recently
diseovered. It is only 104 mm. long, the wing 7 mm.; the venation is normal
for the genus, but the first basal cell bulges less subapically than in Seud-
der’s species.
34 THE AMERICAN NATURALIST [Vou. XLIV
P -
Fig. 2. Weinmannia lesquereuxi Ckll. Fic. 1. Weinmannia phenacophylla_Ckll.
known formation at Elko Station, Nevada, I do not find
anything-which really seems to correspond with Floris-
sant. According to the theory outlined above the Mascall
beds of Oregon, which possess a varied flora, should be
either contemporaneous ‘or (more probably) somewhat
earlier. Fortunately, fourteen-species of mammals have
been obtained from the Mascall, and these place it rather
definitely in the Middle Miocene. Considering, therefore,
a probable moderate difference in time, combined with
noteworthy geographical and altitudinal differences, we
ought to find the Maseall flora similar to, but by no means
identical with, that of Florissant; and this is exactly what
comparisons show.
Thus of the 77 Mascall plants (nearly all trees) re-
ferred to definite genera, no less than 56 are congeneri¢
with those of Florissant. Of those not congeneric, five
are so dubious that they have not been specifically deter-
mined. The Mascall genera not yet found at Florissant
are the following:
1. Equisetum.—This has no significance, as it abounds
in Colorado to-day, and must have been present during —
the Florissant period.
= Ee i; a ; APEN EE EEE A
3 4 ga Ai
o e E n a a e a a aa s TLT aa aaa a A e aaa = s
|
No. 517] MIOCENE TREES 35
2. Ginkgo.—Represented in the Maseall by a fragment
-not specifically determined. This genus is not known
in the Rocky Mountains later than the Laramie and Liv-
ingston, on the border line between the Cretaceous and
Tertiary. As is well known, there is a single living
(Asiatic) species.
3. Thuites.—A fragment not specifically determined.
It is practically identical with T. ehrenswdrdi Heer
(Miocene of Sachalin and Spitzbergen), but that plant
appears to be referable to the modern genus Chamecy-
paris.
4. Glyptostrobus.—A genus still living in China. It
was supposed to occur at Florissant, but I believe the
material so referred all belongs to Sequoia. The Maseall
material is not above suspicion of also being Sequoia;
indeed Lesquereux so referred one of the specimens.
5. Taxodium.—The Mascall specimens are referred by
Knowlton to the widely distributed T. distichum mio-
cenum Heer, which should be called Taxodium distichum
dubium = Taxodium dubium (Sternb.) Heer, originally
described from Bilin. This differs from Sequoia by the
deciduous leaves, which are not decurrent at the base as
in Glyptostrobus. The genus still lives in our southern
states.
6. Artocarpus.—Represented by very fragmentary
material, doubtfully referred to A. californica Kn.
7. Magnolia.—Major Bendire collected a plant which
Knowlton says ‘‘may well be’’ M. inglefieldi Heer. It
has not been obtained by recent collectors. Magnolia
dayana Ckll. ined. (M. lanceolata Lx. 1878, not Link.
1831) is listed by Knowlton as from the Mascall, but in
his detailed account he says it is from Cherry Creek,
which should be Lower Eocene.
8. Laurus.— Florissant has a species of Persea; Laurus
and Persea are allied, and not distinctly separated by
paleobotanists.
9. Platanus.—The Maent specimens appear to belong
36 THE AMERICAN NATURALIST [Vou. XLIV
Fig. 3. Sequoia haydeni (Lesquereux). Redwood.
to three species, but none are sufficiently well preserved ;
for positive specifie identification.
10. Prunus.—The two Maseall species described by
Knowlton are only doubtfully referred to this genus,
which is of course abundant in the modern flora.
11. Rulac.—Generie reference rather uncertain; the
genus is scarcely separable from Acer, which occurs at
Florissant.
12. Æsculus.— This well-known living genus is repre-
a es I hy i ose Oy,
No. 517] MIOCENE TREES 37
sented in the Maseall by leaflets which closely resemble
an undescribed Florissant species which may be a Ber-
beris, but is certainly not an Æsculus.
15. Grewia.—The Maseall plant is referred by Knowl-
ton to G. crenata (Unger) Heer, which occurs in Europe
at Œningen.*
Three other genera, Phragmites, Cyperacites and
Smilax, are non-arborescent, and have no particular sig-
nificance.
Thus it would appear that in the Middle Miocene
period Ginkgo and Glyptostrobus—if we may accept the
determinations—had not yet retreated from the Amer-
ican continent, but survived at least in the northwest.
For the rest, the Maseall flora is no doubt a lowland one
as compared with that of Florissant, and this alone would
explain many of the differences; thus, no one would ex-
pect to find Taxodium growing around a mountain lake.
Dr. Knowlton has described (Monog. U. S. Geol. Sur-
vey, Vol. 32, part 2) an extensive flora from the Yellow-
stone, which he regards as Miocene. The fossil plants
of the Yellowstone National Park are divided by him into
three series: (1) Fort Union, which is Basal Eocene,
(2) Intermediate, said to be Miocene, and (3) Lamar
Flora, also Miocene. With the first we are not now con-
cerned, but the others must be compared with the flora
of Florissant. Considering the relative proximity of the
Yellowstone beds to those of Colorado, one would expect
to find much similarity and even identity in the plants;
but this is not the case. The difference of locality, with
a moderate difference in time, might perhaps account for
the diversity of species;-but the Yellowstone flora as a
whole does not impress one as being-so modern as that
of the Maseall beds or Florissant, while there is a sig-
nificant identity of species with those of the Eocene.
I have extracted from Knowlton’s tables a list of all
the Yellowstone ‘‘Miocene’’ plants said to occur else-
where or in the Eocene, with the following result:
*The African Grewia crenata Hochst., 1868 (not Unger, 1850), takes the
name G. populifolia Vahl, 1790.
38 THE AMERICAN NATURALIST [ Vou. XLIV
Fie. 4. Rhus “Bortarioides ATES Sumach.
1. Common to Fort ioe hn eee Intermediate
and Lamar.
Sequoia langsdorfii (Bregt.). Said to-go d cane to
the Laramie (Cretaceous).
Juglans rugosa Lx. Goes down to the came
Castanea pulchella Kn.
Ficus densifolia Kn.
Laurus californica Lx. Also auriferous gravels
of California.
Laurus grandis Lx. (not Wallich). Also aurif-
erous gravels of California.
Platanus guillelme Göpp. Perhaps also Laramie.
Aralia notata Lx. Also Denver beds.
* Eleodendron polymorphum Ward.
2. Common to Fort Union and Intermediate.
Equisetum canaliculatum Kn. Perhaps also in the
Lamar.
No. 517] MIOCENE TREES 39
Magnolia (2) pollardi Kn.
* Ulmus minima Ward?
Sapindus affinis Newby.
3. Common to Fort Union and Lamar.
Asplenium iddingsi Kn.
Lygodium kaulfussi Heer.
Equisetum deciduum Kn.
Juglans crescentia Kn.
Ficus asiminefolia Lx. Also auriferous gravels
of California.
Laurus primigenia Unger?
Malapænna lamarensis Kn.
Sapindus grandifoliolus Ward:
Sapindus wardii Kn.
* Hicoria antiqua (Newb.).
*Ulmus pseudofulva Lx.?
Those marked with an asterisk occur in the Fort Union
only outside of the Yellowstone.
4. Common to the Intermediate and the Denver beds
(Basal Eocene).
Osmunda affinis Lx.
5. Common to the Lamar, Basal Eocene and Laramie.
Rhamnus rectinervis Heer, Lx. Heer describes
this from Monod, in the Lower Miocene; we may
venture to doubt the identity of the American
plant.
Thus we have twenty-six plants specifically identical
with those of the Basal Eocene.”
6. Common to Lamar and ‘‘Green River” of Knowlton.
(See also under 7.)
Salix etongata O. Web. Said to occur at Elko
Station, Nevada, but-representèd only by un-
characteristic fragments. The determination of
5 The Maseall is supposed to have five species common to the Fort Union;
but of these two are doubtful, two others are the conifers Sequoia langs-
dorfii and Taxodium, while the fifth is Sapindus obtusifolius, to which a
sangle specimen from the Maseall ‘‘seems to belong.’’ S. obtusifolius was
originally described from beds supposed to belong to the Washakie (Later
Eocene). ;
THE AMERICAN NATURALIST [Vor. XLIV
-
Fic. 5. Ulmus hillie Lesquereux. Elm.
the Lamar plant is considered doubtful by
Knowlton.
Fagus (Fagopsis) longifolia (Lx.). Elko Station,
Nevada; Florissant (very abundant) and
Kocene (?) of British Columbia. The British
Columbia locality is on the Similkameen River,
whence come various fossil insects. Dr. Daw-
son (quoted by Scudder) considered these de-
posits Miocene. The Yellowstone collection in-
eludes about forty specimens which Knowlton
No. 517]
MIOCENE TREES 41
refers here, all from Fossil Forest Ridge. This
is, undoubtedly, a distinctively Miocene plant,
and must be accepted as pertinent evidence.
The determination must be presumed to be
correct, though it may be pointed out that
various other leaves have almost exactly
the same venation and appearance. ‘This is
especially true of the species of Zelkova, to
which genus Engler (1894) actually referred
F. longifolia, though the discovery of the fruit
has since shown that it is not related thereto.
Ulmus plurinervia, as figured by Heer from
Alaska, is also almost exactly like F. longifolia;
it is considered doubtfully Eocene, but Knowl-
ton has recognized it in the Maseall (Miocene).
From the shape of the base, and other features,
it seems to me certain that the Alaskan plant is
not the original U. plurinervia, of which Unger
gives four figures in the Chloris Protogea. The
latter is decidedly more elm-like in appearance.
Corylus macquarrti (Forbes) Heer. This plant,
as recognized in America, is a Fort Union and
possibly Laramie species; recorded also from
the Eocene (?) of Alaska.
Diospyros brachysepala A. Br. As recognized in
this country, this is a Laramie and Fort Union
species; the record from Florissant I believe to
be erroneous.
None of the above belong to the genuine Green River
series; three are quite without significance as indicating
Miocene affinities, but the Fagus stands out as a solitary
Miocene representative.
7. Common to the Lamar and the Auriferous api
of California. (See also under 1 and 3.)
Juglans leonis Ckil. Two specimens in the Lamar.
Populus balsamoides Göpp. Also Miocene (?) of
Alaska. Known in the Yellowstone only from
a fragment, which certainly can not be positively
determined as balsamoides: in fact, it shows
42 THE AMERICAN NATURALIST [ Vou. XLIV
Fig. 6. Myrica drymeja (Lesquereux).
some differences, at least as compared with the
original European balsamoides, which ought to
be specific.
Salix varians Gopp. Eocene (?) of Alaska. The
Lamar plant is a fragment, and according to the
figure, the margin is quite unlike that of the
European varians.
Salix angusta A. B. Said to occur also in the
Basal Eocene and true Green River. The
Lamar material consists of doubtful fragments.
Quercus furcinervis americana Kn.
Ficus shastensis Lx.?
. Ficus sordida Lx. A mere fragment from the
Lamar.
Ficus asiminefolia Lx. Very indifferent material
from the Lamar. Also Fort Union.
Magnolia californica Lx.? The Lamar plant is
represented by a single specimen, ‘‘so much
No. 517] MIOCENE TREES 43
broken that its positive identification is not pos-
sible’? (Knowlton).
Persea pseudocarolinensis Lx. The Lamar speci-
men figured, ‘‘the best one found,’’ consists of
the upper half of a leaf; what there is of it ap-
pears to agree with the Californian species, al-
though it has more lateral viens.
Rhus miata Lx.?
Aralia whitneyi Lx. Also in the Intermediate.
None of the Yellowstone specimens are perfect,
but they appear to belong to this handsome
species. ie
Thus the species common to the Lamar and Auriferous
gravels, but not known from Basal Eocene, are few, and
in several cases of doubtful identity. As the reference
of the Lamar to the Miocene rests wholly on the resem-
blance of the flora to that of the Auriferous gravels, with
the exception of the indication afforded by Fagus longi-
folia, it must be considered at least somewhat dubious.
It is also to be remarked that eleven species of plants are
supposed to be common to the Yellowstone Fort Union
and the Auriferous gravels, although two of these, at
least, are doubtfully from the gravels, while in four or
five cases the Yellowstone material is fragmentary or
doubtful.
It is one thing, however, to recognize distinct elements
in common between the Auriferous gravels and the
Lamar, and another to prove the latter Miocene thereby.
The former may be conceded, the latter I think not.
Lesquereux enumerates thirteen species from the Au-
riferous gravels which are almost identical with living
species; he also cites seventeen which are evidently, but
not very closely, related to living ones. Of the thirteen,
four are enumerated from the Lamar; of the seventeen,
not one. Of the four common to the Lamar, three are
dubious, and only Juglans leonis (a species represented
to-day by the Asiatic J. regia) appears to be of satis-
factory standing.
44 = THE AMERICAN NATURALIST (Vou. XLIV
Fic. 7. Populus crassa (Lesquereux). Cottonwood;
probably aid of P. lesquereuxi.
Fic. 8. Populus lesquereuxi Ckll. Cottonwood.
Four species of the Auriferous gravels are said by
Lesquereux to be identical with Miocene plants, but are
all unsatisfactory, as follows: (1) Fagus antipofii; per-
haps goes to the Laramie, and the Californian specimen
was only half a leaf. (2) Populus zaddachi; supposed
to go down to the Basal Eocene. (3) Ficus tiliefolia;®
Fie. 9. Salix ramaleyi Ckll. Willow.
° Ficus emery (A. Br.) Heer, 1856, has priority over F. tiliefolia
Baker, Jn. Linn. Soc. 21: 443 (1885), from Madagascar. The latter may
become Ficus baard n. n.
No. 517] MIOCENE TREES 45
said to go down to the Laramie. (4) Aralia zaddachi;
of uncertain determination, one of the specimens was -
Platanus dissecta. None of these is found in the Lamar,
but F. antipofii is in the Yellowstone Fort Union.
Kight other species from the Auriferous gravels are
stated to be allied to Miocene species, five of these being
also related to living plants. One of the five, Juglans
oregoniana, has since proved to be from the Mascall, and
not to occur in the Auriferous gravels. The other three
areas follows: |
Ficus sordida Lx. Allied to, or perhaps identical
with, F. grenlandica of Greenland. A frag-
ment referred to this has been found in the
Lamar.
Ficus mense n. n. (F. microphylla Lx., 1878, not
Salzm., Mart. Fl. Braz. 4: 983). Alhed to F.
planicostata—but this is a species of the Basal
Eocene and Laramie.
Aralia whitneyi Lx., said to be allied to an Evans-
ton species, which would be Eocene.
It is thus apparent that the Auriferous gravels flora
has no decisive Miocene affinities, but is composed of two
sets of plants, one related to living forms, the other to
those of the Eocene. It is known to be a mixed lot, and
when I recently suggested to Dr. J. C. Merriam, of the
University of California, that it might perhaps be partly
Pliocene and partly Eocene, he replied that this might
indeed be the ease.
It is further to be remarked that Knowlton formerly
regarded the Maseall flora as having affinity with that of
the Auriferous gravels; but he subsequently discovered
that certain of the species he had most relied on were
really confined to the Mascall, and did not occur in the
gravels at all. ‘This correlation therefore fails,’’ he
states, and the absence of relationship stands as an argu-
ment against the Miocene age of the gravels.
The conclusion seems to be legitimate that the Yellow-
stone Intermediate and Lamar flore are Upper Eocene,
or at least older than Miocene. Were they really Mio-
46 THE AMERICAN NATURALIST [ Vou. XLIV
Fie. 10. Ptelea modesta (Lesquereux). Fig. 11. Melia espulsa Ckll.
cene, with so much resemblance to even the Basal Eocene,
the Florissant flora, to get as far on the other side as its
lack of affinity would suggest, would have to be projected
somewhere into the future! If this opinion is in any
degree correct, Florissant remains as the only Rocky
Mountain locality for Miocene plants, so far as known.
The accompanying figures, all taken from specimens
obtained at Florissant by the University of Colorado ex-
peditions, will give a good idea of the material from that
locality. Nowhere else in America are Tertiary plants
so well preserved. As compared with the Eocene flora,
and especially the Basal Eocene, the Florissant trees
are more diverse in type, with usually smaller leaves,
which are often compound. Excessively moist condi-
tions are not indicated, though there was evidently much
more moisture than at the present day. Some of the
plants are even somewhat xerophytic, indicating that the
higher slopes may have been relatively dry. Osborn
remarks on the evidence of increasing summer droughts
No. 517] MIOCENE TREES 47
in the Middle Miocene. So far as the mammals are con-
cerned, this is chiefly indicated by the plains fauna. Ow-
ing to the generally higher temperature, the air was
probably moister than at present, but the moisture may
have carried farther, to be precipitated on the mountains.
Thus the conditions on the plains and towards the sea
may have resembled those of Southern and Lower Cali-
fornia to-day, with a comparatively damp atmosphere but
little or no preciptation during a considerable part of
the year. The desert fauna and flora of the southwest
is a highly specialized one, which has certainly not come
into existence since the Miocene, at least as regards its
fundamental types; so it becomes necessary to postulate
a desert region during Miocene times, and no doubt much
earlier. Whether we shall ever know much about the
Tertiary deserts from fossil remains is perhaps question-
able, though we certainly have evidence of a semi-desert
fauna, as is illustrated by the large tortoises of the Upper
Miocene. The Florissant beds afford us a wonderful
insight into the mountain life of the Miocene, and must
have a continually increasing significance in relation to
the evolution of the fauna and flora of this continent.
Most unfortunately, they have as yet yielded no recogniz-
able mammalian remains, but I am convinced that these
will eventually be found. The beds are far from being
exhausted, and comparatively little digging has been
done at the place where fragments of a mammal were
obtained—a locality which I shall be glad to describe in
detail to any one who cares to go and try his luck. In
the meanwhile, large collections both of plants and of in-
sects, already obtained, remain to be investigated and re-
ported upon, but for various reasons the work proceeds
slowly.
A SUGGESTION REGARDING HEAVY AND LIGHT
SEED GRAIN!
L. R. WALDRON
DICKINSON SUB-EXPERIMENT STATION, Dickinson, N. Dak.
A CONSIDERABLE amount of work has been done by in-
vestigators of cereals, regarding the comparative value
of heavy and light grains used as seed. The major por-
tion of the experiments have been conducted with wheat,
oats and barley. The problem appeared simple at the
beginning, but has developed many complications.
In many cases bulk grain has been graded into various
classes without determining the relative number of grains
per measured quantity. Thus the experiments have been
vitiated by the failure to consider the different rates of
seeding, as regards the number of grains per area, which
would naturally ensue. Even if allowance for seeding
were made, and the number of grains per area deter-
mined as accurately as possible, it would be an excel-
lent thing to conduct also a rate of sowing test. Such a
test might throw light upon results induced by climatic
conditions.
Some of the workers have made no distinction between
shriveled grains and small plump grains. To eliminate
the factor of shriveled grains would be virtually doing
away with fanning mill methods of grading, which would
seem to be necessary if we are to simplify the problem
and to obviate the conflicting factors. Zavitz, of Ontario,
has worked with small, hand-picked samples of grain and
has evidently succeeded in overcoming the difficulties
mentioned. His results, extending over a series of years,
are remarkably consistent and worthy of careful study.
Despite some of the errors one can not fail to be im-
pressed, as the literature is studied with the preponder-
* Contribution No. III, Laboratory Experimental Plant-breeding, Cornell
University.
48
arae = Me eee Benes
i vies f E TET TEN “oi Be ERS pina td Pen He
r sig Laas
PRS Rotate SRN TOO el eo EEE ee eM Co yD ES enw SAE NET PEE en Shen EER UA Meche ae are ee bean oe eA EL ta > PAY UMM Opry ee Ba N et Wee eas E AT
No. 517 | HEAVY AND LIGHT. SEED GRAIN 49
ance of evidence in favor of the large seed. The errors
are as apt to tell against the heavy seed as against the
light seed. In fact, where error has been most carefully
eliminated, as in the experiment of Zavitz, the large
seed gives the most striking positive results.
The result, empirically derived, while of great prac-
tical importance, does not throw much light on transmis-
sion. The majority of the experimenters have paid no
attention to the plants from which the large or small
grains have come. Bolley selected large and small grains
from the same heads of wheat and found that the large
grains generally produced the largest yields. Lyon has
stated that both large and small grains in a lot of wheat
must represent both large and small spikes, and if only
large grains are sown one is not necessarily selecting
from the best plants.
If, according to Johannsen,” “In a population contain-
ing only one single type, the selection of fluctuations has
no action at all,’’ then it would make no difference, as far
as transmission is concerned, if all sorts of plants were
represented in the seed, so long as we are dealing with a
pure line. Most American breeders, however, would
prefer to select for seed the best plants from the field
each year, even if working with a pure strain. This prac-
tice is doubtless based on opinion at the present time
rather than on well-grounded experimental knowledge.
We ought to be willing to acknowledge our ignorance of
the possibility of changing the type by selecting fluctua-
tions of close pollinated cereals. Until more and accurate
data can be secured a neutral position is much the better.
CORRELATION Data or Oats
The writer, in securing some statistical data on oats
preparatory to breeding, noticed that the data were in-
teresting in connection with the question of light and
heavy seed. Measurements were taken on 1,000 oat culms
grown at Dickinson, North Dakota, under field conditions.
In nearly all eases, each head-bearing culm measured rep-
* Rpt. Third Int. Conf. on Geneties, London, 1906.
THE AMERICAN
NATURALIST
[Vou. XLIV
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5 300 309 pa E ee are 2 1 46
6 310 319 2 {47°32 4% 1 1 21
7 320 329 ee Its 11
8 330 339 e ee 1 1 8
9 340 349 ; t 3
10 350.359 It 2 1 8
11 360 369 6
12 370 379 2 2
13 380 389 1 1
Pride 2 3 8 19 17 45 78 97137137 130142915425 9 4 11 1000
Fie. 2. _ correlation s oats. Aver weight of Spa subject, length of
eae relati Coefficient of prato = — 0.511 +. 0.0
Wis ssleite 6 Gi ia Gs ts Uo tee es a se
alee The lengths are expressed in centimeters. In Fig. 6 the weight
EREET oe T a aa
No. 517] HEAVY AND LIGHT SEED GRAIN 51
resented an entire plant. The variety is well defined
morphologically, but evidently contains various races or
biotypes.
Among other data secured was the height of cni, the
length of head, the number of grains per head and the
average weight of kernel. The various measurements
were correlated and the results prove very interesting.
Fig. 1 shows the correlation existing between the aver-
age weight of kernel as subject and the number of grains
per head as relative. A strong negative correlation is
noticed, amounting to very nearly 60 per cent. In other
words, the greater the number of grains per head, or, in
reality, the larger the head as regards grain, the less the
average weight per kernel.
The mean of the number of grains per head, of the pop-
ulation studied, is 22.098 and the mean weight per kernel
is 24.913 mg.
The regression coefficient of the number of grains rela-
tive to the average weight of grain is — 1.98. In other
words, if we should select grains for planting that weigh,
for instance, 30 mg. and above, they would on the whole be
selected from heads containing only about 12 or 13 grains,
which represent heads considerably below the mean.
There would doubtless be an occasional grain from heads
above the mean, but such grains would be uncommon and
the increasingly larger heads would be more and more
sparsely represented in the grain selected for planting.
Fig. 2 shows the correlation existing between the aver-
age weight of kernel as subject and the length of head as
relative. As the number of grains is quite dependent
upon the length of head we should expect to find a corre-
lation existing between the two, somewhat similar, as is
shown in Fig. 1. The actual correlation is negative and
amounts to 51 per cent. The mean length of the head is
13.583 cm.
The regression coefficient of the length of the head
relative to the average weight of grains is — 0.379. That
is, if we should select grains for planting that weigh, for
instance, 30 mg. and above, they would in general be
52 THE AMERICAN NATURALIST [Vou. XLIV
X, —36 —34 —32 —30 —28 —26 —24 —22 —20 —18 —16 —14 —12 —10 —8 6 —4 —2 0 2 4 6 8101214161820 3
27-99." g a e 87-80 41 & = 47 49 51 53 55 v æ 61 63 65 67 69 71 73 75 77 79 81 83 2a
28 80 82 34 36 88 40 42 44 48 50 52 54 56 60 62 64 66 68 70 72 74 76 78 80 82 84 m
— 10 150 159 1 1 | :
9 160 169 1
8470179 1 1 1 | 1 424 7
— 7 180 189 3 | 56 2 18
— 6190 199 Ri Gas Biel | ECOL 28
— 52002 1 Y 1 tp aIr DIAT 2 73
— 4210219 1 1 a E 8 eS E 9 166 N. 91
— 3 220 229 153 213 9 8| 91810 8 810 4 3 3 104
— 2230 239 ot Core: e te ea eo 8 ae 107
— 1240 249 bey eat Ay cures a die SL 13 | saie BS BT 104
0 250 259 2 1 (2523 e 8: | 0 2 BIO 8) r a 16: 8 eS 122
1 260 269 Seo a AN 7 18 6 6 OSE Ba 268 Sl 75
2 270 279 ees dices Comme Se he 06s 8 bec 4 18 146 I0. 28 2 1 1o
3 280 289 2 Pee Tn CAN EIEE aa be. 8b e a S Ea 1 55
4 290 299 2 1 eke DiS a ee 28 321 33
5 300 309 Poe ee ee OR ee be ee e E 1 46
6 310 319 i o2 See aR BS 1 1 21
7 320 1 1 1 ot Ae ed at 11
8 330 339 yg 2 1 1 8
340 1 1 1 | f
10 350 359 i i Pete 8 1 | ;
11 360 369 | 0
12 370 379 bed | :
380 |
|
aaeh e 0o e 2 9 Se Sio a oa] oi 76. 74 83-84 BS 08 91:68:99 29. 15 11 2
' Fie. 3. Correlation in oats. Average weight of grains subject, length of
culm relative. Coefficient of correlation, — 0.404 + 0.017.
X, —14 —12 —10 —8 —6 —4—2 0 2 4 6 81012 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 =
9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 sE
10 i it 16 18 30-22 40 42 44 46 48 50 52 54 56 58 60626466 1% 20
1
—11 £0 39 1 1
—10 90 99 3 3
1001 1 1 3
— $110 119 1 1 1 3
— 7120129 i | bes | 1 6
— 6 130 139 tT 4 tebe 2-6 2 4 1 13
— 5140 149 PaA: eae ane Ca 1 ijo
4150 159 si a SEG ore ee ee 17
— 3 160 169 $ i 1 530121 1 1 1 28
— 2170179 1 6 e PE 1 43°42 2 2 41
— 1180 189 oy 4 445 95 58 628 1 49
190 199 14. 2 hie 64 9 8 4 1 1 52
200 209 Lot's 8 YOR es 7 £2. tt 1 4
2 210 219 od eitas 24 24
3 22 229 1 1 + £5501 Bek Bs 1 2
4 230 239 to eee eg 1 1
5 240 249 1 1 ee ae | 1 €
250 259 2 i ari 1
260 269 1 1
8 270 279 ti í
289 iei
299 1
1
12 310 319 1
3 320
14 330 339 )
15 340 349
16 350 359
17 360
18 370 379
19 380
390 1
Weight :
: 18 F 0M OC OUMMANIS 91426 FOTO OR OT 354
Fie. 4. Correlation in winter wheat. verage weight of grains subject,
sera m number of ee per head relative. giir of correlation, o 1
No. 517] HEAVY AND LIGHT SEED GRAIN 53
selected from heads in the neighborhood of 11.5 em. long.
We should have to select the shorter heads in order to
secure the larger grains.
Fig. 3 shows the correlation existing between the aver-
age weight of kernel as subject, and the total height of
culm, including the head, as relative. The correlation is
still negative and amounts to 40 per cent. The mean
length of the culm is 61.74 em.
The regression coefficient of the length of the culm
relative to the average weight of grain is — 0.987. As in
the last example, the selection of grains weighing 30 mg.
and above would imply that they had come from culms
about 56 em. long, or about 5 em. below the mean.
As a summary, plants with shorter culms, shorter
heads, and with a smaller number of grains, bear on the
whole grains of a greater weight. The opposite of course
is equally true.
If the data had been taken of a pure strain of oats, of
the variety studied—of a number of plants that had come
within a few generations from a single mother plant—
then the correlations might have varied slightly from
those given. If data were accessible of another variety,
then we might suspect even greater deviation from the
figures given. Variation in the same variety from year
to year may be expected. However, there is nothing to
lead us to believe, from an a priori standpoint, that the
data given would be essentially changed.
If data were taken on oat plants grown in hills, then
we might get less decided negative correlations than those
given where the plants were grown under field conditions.
The variability of the number of grains, the height of
plant and the length of head might be less, while the vari-
ability of the average weight of grain might not be much
- different.
The following table shows the coefficients of variability
expressed in per cent. of the various factors that have
been discussed.
The factor of the number of grains is evidently the
much more variable one and perhaps under hill condi-
i a
= St
Ck Oo
54 THE AMERICAN NATURALIST [ Vout. XLIV
X, —34 —32 pko ia 28 = —24 —22 —20 —18 —16 —14 —12 padi —6—4-2 0 2 4 6 810 12 14 16 18 20 22 24 26
37 39 43 àT 49: 51 58 57 59 63 65 67 6971 737577 79 81 83 85 87 89 91 93 95 97
40 44 Š 48 52 54 56 58 60 6 64 66 68 7072 7476 78 80 82 84 86 88 90 92 94 96 98
Pah | |
—11 80 89 | 1
—10 90 99 bees 1
— 9100 109 1 2
— 8 110 119 1 r
— 7120 129 Ioi 1 1 1 1
— 6 130 139 1 1 1 se pall ee 1
— 5 140 149 2 1 1 14 1
— 4150 159 1 Eora t 1 2 4659-41 ey.
— 3 160 169 at Gaede: tube, oe, oe e ene fe aC as Te ee ea ig A ep a |
— 2170179 a see ee 3 ee ee et ae ee ae ee 1
— 1180 189 yD Pe E 2:3 44:3 bob 8-1-3
0 190 199 | 1 1 eat Skee EE Yrs 3°32 26 2°58 Pi 1 eee
1 200 beste” ae $ 3 4 Oe Ee 3 ee
2 210 219 1 1 vee ME ate ces rims Oe eee Oe Meee 1
3 220 229 1 LCR 2 2 $48 40524,1 4 4
4 230 239 1 3 1 UTES a YEP NS a A.
5 240 249 1 1 1 $71 1
6 250 259 2 1 Ware ae 1
7 260 269 1 1
8 270 279 1 1
9 280 289 fey
10 290 299 1
li 309 1
1
1
Y l T TEA 8 CTB 8 16. 8 8 28 82 2212. 2428 26-2218 10 17 11.14 § O71
‘average
Fic. 5. Correlation in winter wheat.
average length of culm relative.
Average weight of grains subject,
Coefticient of seen Hie 0.16 + 0. 034.
aHopkano enoehoauue
nF SESHESEE NERESNESs
X, 65 —
—2 4
14 15 $ p 18 ou A isete s Taa
84567 8
1
es
rz 1
3 |
251 | 1
saro y
2i oo]
4 13 3)
716 |
112,51 1
1/13 4
ee
6 2
ae
2 3
l 1
E ETTE e
Ji pad
ONADAN
mg.
1 5 10 14 95 31933 252011 8.2 1 01 187
Fro: 6. Correlation in winter ‘wheat.
volume
Average dak of grains subject,
of NE re lative. Coefficient of Don Fai; AE
354
No. 517] HEAVY AND LIGHT SEED GRAIN 55
tions it would be somewhat reduced, though this is only
problematical.
Factor. Coefficient of Variability.
Number of grains isson ei ae nk fk 54.5 + 2.33
Average weight of grains s.a.s. -picos 8.4%, 14.5 + 0.48
Length of head s.. S50. eet ee Sh 19.7 + 0.68
Length of enlm, s.is a e os vie oe 14.2 + 0.47
Since the above was written it has been found that the
small oat heads bear a somewhat larger percentage of
single grains than the large heads. If this factor be con-
sidered, the negative correlations would be somewhat de-
creased but probably not materially.
CORRELATION Data or WHEAT
In looking over the literature some unreduced winter
wheat data were found in Bulletin 78 of the Bureau of
Plant Industry by Dr. T. L. Lyon. A portion of this
data was thrown on to correlation tables and is given
herewith.
Fig. 4 shows the correlation existing between the aver-
age weight of kernel as subject and the average number
of grains per head as relative. Both the weight and num-
ber are averages for the entire plant. The figures are
thus not quite comparable to those given for the oat
plants, but are doubtless nearly so. Data for only 354
individual plants are given, but this number of plants
represents a considerably larger number of culms. The
correlation is negative and is a little over 11 per cent.
The regression of the average number of grains relative
to the average weight of grains is much diminished and a
selection of seed of either very high or of very low weight |
would not indicate that the seed was from plants located
any appreciable distance from the mean, as far as average
number of grains is concerned.
Fig. 5 shows the correlation existing in winter wheat
between the average weight of kernel as subject and the
average height of culm as relative. As in the previous
case, data for only 354 individuals are given. Instead of
a negative correlation, as in all previous cases, we have
56 THE AMERICAN NATURALIST [Vou. XLIV
here a positive correlation, amounting to 16 per cent.
This is a weak correlation. The regression of the average
height of culms is very slight. Selection of any particu-
lar weight of seed would not imply that any particular
heights of plants were involved.
It is interesting to note that the correlations given of
winter wheat hold about the same relations to each other
as do the corresponding correlations of the oats.
RELATION OF SIZE TO VOLUME OF GRAIN
But little aceurate data on this point are available.
We should expect to find a close correlation. The data
given in Fig. 6 are taken from Bulletin No. 78 mentioned
previously. It is seen that there is an almost perfect
correlation existing between the average weight of kernel
and the average volume per kernel. The three outstand-
ing individuals suggest errors rather than extreme
variations.
SuMMARY
If oat populations in general show constants similar
to those given, then the experimenter selecting the large
grains is not selecting from what is commonly considered
the best plants, and vice versa. If the plants from large
grains produce a better yield, then they must do so by
virtue of the increased vigor of the embryo and the in-
creased amount of food supply. If we consider that the
size and yield of the mother plant have an influence upon
the size and yield of the daughter plants, then we must
consider that this influence is decidedly less than the in-
fluence exerted by the size of the seed. If the size and
yield of the mother plant have no effect upon the off-
spring, then we might expect the yields from different
weights of seed to be somewhat in proportion to the
weights of seed.
Despite all that has been written on the foregoing
points we have very little accurate knowledge pertaining
thereto, especially relative to the influence of selection
upon the close pollinated cereals.
NOTES AND LITERATURE
MAMMALOGY
Nelson’s Monograph of the North American Leporidæ.— Mam-
malogists owe a debt of gratitude to Mr. E. W. Nelson for his
recent monographie revision of the hares and rabbits of North
America,’ the first revision of the group as a whole since the
publication of Allen’s monograph of this group in 1877. Mr.
Nelson, in addition to abundant material, has brought to his
task an intimate knowledge of these animals in life, and of the
environments to which the different groups of species are sub-
jected, through his many years’ experience as an explorer and
collector, covering a wide area, embracing Arctic Alaska, the
arid southwestern United States, Lower California, and the
whole of Mexico, including the tropical coast lands as well as
the plateau region. The monograph is based on the careful
study of nearly 6,000 specimens, all of the material contained
in the principal museums of America having been examined.
The number of species and subspecies recognized is 97, of which
93 are contained in the collections of the United States National
Museum. This is an increase of nearly 80 over the number
known in 1877.
The introduction (pp. 9-61) deals with the economic rela-
tions of the American rabbits to agriculture; the use of the
names rabbit and hare; the condition of the young at birth; the
distribution of the genera and species; their habits and diseases;
their color patterns, molts and seasonal changes of color; sexual,
individual and geographic variation; their classification, and
keys to the species and subspecies.
Points of general interest are the destructiveness of these
animals to vegetation, through injury to young trees, both in
orchards and newly planted forests; and their food value,
which, as is well known, is considerable, millions of rabbits being
sold in our markets each winter.
The names hare and rabbit were originally used in a specific
14: The Rabbits of North America,’’ by E. W. Nelson, chief field nat-
uralist, Biological Survey. Prepared under the direction of Dr. C. Hart
Merriam, Chief of Bureau of Biological Survey. North American Fauna,
No. 29, August 31, 1909. 8vo, pp. 1-314, pl. i-xiii, and 19 text figures.
57
58 THE AMERICAN NATURALIST [Vou. XLIV
sense to designate the two long-known European species; later
their use became greatly broadened and their application more
or less interchangeable, with different restrictions by different
authorities and in different countries. Mr. Nelson would con-
fine the use of the term hare, so far as American species are con-
cerned, to the restricted genus Lepus (including the varying
and Arctic hares and the jack rabbits), and employ the term
rabbit for the ‘‘cotton-tails’’ or smaller brush rabbits and
swamp rabbits (genus Sylvilagus and allied forms). The hares
are, generally speaking, larger than the rabbits, live mostly in
‘forms,’ and bring forth young with open eyes and well-
clothed with hair; many of the rabbits are known to bring forth
their young naked and blind; while some of them burrow, others
live in forms, like the true hares.
Formerly all the species of Leporidæ were referred to the
single genus Lepus, but later, mainly within the last decade,
several genera have been recognized by the leading authorities
on the group, together with a number of subgenera. Mr. Nelson
arranges the North American species in four genera-—Lepus,
Sylvilagus, Brachylagus and Romerolagus. The last two are
monotypic with very restricted ranges; the rest of the species
are assigned to Lepus (with two subgenera, Lepus = Arctic and
varying hares, and Macrotolagus == ‘‘jack rabbits’’) and Sylvi-
lagus (also with two subgenera, Sylvilagus = ‘‘cotton-tails”’
brush rabbits) and Tapeti (swamp rabbits. The latter includes
most of the species of Central and South America).
The hares of the subgenus Lepus (the Arctic and varying
hares) have a double molt, being brown in summer and white in
winter, while the other species are believed to molt, for the most
part at least, only once (in fall), and the only seasonal change
of color is due to the fading and abrasion of the long-worn coat.
Formerly it was supposed that the white winter coat of all the
northern hares was due to a change of color in the hair itself of
the summer coat. On this point Mr. Nelson says:
The change in color from the white winter pelage of northern species
to the dark summer coat, or vice versa, is accomplished so gradually
that at certain stages it appears like a change in the color of the hairs
instead of a molt, as was definitely proved by sore Allen in his
paper on the changes of pelage of the varying hare
This supposed change of color in the ‘abies: he further says,
? Bull. Am. Mus. Nat. Hist., VI, pp. 107-128, May 7, 1894.
No. 517] NOTES AND LITERATURE 59
“‘may be readily disproved by a careful examination of a few
molting specimens.’’ It is also now well known that the white
winter coat of the ermines and weasels, and of such species of
lemmings as turn white in winter, is due to molt and not to a
blanching of the hairs of the summer coat. In other words,
seasonal change of color in mammals, as well as in birds, is due
entirely to molt. In the case of the hares and weasels, the
change to white in winter is only partial at the southern border
of the ranges of species that further north become wholly white
in winter, while the most northern forms of the Arctic hare
group remain practically white in summer, as in northern
Greenland and northern Ellesmere Land. The time of molt
also varies with the character of the season. As has long been
known, an early spring or fall brings on the molt a month or
more earlier than a later one, and hence a change of color in
such species as have a white winter livery is correspondingly
ater.
Mr. Nelson confirms the statements of previous writers that
the pelage in mammals is in other ways subject to modification
by the environment, as through variation in its length and den-
sity in accordance with the severity of the climate. In discuss-
ing the effect of environment, he also confirms the experience
of other mammalogists, and of ornithologists and herpetologists
as well, that ‘‘like climatic conditions often produce the same
or closely similar colors in dissimilar species,’’ and also parallel
modifications in other features, including cranial details of
structure.
These fluctuations are somewhat wavelike in character and rise to
central points of extreme development and then sink away to inter-
mediate borders beyond which new waves arise. When the waves of
differentiation are pronounced they mark recognizable geographic races.
. In the ease of wide-ranging subspecies such fluctuations are fre-
pies: especially where the areas occupied are diversified by mountains.
These fluctuations, which are sometimes extremely local, mark, of course,
potential subspecies. Some are fairly well characterized and eventually
may be named, while others are too slight to be formally recognized by
name, but well serve to illustrate the plastie condition of the species.
The transition from one subspecies to another takes place abruptly or
gradually in exact accord with the changes of environment which pro-
duce them... . 3
As is well known, many mammals are subject to periodie de-
struction by disease. This is especially marked among rodents,
60 THE AMERICAN NATURALIST — [Vou XLIV
such as voles, ground-squirrels and rabbits, and their reduction
or increase in numbers, as the case may be, powerfully affects
the welfare of such species of mammals and birds as prey upon
them. In the ease of rabbits, destruction by epidemics is peri-
odical, occurring apparently about once in seven years, although
exact data are wanting as to the regularity or frequency of these
epidemics, or their exact nature. They are at times so severe
that only a few individuals are left to perpetuate the species.
They are also followed, there is some reason to believe, by an
inereased birthrate by which the stock is rapidly replenished.
This periodie destruction is considered by Mr. Nelson in relation
to the apparent opportunity thus afforded for the origination,
through isolation, of many strongly characterized forms, but he
fails to find evidence that this is an evolutionary force of much
importance. The Lepus americanus group, occupying the vast
wooded area from Nova Scotia to western Alaska, which has been
subjected to numberless recurring periods of extreme abundance
and extreme scarcity, presents only a few, and not strongly,
differentiated subspecies, owing, it is believed, to the leveling
influence of similarity of climate.
In illustration, however, of the effects of complete isolation
under similar climatic conditions, the black jack rabbit of the
island of Espiritu Santo is cited.. This small island lies off La
Paz Bay, Lower California, only four miles from the mainland,
from which it is separated by a channel having in its shallower
parts only four to five fathoms of water. The island was doubt-
less formerly a part of the mainland, and has still the same
character of vegetation and climate. The adjacent mainland is
occupied by a pale form of the Lepus californicus group, the is-
land by a form essentially the same in size and cranial char-
acters, but so dark in color as to be commonly referred to as the
‘‘black’’? jack rabbit. The intensification of color, making it
‘‘extraordinarily conspicuous,’’ has not been ‘‘protective,’’ nor
yet has it proved a detriment, presumably from the fact that no
predatory mammal or large bird of prey shares its habitat.
Coming now to the systematie portion of the monograph, it
may be noted that the genera and subgenera here recognized are
very satisfactorily characterized, and the keys to the species and
subspecies are carefully elaborated, oceupying ten pages for the
97 forms recognized. These, in the systematic part of the mono-
graph, are treated very fully in respect to their distinetive char-
No. 517] NOTES AND LITERATURE 61
acters, ranges and relationships. There is, however, very little
on the historical side of the subject beyond a briefly annotated
bibliography of sixty-six titles (pp. 282-287), prefaced by a
page and a half of historical résumé. The citations under the
species relate almost wholly to synonyms, which in this group of
American mammals are fortunately exceptionally few. There
is little to indicate the point of view of previous writers, or their
manner of treatment as regards forms recognized and their
allocation. The correlation, from the author’s standpoint, of
work previously done is an essential feature of a monographie
treatise; and this can be fairly shown in tables of reference,’
with such slight additional comment as may seem necessary.
This defect in the present case is doubtless a feature of environ-
ment, due to limitations already referred to in another connec-
tion.* Yet it seems strange to find no reference under the genus
Romerolagus to the discussion of the structure and affinities of
this interesting type by previous authors, as Lyon, Major and
Herrara, nor to the alleged earlier competitive name for the
species, namely Lepus diazi Ferrari Perez (1893).
As already intimated, the systematice treatment is in general
excellent. . The species is first considered as a whole; its sub-
specific components are passed in review, their ranges shown
graphically on a map, and a table gives the average measure-
ments, external and eranial, of five specimens of each form, the
same external measurements being repeated later in their
proper connection in the text. This number, however, is too
few to be satisfactory, and extremes of variation are not indi-
cated. Under the subspecies the geographic range is first indi-
eated, followed by a paragraph of ‘‘general characters,’’ and
very full descriptions of the coloration, seasonal variations,
cranial distinctions, and such ‘‘remarks’’ as circumstances may
require. In view of the material studied by the author, and his
standing as an investigator, criticism of details would be out of
place unless based on equal opportunities. Mr. Nelson, how-
ever, has given a decidedly new aspect to the nomenclature of
the group, through the revival of certain previously unidentified
names, the merging of the terianus group of former authors
with the californicus group, of the arizone group with the audu-
* Note, for example, the synonymies in Ridgway’s ‘‘ Birds of North and
Middle America.’’
t AMERICAN NATURALIST, Vol. XLIII, October, 1909, p. 639.
62 THE AMERICAN NATURALIST [ Vou. XLIV
boni group, the reduction to subspecies of numerous forms pre-
viously recognized as species, and the raising to specific rank of
forms formerly treated as subspecies.
The only new form appears to be a subspecies littoralis of
Lepus aquaticus Bachman, through the assignment of a type
locality for aquaticus. As Mr. Nelson says, there ‘‘was no defi-
nite type,’’ and the species was described ‘‘from specimens ob-
tained in western Alabama by Dr. J. M. Lee. .. . No definite
type locality is mentioned, but the context appears to indicate
that these specimens came from western Alabama, which may be
considered the type region.” He further states that ‘‘the types
do not appear to have been preserved,’’ and were thus unavail-
able as an aid in settling the type locality. In the original ac-
count of this species Dr. Bachman said that he did not know of
its existence ‘‘to the east or north of the State of Alabama,”’
but that ‘‘it is numerous in all the swamps of the western parts
of that state, is still more abundant in the State of Mississippi
and the lower parts® of Louisiana, and is frequently brought by
the Indians to the market of New Orleans.’’ If Mr. Nelson had
been the first to split the Lepus aquaticus group into a Gulf
coast form and an interior form his course would be justifiable,
but this division was made long before, when the Lepus aquati-
cus attwateri was separated on the basis of comparison of speci-
mens from the vicinity of San Antonio, Texas, with a series from
the vicinity of New Orleans. He recognizes only the same two
forms, so that his littoralis is properly a synonym of Lepus
aquaticus aquaticus, with the name of the interior form still
Lepus aquaticus attwateri. Were it conclusively known that
the type locality of aquaticus was within the range of the inte-
rior form, he would be fully justified in his present ruling, but in
view of the fact that it is at best conjectural, and that the same
division of the species he now makes had been made before, thus
in effect restricting the name aquaticus to the Gulf coast form,
his action in the case seems at least open to reasonable objection.
The illustrations comprise twelve excellent plates (from photo-
graphs) of skulls of the different leading types of North Amer-
ican hares and rabbits, a plate (from a wash drawing) of
“directive coloration in Lepus callotis,” and nineteen text fig-
ures, sixteen of which are distribution maps, and three illus-
trate osteological characters in the genera Lepus and Sylvilagus.
Not italicized in the original.
No. 517] NOTES AND LITERATURE 63
The ‘‘directive coloration’’ plate shows two specimens of a Mex-
ican species of jack rabbit, which has white sides and a dark
buffy mantle covering the back. One figure shows the mantle
in its usual position, the other with the mantle ‘‘shifted to the
opposite side and the whitish area of the side drawn up nearly
or quite to the dorsal line,’’ the animal being then in the act
of ‘‘signalling.’’ This extraordinary feat is described at length
on page 115, where it is said that ‘‘By means of muscles the
skin of either side can be drawn over the back at will.” Mr.
Nelson further states that on one occasion one of these rabbits
observed by him kept the ‘‘white area in the same position until
it had traveled 50 or 60 yards, when the colors slowly resumed
their normal positions.’’
Despite the slight criticisms we have felt called upon to make,
Mr. Nelson’s ‘‘The Rabbits of North America’’ marks an era in
the history of the group, and is so comprehensive and so well
done that it must long remain the basis for future work, to be.
corrected doubtless in many minor details as new material is re-
ceived, but nevertheless a boon to all workers in North American
mammalogy.
J. A. ALLEN.
AMERICAN MUSEUM OF NATURAL HISTORY.
NEUROLOGY
Edinger’s ‘‘Vorlesungen über den Bau der nervösen Central-
organe” made its first appearance as a small volume in 1885.
Its directness and lucidity gained for it at once a deserved pop-
ularity and a growing demand justified the numerous editions
under which it subsequently appeared. In its latest form, the
seventh edition, the work consists of two volumes, either of which
is about twice the size of the original edition. This considerable
expansion has taken the work away from the circle of readers,
mostly medical students and physicians, for whom the earlier
editions were intended. It is therefore natural that an effort
should be made to return to the earlier form and this effort has
found its realization in the present ‘‘Introduction.’’* This vol-
ume, which contains a little less than two hundred pages, is a
1 Edinger, L., ‘‘ Einführung in die Lehre vom Bau und den Verrichtungen
des Nervenssystems.’’ Leipzig, F. C. W. Vogel, 190 pp., 161 figures, 1
plate, 1909.
64 THE AMERICAN NATURALIST (Vor. XLIV
summary of the larger work, but with the emphasis laid on the
human central nervous organs. The presentation has the great
advantage of beginning with the consideration of the spinal cord,
the more primitive part of the central nervous system, and then
proceeding to the more specialized part, the brain, instead of
dealing with these subjects in the reverse order as in the early
editions of the ‘‘Lectures.’’ The condensation has been most
admirably done, and, as a work that is intended to state briefly
those matters that are best established for the structure of the
central nervous organs in man, it is a masterpiece. The regrets
that one may have about the volume are chiefly because of
omissions, but condensation implies omissions and it is hard to
imagine under the circumstances a better selection of materials.
In one respect the general presentation might perhaps have been
improved. It is strange that Dr. Edinger, who accepts the
neurone theory so completely, should have abandoned this
method of presentation in dealing with the brain, though he
adopts it in his account of the cord. Possibly, however, the
greater uncertainty of resolving the brain from the standpoint
of the neurone as compared with the cord, is a justification for
this difference of treatment. In illustration and typography the
volume is on as high a level as in subject matter.
G. H. PARKER.
>
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THE
AMERICAN NATURALIST
No. 518
VoL. XLIV February, 1910
A MENDELIAN INTERPRETATION OF VARIA-
TION THAT IS APPARENTLY
CONTINUOUS!
PROFESSOR EDWARD M. EAST
HARVARD UNIVERSITY
THERE are two objects in writing this paper. One is to
present some new facts of inheritance obtained from pedi-
gree cultures of maize; the other is to discuss the hy-
potheses to which an extension of this class of facts
naturally leads. This discussion is to be regarded simply
as a suggestion toward a working hypothesis, for the facts
are not sufficient to support a theory. They do, however,
impose certain limitations upon speculation which should
receive careful consideration.
The facts which are submitted have to do with inde-
_ pendent allelomorphie pairs which cause the formation of
like or similar characters in the zygote. Nilsson-Ehle?
has just published facts of the same character obtained
from cultures of oats and of wheat. My own work is
largely supplementary to his, but it had been given these
interpretations previous to the publication of his paper. ©
In brief, Nilsson-Ehle’s results are as follows: He
found that while in most varieties of oats with black
1 Contributions from the Laboratory of Genetics, Bussey Institution, Har-
vard University, No. 4. Read before the annual meeting of the American
Society of Naturalists, Boston, December 29, 1909.
2 Nilsson-Ehle, H. Kreuzungsuntersuchungen an Hafer und Weizen.
Lunds Universitets Arsskrift, N. F. Afd. 2., Bd. 5, No. 2, 1909.
65
66 THE AMERICAN NATURALIST [Vou. XLIV
glumes blackness behaved as a simple Mendelian mono-
hybrid, yet in one case there were two definite inde-
pendent Mendelian unit characters, each of which was
allelomorphic to its absence. Furthermore, in most varie-
ties of oats having a ligule, the character behaved as a
mono-hybrid dominant to absence of ligule, but in one case
no less than four independent characters for presence of
ligule, each being dominant to its absence, were found. In
wheat a similar phenomenon occurred. Many crosses
were made between varieties having red seeds and those
having white seeds. In every case but one the F, gen-
eration gave the ordinary ratio of three red to one white.
In the one exception—a very old red variety from the
north of Sweden—the ratio in the F, generation was 63
red to 1 white. The reds of the F, generation gave in
the F, generation a very close approximation to the theo-
retical expectation, which is 37 constant red, 8 red and
white separating in the ratio of 63:1, 12 red and white
separating in the ratio of 15:1, 6 red and white separating
in the ratio of 3:1, and one constant white. He did not
happen to obtain the expected constant white, but in the
total progeny of 78 F, plants his other results are so close
to the theoretical calculation that they quite convince one
that he was really dealing with three indistinguishable but
independent red characters, each allelomorphie to its
absence. Nor can the experimental proof of the two
colors of the oat glumes be doubted. The evidence of
four characters for presence of ligule in the oat is not so
conclusive.
In my own work there is sufficient proof to show that in
certain cases the endosperm of maize contains two indis-
tinguishable, independent vellow colors, although in most
yellow races only one color is present. There is also some
evidence that there are three and possibly four inde-
pendent red colors in the pericarp, and two colors in the
aleurone cells. The colors in the aleurone cells when pure
are easily distinguished, but when they are together they
-~ grade into each other very gradually. 3
No. 518] VARIATION 67
Fully fifteen different yellow varieties of maize have
been crossed with various white varieties, in which the
crosses have all given a simple mono-hybrid ratio. In the
other cases that follow it is seen that there is a di-hybrid
ratio. l
No. 5-20, a pure white eight-rowed flint, was pollinated
by No. 6, a dent pure for yellow endosperm. An eight-
rowed ear was obtained containing 159 medium yellow
kernels and 145 light yellow kernels. The pollen parent
was evidently a hybrid homozygous for one yellow which
we will call Y, and heterozygous for another yellow Y,.
The gametes Y,Y, and Y, fertilized the white in equal
quantities, giving a ratio of approximately one medium
yellow to one light yellow. The F, kernels from the dark
yellow were as follows:
TABLE - 1.3
F, Serps rrom Cross or No. 5-20, WHITE FLINT X No. 6 YELLOW DENT,
HOMOZYGOUS FOR Y, AND HETEROZYGOUS FoR Y,
Dark Seeds Heterozygous for Both Yellows Planted
Ear No, Dark F. Light F. Totaly. | No¥.
1 270 56 326 29
2 101 215 316 27
3 1 52 313 28
5 273 284 557
10 358 117 475
12 296 72 368 19
13 7 156
14 387 102 489 29
Total 2153 1054 3207 227
Ratio | : wio oo tea
The ratios of light yellows to dark yellows is very arbi-
trary, for there was a fine gradation of shades. The ratio
of total yellows to white, however, is unmistakably 15: 1.
In the next table (Table II) are given the results of F,
kernels from the light yellows of F,. Only ear No. 8,
which was really planted with the dark yellows, showed
yellows dark enough to be mistaken for kernels containing
? In these tables only hand pollinated ears are given.
68 THE AMERICAN NATURALIST [Vou. XLIV
both Y, and Y.. The remaining ears are clearly mono-
hybrids with reference to yellow endosperm.
Tapte H:
F, SEEDS FROM SAME CROSS AS SHOWN IN TABLE I
Light Yellow Seeds ZETT ia ARY Planted
Ear No. eo : Dark Y. L Light Y. Y.
| We ®
1 | 359 | 117
2 | : 144 | 54
3 | 173 63
4 433 136
6 | 316 120
8 331 | 109
8a | | 229
9 325 115
10 | 227 7
11t | 4 434
12 318 118
13 256 93
Total | 3111 1098
Ratio | ed 2.8 1
In a second case the female parent possessed the yellow
endosperm. No. 11, a twelve-rowed yellow flint, was
crossed with No. 8, a white dent. The F, kernels in part
showed clearly a mono-hybrid ratio, and in part blended
gradually into white. Two of these indefinite ears proved
in the F, generation to have had the 15:1 ratio in the F,
generation. Ear 7 of the F, generation calculated from
the results of the entire F, crop must have had about 547
yellow to 52 white kernels, the theoretical number being
561 to 31. The hand-pollinated ears of the F, generation
(yellow seeds) gave the results shown in Table III.
e F, generation grown from the other ear, Ear No. 8,
showed that the ratio of yellows to whites in the F, gen-
eration was about 227 to 47. As the theoretical ratio is
257 to 17, the ratio obtained is somewhat inconclusive. A
classification of the open field crop could not be made
accurately on account of the light color of the yellows and
*Discarded from average. This ear evidently grew from one kernel of
the original white mother that was accidentally self-pollinated. The four
yellow kernels all show zenia from accidental pollination in the next
generat ion.
No. 518] VARIATION 69
Taste III.
No. 11 YELLow X No. 8 WHITE
F, Generation from Yellow Seeds of F, Generation
EarX No. o | D Dark) Y. Eh Light R _ Total Y No oY. _ Ratio They Approximate,
1 95 aay 19 15Y:lnoY
14 88 | 5 15Y:1noY
0 | 122 3YıY: 1 Yiors
4 = 253 re 8Y:1n
6 193 | 73 ýs
8 163 | 79 as
11 | 108 | 35 =
9 456 | Constant Yj or»
the presence of many kernels showing zenia. Table IV,
however, showing the hand-pollinated kernels of the inter-
bred yellows of the F, generation, settles beyond a doubt
the fact that the two yellows were present.
Taste IV.
PROGENY OF EAR No. 8 OF THE SAME CROSS AS SHOWN IN TABLE III
F, Generation from Yellow Seeds of F, Generation
Ear No. | Dark Y. | Light Y. | Total Y. | Noy. | Ratio They Approximate.
| |
10 101 188 | 289 % |- BY:lmy
11 89 219 308 | 5Y :1noY
233 | constant light b'g
9 dak adlie d D] 3 dark : 1 light Y
13 dark and light | 350 . 3 dark : 1 light Y
8 294 108 3 light : 1 no Y
15 221 | 87 3 light : 1 no Y
B| 197. | | 203
In a third case an eight-rowed yellow flint, No. 22, was
crossed with a white dent, No. 8. Only four selfed ears
were obtained in the F, generation. Ear 1 had 72 yellow
to 37 white kernels. This ear was poorly developed and
undoubtedly had some yellow kernels which were classed
as whites. Ear 4 had 158 yellow and 42 white kernels.
It is very likely that both of these ears were mono-hybrids,
but the F, generation was not grown. Ear 5 had 148
yellow and 15 white kernels. Ear 7 had 78 yellow and 5
white kernels. It seems probable that both of these ears
ë Kernel from which this ear grew was evidently pollinated by no Y.
70 THE AMERICAN NATURALIST [VoL. XLIV
were di-hybrids, but only Ear 5 was grown another
generation. The kernels classed as white proved to be
pure; the open field crop from the yellow kernels gave 14
pure yellow ears and 14 hybrid yellow. Theoretically
the ratio should be 7 pure yellows (that is, pure for
either one or both yellows) and 8 hybrid yellows (4 giv-
ing 15 yellows to 1 white and 4 giving 3 yellows to 1
white). Five hand-pollinated selfed ears were obtained.
Three of these gave mono-hybrid ratios, with a total of
607 yellows to 185 white kernels. One ear was a pure
dark yellow (probably Y,Y,Y.Y.). The other ear was
poorly filled, but had 27 dark yellows (probably. Y,Y,)
and 7 light yellow kernels (Y, or Y,). Unfortunately no
15:1 ratio was obtained in this generation, but this is quite
likely to happen when only five selfed ears are counted.
The gradation of colors and the general appearance of
the open field crop, however, lead me to believe that we
were again dealing with a di-hybrid.
Two yellows appeared in still another case, that of white
sweet No. 402 X yellow dent No. 33. Only one selfed
ear was obtained in the F, generation giving 599 yellow
to 43 white kernels. Of these kernels 486 were starchy |
and 156 sweet, which complicated matters in the F, gen-
eration because it was very difficult to separate the light
yellow sweet from the white sweet kernels. Among the
selfed ears were three pure to the starchy character, and
in these ears the dark yellows, the light yellows and whites
stood out very distinctly. Ear 12 had 156 dark yellow;
47 light yellow; 14 white kernels. Ear 13 had 347 dark
yellow; 93 light yellow; 25 white kernels. The third
starchy ear, No. 6, had 320 light yellow; 97 white kernels.
Two ears, therefore, were di-hybrids, and one ear a mono-
hybrid.
The ears which were heterozygous for starch and no
starch and those homozygous for no starch, could not all
be classified accurately, but it is certain that some pure
dark yellows, some pure light yellows, some showing seg-
regation of yellows and whites at the ratio 15:1, and some
No. 518] VARIATION 71
showing segregation of yellows and whites at the ratio of
3:1, were obtained,
One other case should be mentioned. One ear of a dent
variety of unknown parentage obtained for another
purpose was found to have some apparently hetero-
zygous yellow kernels. Seven selfed ears were obtained
from them, of which two were pure yellow. The other
five ears each gave the di-hybrid ratio. There was a
total of 1906 yellow seeds to 181 white seeds, which is
reasonably close to the expected ratio, 1956 yellow to 131
white.
It is to be regretted that I can present no other case of
this class that has been fully worked out, although several
other characters which I have under observation in both
maize and tobacco seem likely to be included ultimately.
Nevertheless, the fact that we have to deal with conditions
of this kind in studying inheritance is established; grant-
ing only that they will be somewhat numerous, it opens up
an entirely new outlook in the field of genetics.
In certain cases it would appear that we may have
several allelomorphie pairs each of which is inherited in-
dependently of the others, and each of which is separately
capable of forming the same character. When present in
different numbers in different individuals, these units
simply form quantitative differences. It may be objected
that we do not know that two colors that appear the same
physically are exactly the same chemically. That is true;
but Nilsson-Ehle’s case of several unit characters for
presence of ligule in oats is certainly one where each of
several Mendelian units forms exactly the same char-
acter. It may be that there is a kind of biological
isomerism, in which, instead of molecules of the same
formula having different physical properties, there are
isomers capable of forming the same character, although,
through difference in construction, they are not allelo-
morphie to each other. At least it is quite a probable
supposition that through imperfections in the mechanism
of heredity an individual possessing a certain character
12 THE AMERICAN NATURALIST [Not XLIV
should give rise to different lines of descent so that in the
Fn generation when individuals of these different lines
are crossed, the character behaves as a di-hybrid instead
of as a mono-hybrid. In other words, it is more probable
that these units arise through variation in different in-
dividuals and are combined by hybridization, than that
actually different structures for forming the same char-
acter arise in the same individual.
On the other hand, there is a possibility of an action just
the opposite of this. Several of these quantitative units
which produce the same character may become attached
like a chemical radical and again behave as a single pair.
Nilsson-Ehle gives one case which he does not attempt to
explain, where the same cross gave a 4:1 ratio in one
instance and 8.4:1 ratio in another instance. In his other
work characters always behaved the same way; that is,
either as one pair, two pairs, three pairs, ete. In my
work, the yellow endosperm of maize has behaved dif-
ferently in the same strain, but it is probably because the
yellow parent is homozygous for one yellow and heter-
ozygous for the other. They were known to be pure for
one yellow, but it would take a long series of crosses to
prove purity in two yellows.
Let us now consider what is the concrete result of the
inter-action of several cumulative units affecting the same
character. Where there is simple presence dominant to
absence of a number n of such factors, in a cross where all
are present in one parent and all absent in the other
parent, there must be 4" individuals to run an even chance
of obtaining a single F, individual in which the character
is absent. When four such units, 4,4,4,A, are crossed
with a,a,a,a,, their absence, only one pure recessive is
expected in 256 individuals. And 256 individuals is a
larger number than is usually reported in genetic publica-
tions. When a smaller population is considered, it will
appear to be a blend of the two parents with a fluctuating ©
variability on each side of its mode. Of course if there
is absolute dominance and each unit appears to affect the
No. 518] VARIATION 73
zygote in the same manner that they do when combined,
the F, generation will appear like the dominant parent
unless a very large number of progeny are under observa-
tion and pure recessives are obtained. This may be an
explanation of the results obtained by Millardet; it is cer-
tainly as probable as the hypothesis of the non-formation
of homozygotes. Ordinarily, however, there is not per-
fect dominance, and variation due to heterozygosis com-
bined with fluctuating variation makes it almost impos-
sible to classify the individuals except by breeding. The
two yellows in the endosperm of maize is an example of
how few characters are necessary to make classification
difficult. First, there is a small amount of fluctuation in
different ears due to varying light conditions owing to
differences in thickness of the husk; second, all the classes
having different gametic formule differ in the intensity
of their yellow in the following order, Y,Y,Y.Y,,
Y iyı Y¥ Y, or Y, Y, Ysy, YY, YoY, Viti, YoYo, YY As
dominance becomes less and less evident, the Mendelian
classes vary more and more from the formula (3 +1)”,
and approach the normal curve, with a regular gradation
of individuals on each side of the mode. When there is
no dominance and open fertilization, a state is reached
in which the curve of variation simulates the fluctuation
curve, with the difference that the gradations are herit-
able.
One other important feature of this class of genetic
facts must be considered. If units 4,4 A,a, meet units
aaz, in the F, generation there will be one pure re-
cessive, @,0.4,d,, in every 256 individuals. This explains
an apparent paradox. Two individuals are crossed, both
seemingly pure for presence of the same character, yet
one individual out of 256 is a pure recessive. When we
consider the rarity with which pure dominants or pure -
recessives (for all characters) are obtained when there are
more than three factors, we can hardly avoid the suspicion
that here is a perfectly logical way of accounting for
many cases of so-called atavism. Furthermore, many ap-
74 THE AMERICAN NATURALIST [Vou. XLIV
parently new characters may be formed by the gradual
dropping of these cumulative factors without any addi-
tional hypothesis. For example, in Nicotiana tabacum
varieties there is every gradation® of loss of leaf surface
near the base of the sessile leaf, until in N. tabacum fruti-
cosa the leaf is only one step removed from a petioled
condition. If this step should occur the new plant would
almost certainly be called a new species; yet it is only one
degree further in a definite series of loss gradations that
have already taken place. If it should be assumed that
in other instances slight qualitative as well as quantita-
tive changes take place as units are added, then it becomes
very easy, theoretically, to account for quite different
characters in the individual homozygous for presence of
all dominant units, and in the individual in which they
are all absent.
Unfortunately for these conceptions, although I feel it
extremely probable that variations in some characters
that seem to be continuous will prove to be combinations
of segregating characters, it is exceedingly difficult to
demonstrate the matter beyond a reasonable doubt. As
an illustration of the difficulties involved in the analysis
of pedigree cultures embracing such characters, I wish
to discuss some data regarding the inheritance of the
number of rows of kernels on the maize cob.
The maize ear may be regarded as a fusion of four or
more spikes, each joint of the rachis bearing two spikelets.
The rows are, therefore, distinctly paired, and no case is
known where one of the pair has been aborted. This is a
peculiar fact when we consider the great number of odd
kinds of variations that occur in nature. The number of
rows per cob has been considered to belong to continuous
variations by DeVries, and a glance at the progeny from
- the seeds of a single selfed ear as shown in pone V seems
to confirm this view.
There is considerable evidence, however, that this char-
acter is made up of a series of cumulative units, inde-
_*It is not known at present how this character behaves in inheritance.
No. 518] VARIATION 75
TABLE V.
PROGENY OF A SELFED Ear or LEAMING MAIZE HAVING 20 Rows
Classes ai FOWSS ii 12 14 16 18 20 22 2 2 28
PLOs E a T a, LO Bi ABS. 36 10 5 3
pendent in their inheritance. There is no reason why it
should not be considered to be of the same nature as
various other size characters in which variation seems to
be continuous, but in which relatively constant gradations
may be isolated, each fluctuating around a particular
mode. But this particular case possesses an advantage
not held by most phenomena of its class, in that there is a
definite discontinuous series of numbers by which each
individual may be classified.
Previous to analyzing the data from pedigree cultures,
however, it is necessary to take into consideration several
facts. In the first place, what limits are to be placed on
fluctuations? From the variability of the progeny of
single ears of dent varieties that have been inbred for
several generations, it might be concluded that the devia-
tions are very large. But this is not necessarily the case;
these deviations may be due largely to gametic structure
in spite of the inbreeding, since no conscious selection of
homozygotes has been made. There is no such variation
in eight-rowed varieties, which may be considered as the
last subtraction form in which maize appears and there-
fore an extreme homozygous recessive. In a count of the
population of an isolated maize field where Longfellow, an
eight-rowed flint, had been grown for many years, 4 four-
rowed, 993 eight-rowed, 2 ten-rowed and 1 twelve-rowed
ears were found. Only seven aberrant ears out of a
thousand had been produced, and some of these may have
been due to vicinism.
On the other hand a large number of counts of the
number of rows of both ears on stalks that bore two ears
has shown that it is very rare that there is a change
T The word fluctuation is used to designate mast somatic changes due to
immediate environment, and which are not inherite
76 THE AMERICAN NATURALIST [Vor. XLIV
greater than + 2 rows. If conditions are more favorable
at the time when the upper ear is laid down it will have
two more rows than the second ear; if conditions are
favorable all through the season, the ears generally have
the same number of rows; while if conditions are unfavor-
able when the upper ear is laid down, the lower ear may
have two more rows than the upper ear. Furthermore,
seeds from the same ear have several times been grown
on different soils and in different seasons, and in each
ease the frequency distribution has been the same. Hence
it may be concluded that in the great majority of cases
fluctuation is not greater than in + 2 rows, although fluc-
tuations of + 4 rows have been found.
A second question worthy of consideration is: Do
somatic variations due to varying conditions during de-
velopment take place with equal frequency in individuals
with a large number of rows and in individuals with a
small number of rows? From the fact that several of my
inbred strains that have been selected for three genera-
tions for a constant number of rows, increase directly in
variability as the number of rows increases, the question
should probably be answered in the negative. This
answer is reasonable upon other grounds. The eight--
rowed ear may vary in any one of four spikes, the sixteen-
rowed ear may vary in any one of eight spikes; therefore
the sixteen-rowed ear may vary twice as often as the
eight-rowed ear. By the same reasoning, the sixteen-
rowed ear may sometimes throw fluctuations twice as
wide as the eight-rowed ear.
A third consideration is the possibility of increased
fluctuation due to hybridization. Shull and East? have
shown that there is an increased stimulus to cell division
when maize biotypes are crossed—a phenomenon apart
from inheritance. There is no evidence, however, that
8 Shull, G. H., ‘‘ A Pure-line Method in Corn Breeding,’’ Rept. Amer.
Breeders’ Assn., 5, 51-59, 1909
* East, E. M., ‘The Distinetion between Development and Heredity in
eee ? AMER. NAT., 43, 173-181, 1909.
No. 518] VARIATION 77
increased gametic variability results. Johannsen’ has
shown that there is no such increase in fluctuation when
close-pollinated plants are crossed. I have crossed
several distinct varieties of maize where the modal num-
ber of rows of each parent was twelve, and in every
instance the F, progeny had the same mode and about the
same variability.
Finally, a possibility of gametie coupling should be
considered. Our common races of flint maize all have a
low number of rows, usually eight but sometimes twelve;
dent races have various modes running from twelve to
twenty-four rows. When crosses between the two sub-
Species are made, the tendency is to separate in the same
manner.
Attention is not called to these obscuring factors with
the idea that they are universally applicable in the study
of supposed continuous variation. But there are similar
conditions always present that make analysis of these
variations difficult, and the facts given here should serve
to prevent premature decision that they do not show
segregation in their inheritance.
Table VI shows the results from several crosses be-
tween maize races with different modal values for number
of rows. Several interesting points are noticeable. The
modal number is always divisible by four. This is also
the case with some twenty-five other races that I have
examined but which are not shown in the table. I suspect
that through the presence of pure units zygotes having
a multiple of four rows are formed, while heterozygous
units cause the dropping of two rows. The eight-rowed
races are pure for that character, the twelve-rowed races
vary but little, but the races having a higher number of
rows are exceedingly variable.
When twelve-rowed races are crossed with those having
eight rows, the resulting F, generation always—or nearly
Johannsen, W., ‘‘Does Hybridization Increase Fluctuating Variabil-
ity?” Rept. Third Inter. Con. on Genetics, 98-113, London, Spottiswoode,
1907.
78 THE AMERICAN NATURALIST [Vou. XLIV
TABLE VI.
CROSSES BETWEEN MAIZE STRAINS WITH DIFFERENT NUMBERS OF ROWS
| Row Classes.
Parents. (Female Given First.) Gen.
DEAE e E 196. | AS. 20
Flint No. 5 100 |
Flint No. 11 4| 387 T 1
Flint No. 24........ 100
Flint No. 15 100 |
Dent No. 6 6| 31| 51| 18| 4
Dent No. 8 Fio bar 36): 124° 24
Sweet No. 53 | 5| 25; 4 |
Sweet No. 54" 25 2 1
o. 5 X No. 53 F, 1 (ERA |
No. 5 X No. 6 Ponne y 8 |
No. 11 X No Piara B |
No. 11 X No. 53 BO eel OE AT ae
No: 24X No. 53 Fo S 8r s3 |
No. 15 X No. 8 Ei al 4) w BE SS
No. 15 X No. 8 (from 10-row ear)..| F, | 14| 15| 28) 9| 1 |
No. 15 X No. 8 (from 12-row ear)..| F, | An 18). 8612.6 84
~ No. 8X No. 5 Ll Bi u |
No. 8X No, 54 (from 12-row ear)..! F, | 11} 251 38 2 1| |
always—has the mode at twelve rows. In one case cited
in Table VI, No. 24 X No. 53, nearly all the F, progeny
were eight-rowed. It might appear from this, either that
the low number of rows was in this case dominant, or
that the female parent has more influence on the resulting
progeny than the male parent. I prefer to believe, how-
ever, that the individual of No. 53 which furnished the
pollen was due to produce eight-rowed progeny. Un-
fortunately no record was kept of the ear borne by this
plant, but No. 53 sometimes does produce eight-rowed
ears.
When a race with a mode higher than twelve is crossed
with an eight-rowed race, the F, generation is always
intermediate, although it tends to be nearer the high-
rowed parent. Only one example is given in the table,
but it is indicative of the class. These results are rather
confusing, for there seems to be a tendency to dominance
in the twelve-rowed form that is not found in the forms
with a higher number of rows. I have seen cultures of
other investigators where 12-row X 8-row resulted in a
* Approximately.
No. 518] VARIATION 19
ten-rowed F, generation, so the complication need not
worry us at present.
The results of the F, generation show a definite ten-
dency toward segregation and reproduction of the parent
types. I might add that in at least two eases I have
planted extracted eight-rowed ears and have immediately
obtained an eight-rowed race which showed only slight
departures from the type. Selection from those ears
having a high number of rows has also given races like the
high-rowed parent without recrossing with it. It is re-
gretted that commercial problems were on hand at the
time and no exact data were recorded. It can be stated
with confidence, however, that ears like each parent are
obtained in the F, generation, from which with care races
like each parent may be produced. Segregation seems to
be the best interpretation of the matter.
These various items may seem disconnected and unin-
teresting, but they have been given to show the tangible
basis for the following theoretical interpretation. No
hard and fast conclusion is attempted, but I feel that this
interpretation with possibly slight modifications will be
found to aid the explanation of many cases where varia-
tion is apparently continuous.
Suppose a basal unit to be present in the gametes of all
maize races, this unit to account for the production of
eight rows. Let additional independent interchangeable
units, each allelomorphiec to its own absence, account for
each additional four rows; and let the heterozygous condi-
tion of any unit represent only half of the homozygous
condition, or two rows. Then the gametic condition of a
homozygous twenty-rowed race would be 8 + AABBCC,
each letter actually representing two rows. When
crossed with an eight-rowed race, the F, generation will
show ears of from eight to twenty rows, each class being
represented by the number of units in the coefficients in
the binomial expansion where the exponent is twice the
number of characters, or in this case (a+ b)°.
The result appears to be a blend between the characters:
80 THE AMERICAN NATURALIST [Vou. XLIV
of the two parents with a normal frequency distribution of
the deviants. Only one twenty-rowed individual occurs
in 64 instead of the 27 expected by the interaction of three
dominant factors in the usual Mendelian ratios. The re-
mainder of the 27 will have different numbers of rows,
and, by their gametic formule, different expectations in
future breeding as follows:
1 AAB BCC = 20 rows.
2 AaBBCC=18 rows.
2 AABbCC=—18 rows.
2 AABBCc=18 rows.
4 AaBbCC —16 rows.
4 AaBBCc—16 rows.
4 AABbCc=—16 rows.
8 AaBbCc—14 rows.
There are four visibly different classes and eight game-
tically different classes. It must also be remembered that
the probability that the original twenty-rowed ear in
actual practise may have had more than three units in its
gametes has not been considered. This point is illus-
trated clearly if we work out the complete ratio for the
three characters, and note the number of gametically dif-
ferent classes which compose the modal class of fourteen
Taste VII
THEORETICAL EXPECTATION IN F, WHEN A HoMmozycous TWENTY-ROWED
MAIZE EAR IS CROSSED WITH AN EIGHT-ROWED
Classes, 8 10 12 14 16 18 20
No. ears 1 6 15 20 15 6 1
rows in Table VII. It actually contains seven gametic-
ally different classes and not a single homozygote. If
this conception of independent allelomorphic pairs affect-
ing the same character proves true, it will sadly upset the
biometric belief that the modal class is the type around
which the variants converge, for there is actually less
chance of these individuals breeding true than those from
any other class.
No. 518] VARIATION 81
The conception is simple and is capable theoretically of
bringing in order many complicated facts, although the
presence of fluctuating variation will be a great factor in
preventing analysis of data. I have thought of only
one fact that is difficult to bring into line. If 844, 8BB
and 8CC all represent homozygous twelve-rowed ears—
to continue the maize illustration—and none of these
factors are allelomorphic to each other, sixteen-rowed ears
should sometimes be obtained when crossing two twelve-
rowed ears. I am not sure but that this would happen if
we were to extract all the homozygous twelve-rowed
strains after a cross between sixteen-row and eight-row,
and after proving their purity cross them. In some cases
the additional four-row units would probably be allelo-
morphie to each other and in other cases independent of
each other. On the other hand, this is only an hypothesis,
and while I have faith in its foundation facts, the details
may need change.
Castle has raised the point that greater variation should
be expected in the F, generation than in the P, genera-
tions when crossing widely deviating individuals showing
variation apparently continuous. If the parents are
strictly pure for a definite number of units, say for size,
a greater variation should certainly be expected in the F,
generation after crossing. But considering the diffi-
culties that arise when even five independent units are
considered, can it be said that anything has heretofore
been known concerning the actual gametic status of
parents which it is known do vary in the character in
question and in which the variations are inherited, for the
race can be changed by selection within it. It may be, too,
that the correct criterion has not been used in size meas-
urements, for, as others have suggested, solids vary as the
cube root of their mass, whereas the sum of the weights of
the body cells has usually been measured and compared
directly with similar sums.
Attention should be called to one further point. Many
characters in all probability are truly blending in their
82 THE AMERICAN NATURALIST. [Vou. XLIV
inheritance, but there is another interpretation which may
apply in certain cases. I have repeatedly tried to cross
Giant Missouri Cob Pipe maize (14 feet high) and Tom
Thumb pop maize (2 feet high), but have always failed.
They both cross readily with varieties intermediate in
size, but are sterile between themselves. We may
imagine that the gametes of each race, though varying in
structure, are all so dissimilar that none of them can unite
to form zygotes. Other races may be found where only
part of the gametes of varying structure are so unlike that
they will not develop after fusion. The zygotes that do
develop will be from those more alike in construction.
An apparent blend results, and although segregation may
take place, no progeny as extreme as either of the parents
will ever occur.
I may say in conclusion that the effect of the truth of
this hypothesis would be to add another link to the in-
creasing chain of evidence that the word mutation may
properly be applied to any inherited variation, however
small; and the word fluctuation should be restricted to
those variations due to immediate environment which do
not affect the germ cells, and which—it has been shown—
are not inherited. In addition it gives a rational basis
for the origin of new characters, which has hitherto been
somewhat of a Mendelian stumbling-block; and also gives
the term unit-character less of an irrevocably-fixed-entity
conception, which is more in accord with other biological
beliefs. ;
COLOR INHERITANCE IN LYCHNIS DIOICA L.
DR. GEORGE HARRISON SHULL
Two years ago I showed that in Lychnis dioica L. the
purple-flowered form behaves in normal Mendelian man-
ner when crossed with the same type or with the typically
white-flowered form of the same species (Shull, 1908).
In subsequent work it has been discovered that the
purple-flowered plants do not form a single unit-group,
but that there are at least two distinct types, one of
which has more bluish-purple flowers, the other more
reddish-purple. No notice had been taken of such varia-
tion in the color characters until last year, although it
had been observed that there was some variation in the
intensity of color in different plants, and these had been,
to a slight extent, recorded in terms of intensity, €e. g.,
as ‘‘light,’’ ‘‘medium’”’ and ‘‘dark.’’ Last year several
individuals were observed so noticeably distinct because
of the bluish character of their flowers, that an effort was
made to determine the relationship of this light bluish-
purple color to the more common reddish-purple, and
several crosses were made representing the combination
of ‘‘blue’’ and ‘‘red,’’ using a single red-flowered indi-
TABLE I
TA: Cross. Red. | Blue. | White.| Theoretical Result. Sead
0845 | Blue X Blue 1 83 0 0: 84: 0 031:0
0846 | Blue X Red 47 ) 48: 48: 0 Lerso
0844 | Blue X White} 52 0 46 49: 0: 49 1:0:1
SR es| 92 | 1 | 68: 8: 0 | 3:1:0
0848 | Red X Blue 27 32 27 32 ee, v A v- 3:3:2
0847 | Red X White 53 0 46 50: 0 49 1:03)
0875 | White X Blue 34 2 41 25: 25: 49 1:1:2
0876 | White X Red 31 20 0 3e 138: 0 B: I: 0
Total 313 | 230 | 161 | 310 : 225 : 169
1 Read before the Botanical Society of America at Boston, December,
909.
83
84 THE AMERICAN NATURALIST [Vou. XLIV
vidual as the mother in one series of crosses, and a single
blue-flowered individual as the mother in another series.
The same blue-flowered and red-flowered plants were also
erossed at the same time with white-flowered plants.
The actual and theoretical results of these eight crosses
are given in Table I.
In addition to these families which were bred in such
a way as to allow the definite working out of the gametic
formule of the parents and the theoretical results, bluish-
flowered plants were also observed in a number of other
pedigrees. In some of these families only a small pro-
portion of the individuals had their tints recorded, as
they were being especially studied with other objects in
view. Such fragmentary records are of no special value
in this connection, of course, and they will not be pre-
sented; but in Table II. are given all those pedigrees in
which approximately all the purple-flowered offspring
were recorded either as ‘‘blue’’ or ‘‘red.”’
In'this second table it is impossible to vouch for the
correctness of the suggested theoretical results, as the
gametic formule of the parents are in each case very im-
perfectly known. The column of theoretical results is
constructed simply by using that one of the available
theoretical ratios which fits most accurately the observed
facts. When numbers are so small, mere inspection can
not determine with certainty which is the correct theo-
retical ratio. Thus in No. 08168 the empirical ratio,
19:11:31, is almost equally well referred to either of the
available ratios, 1:1:2 and 3:1:4, as it stands about mid-
way between them. Notwithstanding the fact that igno-
rance of the gametic composition of the parents in this
second table makes it impossible to decide in all cases
what ratio should have been expected, the results har-
monize well throughout with those which comprise Table
I., where the theoretical ‘‘expectation’’ is definitely
own.
All of the crosses recorded in these two tables seem to
be typically Mendelian, with the bluish-purple color hypo-
No. 518] COLOR INHERITANCE 85
TABLE II
|
a | Cross. | Red | Blue. | White. ee ecu | Ratio
De | | Invoked.
0850 Red X Red -|` 67, 0 o | 67: 0: 0|1:0: 0
0851 Red X White} 40 13 0 ODB: 08:1: 0
0852 | White X Red w A e e Sosa:
0853 Red X Red 07 a8 m: Ot; 1 82.0: od
0855 |Red X Red | 105) 0 | 0 | 105: 0: K iros 0
56 Red White) 39 18 | 39 36 : 12 Bir 4
0857 | Red Red 64| 14 | 25 58: 19: 2 9:3: 4
58 Red S White} 17, 12 | 33 Bop Hii?
0859 Red X White yee eee T To OF WES 09.9
0860 Red X Red Te Bi ti: OF 9418 20 l
0861 Red X White 0 0 3B 0s 01:0: 0
0862 Red << Re 101, a o 1: Oe Fn
0863 | Red X Re 30) 0 6 g: 0: 9l 3:0. 1
0864 | Red White [ca t b Glion 8
0865 | White X Red ee: 6 B 6: esb:
0866 | White X Red 37} 0 | 29 S822 MEO ad
0867 | White xX Red 5| 0 | 16 20: O: 21/1:0: 1
08 XE 74, #0 12 Ot 0s. 8h) 3287 1
086: | e x hite 44 0 49 iz: 0: 461.2::.0:2 1
0871 | White X Red 30 0 | 54 a 0:6313: 0:6%
882 | White X Red 93} 8 | 43 21: 7%: 461 9%: 3:20
0884 | White X Red 26, 8 | 40 a: O: 3713:11: 4
08100 | White X Red 444 0 | 45 44: 0: $ 1:0: 1
08105 | White X Red 291 0 | 29 29: 0: 11:0: 1
0815 d X White 28 27 | 35 23 H:A iii: 2
0815 XR 25 0 G: D: 010:0
08156 | White X Red 29| 16 | 34 30: 10: 9 3:1: 4
161 | Red X Red i4 13 | 18 42: 14,: 19| 9:3: 4
08162 |Red White) 48 0 | 45 47 : beh 1
08168 | White X Red 19} 11 | 31 16: 16: 31] 1:1: 3
0817. X Red w 0 29 mM: 0 5} 3:0: 1
08177 |Red X Red D omi Te 86s 4
08178 | Red S White 47, 0 | 47 | 47: 0: 47/120: 1
| Total 1,426 144 | 806 | 1,382: 143 : 851 |
static or ‘‘recessive’’ to the red. This is one of the first
cases of this kind which has appeared, as heretofore the
bluish colors have quite generally been found epistatic to
the reds. The most important studies which have been
made relating to the inheritance of the anthocyan
colors are those of Bateson (1902, 1905, 1906, 1909)
and his co-workers, on Lathyrus and Matthiola, Miss
Wheldale (1907) and Baur (1908) on Antirrhinum, and
Tschermak (1901, 1904) on Pisum and Phaseolus. In
all of these genera as well as in Clarkia and Salvia
(Bateson, ete., 1905), the more bluish anthocyan color
is epistatic to the reddish anthocyan. Bateson (1909, p.
41) states in one place, that in Primula Sinensis ‘‘blue
86 THE AMERICAN NATURALIST [Vow XLIV
is hypostatic to all the red shades,’’ although the magenta
colors are shown to be epistatic to red. This isolated
statement regarding the blue color in Primula Sinensis
is not supported by any data, and I do not know the
chemical relation between it and the magenta colors.
Miss Wheldale (1909), who discusses at some length the
color series in Primula material secured from Bateson
and Gregory, makes no mention of the occurrence of blue,
though she ascribes the production of magenta and
crimson to the action of a ‘‘bluing factor’? upon red
anthocyan. |
Upon comparison of my bluish-purple Lychnis with
the colored plates of Primula given by Bateson (1909,
p. 294) I think the Lychnis color should be classed as a
light magenta rather than a blue, as there is a decided
reddish element in this Lychnis color. If Bateson’s iso-
lated statement that ‘‘blue is hypostatic to all the red
shades’’ in Primula is correct, then that color corre-
sponds in its behavior with this light magenta color in
Lychnis. I have not made a thorough investigation of
the chemical relations of the two types of purple in
Lychnis, but have demonstrated by a few preliminary
tests that the reddish-purple color is converted to bluish
when treated with alkalies, and that the light bluish-
purple is made as bright red as the red-purple type on
treating with weak acids, thus indicating a very simple
relation between these two colors.
Although the relation between the two types of color
in Lychnis is just the reverse of that exhibited by prac-
tically all other plants in which similar colors have been
studied, I am led to essentially the same conclusions re-
garding the method of color determination, as those de-
rived from the extensive studies which have been made
on Lathyrus, Matthiola, ete. The production of the
‘‘lowest stage’’ of color, i. e., the color which results from
the combined action of the least number of genes, is due
to the interaction of two independent factors or genes,
either of which produces no color when not associated with
No. 518] COLOR INHERITANCE 87
the other. In order to produce a second stage of color it
is necessary to assume the occurrence of a third gene
which can make its characteristic color-reaction apparent
only in the presence of the other two. Thus in Lathyrus,
etc., it was assumed that two factors, R and C, are neces-
sary to the production of a red anthocyan color, and that a
third factor, B, modifies this color to bluish. This as-.
sumption requires that the presence of each of these three
genes be dominant over its absence. An alternative as-
sumption might have been made, viz., that the absence of
the third factor is dominant over its presence. Then the
lowest grade of color would be a blue color produced by
the simultaneous presence of B and C, and the red color
would appear only when R is present in the homozygous
state.
Last year in my discussion of the presence and ab-
sence hypothesis (Shull, 1909) it was pointed out that it
would be impossible in many eases to determine ‘‘ whether
red flowers are blue flowers with an added factor for
acidity or whether blue flowers are red with an added
factor for alkalinity,’’? and also that ‘‘it is conceivable
that both these situations may be presented in different
species.” The color characters in Lychnis give a very
good illustration of these statements.
If we assume the dominance of presence over absence,
the lowest grade of color—the bluish—is formed by the
combined action of two genes, B and C, the one probably
representing, according to the studies of Miss Wheldale
(1909), the capacity to produce a chromogen of the
flavone series, the other representing the production of
an oxidase. The red color is in this case produced by an
added factor, R, which modifies the bluish color produced
by B and C. The R may be perhaps an acidifier, a re-
ducing agent, or a partial inhibitor of the oxidizing
action of B. This method of explaining color inheritance
in Lychnis presents an interesting reversal of the places
occupied by R and B when compared with the situation
in other plants.
88 THE AMERICAN NATURALIST [Vou.XLIV
If, on the other hand, the assumption be made that, in
Lychnis, absence of B is dominant over its presence, the
relative positions of R and B may remain the same as in
Lathyrus, Matthiola, ete. For in this case R and C will
be the two factors necessary to the production of red
anthocyan and B the ‘‘bluing factor’’ which is added to
it to form bluish anthoecyan, the difference between
Lychnis and Lathyrus being simply that the B which
may be looked upon perhaps as a factor for alkalinity or
for an oxidizer, is too weak in its activity in Lychnis to
produce its characteristic effect except when present in
double quantity or strength, as it is when in the homozy-
gous State.
The data now at hand do not make possible a decision
as to whether presence, or absence of the color-modifier,
is dominant in Lychnis, as each of these assumptions may
be shown to fit all the facts involved in Table I. The
gametic formule of the six plants involved in these eight
crosses are presented in Table II., to enable a compari-
son of the two methods of explanation.
TABLE III
Resultant
Ped B + C Produces Blue. R + C Produces Red. atio
No Crosses, Presence of R Dominant. | Absence of B Dominant.| Red: Blue:
White..
oe ts a X Blue BCCX BEC BBRCCX BBERO 0:1: 0
0846 BI e X Red BOG X Ey CC BBRCC X BRRCC| 1:1: 0
0844 Blue X White | BCC X RR (CC?) BBRCC x CC 10:1
0849. | Red X co BBB Cs soe BROX BRECC Seles?
0848 Red XB Cx BBC BRC X BBRRC oA 8 ue
oe Red xX White ger” BRC x CC F204
0875 White X Blue RB(B?) B BX BBRRC Ioir?
0876 Whi te X Red | | RB(B?) S BRED | BSB REO Olik: G
The fact now demonstrated that the purple color in
Lychnis is due to the presence of at least three distinct
genes instead of only one, as originally assumed by me,
has served to elucidate several difficulties which had
been encountered. It may be recalled that a rather
large range of supposedly fluctuating variability in the
No. 518] COLOR INHERITANCE 89
percentage of purple-flowered individuals in families re-
sulting from crosses of purple with white was shown to
form a normal probable error curve, thus conforming
very well with the Mendelian hypothesis that gametes
of different alternative composition unite according to
the laws of chance. While this conclusion is not in any
way opposed by my later studies, it is now known that
a portion of that apparently fluctuating variation may
have been due to the occurrence of a mixture of sev-
eral different ratios. In accordance with the present
demonstration that the purple color is due to three fac-
tors, the combined action of two of which are necessary
to the production of any color and the addition of a third
for the modification of this color, a cross between white
and purple must give either all purple, or purple and
white in any of the following ratios: 3:1, 1:1, 3:5, or 1:3,
though the ratio 1:1 occurs much more frequently than
any of the other possibilities. In other words, without
any fluctuation at all, purple-flowered individuals, when
mated entirely at random with white-flowered individuals,
should produce progenies consisting of 25, 37.5, 50, 75 or
100 per cent. purple-flowered offspring, instead of only
50 or 100 per cent.
I have in several cases found purple-flowered individ-
uals among the offspring of two white-flowered parents.
Such oceurrence was entirely incomprehensible to me ex-
cept on the basis of an error in technique. It now be-
comes obvious that white crossed with white must oc-
casionally give various proportions of purple-flowered
offspring. Some such crosses will give all purple while
others will give purple and white in ratios 1:1, 3:5, or
1:3, although a frequent result will be a progeny of all
white, which latter alone was expected under the con-
ception that the purple color was due to the presence of
a single gene. Although I have reared many families in
which both parents were white, I have almost invariably
obtained a progeny of all whites, but this is undoubtedly
due to the fact that such crosses of white with white were
90 THE AMERICAN NATURALIST [Vovu. XLIV
nearly always made between sibs in wholly white-flow-
ered families. Such crosses are necessarily homozygous
with respect to the absence of one (or both) of the two
genes whose joint action is necessary to the production
of color. Crossing of white-flowered individuals of dif-
ferent parentage or of white sibs in hybrid families will
doubtless quickly demonstrate the production of purple-
flowered offspring by white-flowered parents, in the ratios
required by theory.
SuMMARY
The purple color in Lychnis dioica L. is a compound
character, produced by the interaction of three distinct
and independent genes in a manner exactly analogous
to the similar colors in Lathyrus, Matthiola, ete.
The two types of purple color present in different in-
dividuals are a reddish and a more bluish-purple, the
former being changed to blue by treatment with alkalies,
and the latter changed to red by the addition of weak
acids.
The bluish or alkaline color is hypostatic to the reddish
or acid color, this being the reverse of the condition found
in all other plants containing similar series of colors
which have thus far been reported, unless possibly an
isolated statement should prove correct that in Primula
Sinensis ‘‘blue is hypostatic to all the red shades.’’
It is impossible to determine at present whether this
reversal of the relation between bluish and reddish
anthocyan results from the occurrence of positive char-
acters for both alkalinity and acidity, or whether only
one of these exists as a positive character and the alter-
native color is produced when this positive color-modifier
is in the heterozygous state, the latter situation involv-
ing the dominance of absence over presence.
_ The rather wide fluctuation in the percentage of purple-
flowered families resulting from the cross of heterozy-
gous purple with white (i. e., supposedly DR X R), re-
ported in a former paper, may have been due in part to
No. 518] COLOR INHERITANCE 91
the mixture of the ratios 3:1, 1:1, 3:5 and 1:3, all of
which are expected Mendelian results, on the basis of
present knowledge of the compound character of Lychnis
colors. |
Crosses between white-flowered plants should, not in-
frequently, result in progenies of all purple-flowered off-
spring or of purple and white in the ratios 1:1, 3:5, or
1:3. These results have not yet been found, owing no
doubt to the fact that my crosses between white and
white have been almost invariably made between sibs in
wholly white-flowered families.
STATION FOR EXPERIMENTAL EVOLUTION,
COLD Spring HARBOR, LONG ISLAND,
November 19, 1909.
LITERATURE CITED
1909. Bateson, W. Mendel’s Principles of Heredity, pp. xiv + 396, 1909.
Cambridge, University Press.
1902. Bateson, W., and Saunders, E. R. Experimental Studies in the
Physiology of Heredity, L Reports to the Evolution Committee
of the Royal Society.
1905. Bateson, W., Saunders, E. R., and Punnett, R. C. Reports to the
Hvolutibn Committee of the Royal Society,
1906. Bateson, W., Saunders, E. R., and Punnett, R. c. Ibid., III.
1908. Baur, E. Einige Ergebnisse der experimentellen Vererbungslehre.
Beih. z. Med. Klinik., 4: 265-292,
1908. Shull, G. H. Some New Cases of Mendelian ‘Tnhorianee: Bot. Gaz.,
45: 103-116, February, 1908.
1909. Shull, G. H. The ‘‘ Presence = Absence’? Hypothesis. Amer.
Nat., 48: 410-419, July, 1
1901. Tschermak, E. Weitere ee über kroua der
Merkmale bei Kreuzung von Erbsen und Bohnen. Ber. Deutsch.
Bot. Gesell., 19: Heft 2, 1901.
1904. Tschermak, E. Weitere Ton an Erbsen, Levkojen und
Bohnen. Zeitschr. f. d. landw. Versuchsw. in Oesterr.
1907. ee Miss M. On t the Inheritance of Flower-color in Antir-
um majus. Proe. Roy. Soc., 79: 1907.
1909. Siera Miss M. On the Nature of Anthocyanin. Proc. Cam-
bridge Phil. Soc., 15 (pt. II.): 137-168, 1909.
IS REGENERATION A REPETITION OF THE
ONTOGENETIC AND PHYLOGENETIC
PROCESSES?
SERGIUS MORGULIS, A.M.
Facts are as unaffected and permanent as the universe.
They are always present, whether we know them or not.
Theories, on the contrary, are transitory conceptions,
products of the intellect striving to comprehend the
outer world. As a verbal expression of the unity under-
lying the overt diversity of phenomena and things, and
as a mental picture of the connection between things,
theories may be either perceived or imagined, a step
towards absolute truth or a profound fallacy. Its fate
depends wholly upon compliance with the facts, and it
can not, therefore, be used as a criterion of value of the
facts. Theories may ultimately be revised or discarded
—facts remain forever.
With this commonplace in mind, we can clearly see
that the question before us—namely, is regeneration a
repetition of the processes of ontogeny and phylogeny ?—
is a matter of theory. As such, it is a much-debated sub-
ject which has been so often and so ably discussed in the
past by several writers, that I should, perhaps, refrain
from adding my quota to the dispute. But it has lately
been called to my attention by an admirable monograph,
by K. N. Davydoff.! As Davydoff writes in Russian, his
work is practically inaccessible to American readers.
Considered from a purely technical standpoint, the
monograph leaves little more to be desired. It is sup-
plied with a large number of well-finished figures, and
the text is lucid and concise. I should use only terms of
praise if I were to speak on that score. I shall, however,
*K. N. Davydoff, ‘‘Observations on the Process of Regeneration in
Enteropneusta,’’ Mem. de l’Académie Impériale åd. Sc. de St.-Pétersbourg,
Vol. 22, No. 10, pp. 1-120, 1908 (Russian).
92
No. 518] REGENERATION 93
not concern myself with this side of the matter, as it is
my prime object in the present article to scrutinize Davy-
doff’s theoretical position.
On the very first pages Davydoff states the main
article of his creed: that the fact that new organs, in the
process of regeneration, originate from the same layers
from which such organs originated embryologically
proves that the two processes are parallel in cause.
Since the hypothesis of the repetition of the phylo-
genetic processes in regeneration necessarily rests upon
this assumption, as a major premise, it may be well, in
the first instance, to examine closely its validity. This
plan is preferable also because Davydoff himself in im-
parting his data and defending his thesis follows a sim-
ilar course.
The reader is doubtless familiar with the way a com-
parison of the two-layered gastrula with an adult Cæ-
lenterate had ultimately grown into Haeckel’s celebrated
‘“Gastrea-theorie.’’ This broad embryologieal concep-
tion, purporting to bind the entire animal kingdom with
bonds of genetic relationship, postulates the homology of
adult organs differentiated from similar germ-layers in
the embryos. So fascinating was the application of this
greatest biological generalization that the overweening
confidence it bade became in time a source of grievous
blunders. Contradictions have arisen on the ground of
striking differences in the origin of organs in develop-
ment and in budding, as was discovered to be the case
in Bryozoa and in Tunicates. Likewise the discrepancy
often observed between the methods of organ-formation
in ontogeny and regeneration tended further to under-
mine credulity in the theory and the value of the germ-
layers as a criterion of homology. Indeed, so seriously
was this aspect of the theory threatened that conserva-
tive men, like L. Schultze, anxious to safeguard it from
impending disrepute, were obliged to eliminate instances
of budding and of regeneration from a consideration of
homologies.
94 THE AMERICAN NATURALIST [Vou. XLIV
. Die Entstehung eines Organs durch Regeneration oder Knospung
keinen Anhaltspunkt giebt zur Beurteilung des Morphologischen Wertes
seiner Entwicklung aus einem Keimblatt, d. h. die Verwertbarkeit der
Keimblatt-Herkunft eines Organs fiir die Frage seiner Homologie mit
einem anderen Organ, dessen Keimblattursprung ebenfalls bekannt ist,
wird durch die Knospungs- und Regenerations-befunde in | keiner Weise
beeinträchtigt. (L. Schultze, p. 331.)
The inextricable contradictions which sprang from the
tenets of historical and morphological significance of the
germ-layers called forth even a more vigorous reaction.
Braem subjected the theory to a thorough and relentless
critique revealing its inadequacy. ‘‘Der Begriff Keim-
blatt,’ he proclaimed, ‘‘ist gar kein morphologischer
sondern ein physiologischer Begriff. Keimblätter sind
Organbildner.’’ And further, he introduced the prag-
matic principle that -
. Ein Schicht ist nicht deshalb Entoderm weil sie das innere Blatt
einer Gastrula ist, sondern sie ist Entoderm weil sie den Darm bildet,
weil sie die physiologische Charaktere des Darmblattes entweder bereits
besitzt oder doch im Laufe der ferneren Entwicklung annimmt.
Massgebend ist nur die organbildende Potenz, die Funktion der doit
schicht. (Braem, p. 431.)
While embryologists were thus questioning the impor-
tance of the germ-layer as a criterion and in fåct were
at a loss to know what was meant by a germ-layer, stu-
dents of the histogenetic processes in regeneration were
accumulating evidence to the effect that the new tissues
generally arise from corresponding old tissues, and,
consequently, from the same germ- -layers from whic
those tissues had been differentiated in development.
Although the evidence is based largely upon the investi-
gation of the regenerative process in worms, the facts
relating to this animal group as they are stated by vari-
ous authors are too much at odds with each other to be
of any real worth, at least so far as the problem of the
relation between regeneration and ontogeny is concerned.
This may seem a very strong statement, but it is justi-
fied by the frequent contradictions which one encounters
in reviewing the literature. To be specific, I might men-
No. 518] REGENERATION 95
tion the case of Lumbriculus. The histogenesis of the
regenerated organs in this worm was studied very ex-
tensively by at least four investigators. There is
scarcely a point of any importance upon which all are
unanimously agreed. Unless one shares Davydoff’s
rosy optimism that ‘‘ whatever is last is best,” and that
the latest contribution to the subject is necessarily the
truest, the non-committal attitude of skepticism would
seem far preferable.
Furthermore, the histological studies of the regenera-
tive process have likewise revealed certain striking devi-
ations from the usual course of things. Wolff’s re-
searches of the regeneration of the lens in salamanders
showed that in regeneration the lens is formed by a
method entirely different from that observed in embry-
onic development. In the embryo it arises as a thicken-
ing of the ectoderm covering the optic cup, while in re-
generation—‘‘Der Obere Irisrand ist nämlich offenbar
die zweckmissigste stelle fiir die Enstehung der Linse.’’
Hazen discovered that in the anemone Sagartia the re-
generation of the esophagus involved some important
departures from the ontogenetic process.
In small pieces the esophagus regenerates as an invagination of
mesoglea and endoderm in the shape of an inverted cup, in which the
mesoglea forms the middle layer, and which is covered on both outside
and inside by entoderm. The ectoderm takes no part in the regenera-
tion of the cesophagus. :
Margaret Reed found that the muscles of a regener-
ating appendage in crustacea originate entirely from
ectodermal cells. ‘‘When the first leg of the crayfish is
thrown off at the breaking joint, no muscles are injured,
and the muscles for the new leg are formed from cells
proliferated by the ectoderm. In the hermit crab also
the muscles of the new leg are formed by ectodermal
cells.’’ In ontogeny the muscles originate from endo-
derm.
The last discovery is of particular importance, not
only on account of the different methods of muscle-for-
96 THE AMERICAN NATURALIST [Vou. XLIV
mation in development and regeneration which it brought
to light, but because it calls into question the conception
of the determined specificity of tissues. And in point of
fact, the problem of the relation between regeneration
and ontogeny ultimately resolves itself into this wider
problem of the specificity of tissues. In the crayfish
and hermit crab cells, which under ordinary conditions
of development never give rise to muscles, apparently
have the potentiality to do so under certain circum-
stances.
The exceptional cases, alluded to above, are not of the
kind that would tend to corroborate the rule. On the con-
trary, they tend to turn the whole question topsy-turvy.
It rests with the adherents of the view that regeneration
and ontogeny are parallel processes to bring forth a
creditable explanation of these facts to fit them into their
theory, for as long as they remain undisputed facts they
must likewise remain the unapproachable stronghold of
skepticism.
Davydoff in his recent monograph traced with great
skill and painstaking care the history of each regenera-
ting organ of Ptychodera. This laborious investigation
led him to conelude that ‘‘the study of regeneration in
Enteropneusta entirely corroborates the hypothesis that
... all organs and tissues regenerate from elements of
the same germ-layers from which they also developed in
ontogeny’’ (p. 78).
This conclusion is adopted ‘‘even though at times
there is no complete resemblance to the ontogenetic
process’’ (ibid.).
The reservation is specially noteworthy since in
another place we read the following:
It must be pointed out that many departures from the general method
of regeneration to be described further are of frequent occurrence; in
fact, it might be said that each particular ease presents some character-
istie peculiarity: the details of the regenerative process vary indefi-
nitely. . . . It is necessary, however, to account for all the conditions
of each case in order to interpret any deviation from the typical; at
present this is an impossible task. Only by making due allowance for
No. 518] REGENERATION OT
variations within the widest limits, it may be possible to delineate the
normal course or type of regeneration (p. 16).
Without any intention on my part to detract from
Davydoff’s merits of having accurately ascertained the
facts of the regeneration of Enteropneusta, it neverthe-
less seems to me that the manner of his argument is more
entertaining than convincing.
Here, for instance, are samples of his reasoning. In
Ptychodera (Entero ta) the new cœlome regener-
ates from elements of the old ccelome, i. e., the new
mesoderm arises from old mesoderm. So far, so good.
Davydoff, however, is not fully satisfied with this achieve-
ment, as he is determined to prove to his reader that the
parallelism between ontogeny and regeneration is of a
far more subtle nature; but he encounters a stumbling
block in that the ccelome in ontogeny arises as an evagi-
nation of the primitive endoderm. In the regeneration
of the cœlome, however, the endoderm takes no direct
part. Is that to be regarded as a discrepancy between
ontogeny and regeneration? Sensible men might say
that since the old cœlome had been differentiated from
endoderm, therefore, the new cœlome regenerating from
the old cclome is likewise of endodermal origin, and
would let the matter rest there. Davydoff is not con-
tented with this sort of proof. He finds that in Balano-
glossus kowalewskii the coelome of the collar arises not
as an independent outgrowth from the primitive gut, but
is formed by proliferation of cells from the cclomic
pouches of the body. In other words, in Balanoglossus
kowalewskii the eclome of the collar originates not
directly from the endoderm, but indirectly from the al-
ready differentiated celome of the body. Is not this a
wonderful identity between the processes of regenera-
tion and ontogeny in Ptychodera and Balanoglossus?
But how is it with the ecelome of the proboscis? In
Ptychodera it regenerates by proliferation of cells from
the ecelome of the collar. Does it arise in the same man-
ner in the course of ontogeny? Davydoff appears a little
98 THE AMERICAN NATURALIST [Vou. XLIV
embarrassed on this score. Balanoglossus kowalewskii,
which served him such a good turn in his contention re-
garding the subtle similarity between the regeneration
and development of the ccelome of the collar, is of no
avail for the present purpose. In Balanoglossus kowa-
lewskii the cælome of the proboscis arises immediately
from the primitive gut as an unpaired outgrowth. But
what does it really matter how this end is accomplished
in Balanoglossus kowalewsku?. And why, proceeds Davy-
doff, should we be hasty in emphasizing too strongly this
difference between ontogeny and regeneration, as long as
we know absolutely nothing concerning the formation of
the eccelome of the proboscis in the ontogeny of Enterop-
neusta? :
Davydoff’s criticisms, after the fashion of his argu-
mentation, is superficial and unsubstantial. His criti-
cism of Morgan misses the point completely. Attacking
Morgan as the foremost leader of the opposite camp, and
as one who gave the ablest expression to the skepticism
concerning the supposed causal relation between proc-
esses of regeneration and ontogeny, Davydoff remarks:
We must agree that Morgan’s arguments as well as his whole critique
are exceedingly weak. While referring in the literary index [Regenera-
tion, 1907] to a number of works contradicting his views, he none the
less makes no mention of them in the text, but exalts a few facts, which
are in reality of no great significance, and often even count directly
against Morgan’s own contentions (p. 65).
This statement requires some comment, so unjustified
does it appear to me. In the first place, that Morgan re-
fers to works which take the other side in the disputed
question is a good warrant that the question has not been
considered one-sidedly. Davydoff, on the contrary, for
some esoteric reasons and without any excuse whatever,
closes his eyes upon the facts which challenge his hypoth-
esis. Furthermore, Davydoff’s allusion to the work of
Abel, as one of a number of works supporting his as-
~- sumptions, might likewise be questioned upon Abel’s
= own authority. For Abel, enumerating the different
No. 518] REGENERATION 99
ways of the regeneration of the end-gut, states definitely:
Hinsichtlich des Verlaufs der Regeneration braucht jedoch durchaus
keine mit den ontogenetischen Processen iibereinstimende Bildungs-
weise des Enddarmes stattzufinden.
In the second place, Davydoff’s criticism is unjust be-
cause it arises from a lack of appreciation of the sound-
ness of Morgan’s skepticism. As a matter of fact, Mor-
gan and his school do not deny that there is at times a
very marked similarity between the methods of regenera-
tion and ontogeny. Morgan is willing to go even further
than that, and to admit a complete identity of the two
processes. His position may be best formulated in his
own apt words:
The mistake, I think, is not in stating that the two processes are
sometimes similar, or even identical, but in stating the matter as though
the regenerative process repeats the embryonic method of development’
(p. 213).
I dwell at such great length upon the question of the
causal relation between regenerative and ontogenetic
processes because, unless there is reasonable occasion
for disbelieving it, the theory of the repetition of phylo-
genetic processes in the course of regeneration must not
be dodged, as the next logical step. In the foregoing I
have been emphasizing particularly the facts opposed to
the theory not from any prejudiced neglect of the facts
apparently favorable to the theory, but simply to show
that the question of the connection between ontogeny
and regeneration is far from being firmly established.
To build upon this as a foundation elaborate theoretic
superstructures is like erecting a magnificent edifice upon
a foundation of quicksand.
But if regeneration repeats the ontogenetic process, as
is claimed by some, what is the significance of the oc-
easional departures of the end result of regeneration
from that of normal development? The believers in the
theory have a ready answer. Those are obviously cases
of atavism, they say. Just as the connection between
*Ttalics are mine.
100 THE AMERICAN NATURALIST [Vou. XLIV
ontogeny and phylogeny is obscured by the ccenogenetic
peculiarities of the former, so likewise the connection
between ontogeny and regeneration is frequently ob-
scured by the palingenetic peculiarities of the latter. To
quote: ‘‘Die Uebereinstimmung (zwischen Regeneration
und Embryonalentwicklung) bezieht sich gerade auf
palingenetische ziige, wärend cenogenetische viel leichter
eliminiert werden’’ (E. Schultz). The application of the
principle of atavism to phenomena of regeneration has
been in vogue for nearly a quarter of a century, and
Davydoff also records what he considers cases of atavism
in the regeneration of Ptychodera, such as: the forma-
tion of two nephridial ducts instead of one; the failure to
regenerate on the part of the ectodermal duct of the
nephridium; the regeneration of a double instead of a
single pericardial sac, etc. 3
The novelty of Davydoff’s work consists in the at-
tempt to give to the principle of atavism practical
application. If regeneration proceeds by more primi-
tive methods, why not avail oneself of this opportunity
to throw light upon such points of animal morphology as
are obscured by the ccnogenetic methods of develop-
ment? To Davydoff belongs the full credit for having
ventured to accept this logical consequence of the preced-
ing propositions. We shall return to this question later.
At this moment I wish to examine the validity of the
so-called ‘‘atavism’’ theory in regeneration.
The defects of this theory are twofold—the theory is
not self-consistent, and, moreover, in the majority of
cases it takes for granted what ought first to be proved.
The inducement may be strong to interpret, for instance,
the type of sealing on regenerating tails of lizards, totally
different from the normal for the given genus and yet
similar to that of another genus, as a ‘‘throwing back’’
to some common ancestral condition. The appearance
of dorsal stripes on the regenerating tails instead of the
usual annuli might with like justice be conceived as a
‘throwing back.” But while maintaining the atavistic
No. 518] REGENERATION 101
nature of the former, Boulenger finds no occasion for
applying the theory to the latter case.
Barfurth finds that the axolotl often regenerates five
fingers on an amputated limb. Considering the complex-
ity of the regenerative mechanism, the frequent occur-
rence of abnormalities, and, as Barfurth himself points
out, that ‘‘ Modus und Product der Regeneration von der
Art der Operation abhängig sind’’ it would seem that the
regeneration of five fingers is of no more value from the
point of view of the salamander’s phylogeny than the
double paw of a cat is for the appreciation of its phylog-
eny. Yet he is ready to believe that ‘‘die verhältnis-
missig häufige Regeneration einer fiinffingerigen Hand
beim Axolotl ist ein Rückschlag auf die ursprünglich
normalerweise fiinffingerige Hand der Amphibien.”
It will, perhaps, not be devoid of interest to note that
Ridewood, who studied the regeneration of the limb of
the toad, expresses himself quite differently upon this
question. ‘‘While in animals other than Anura,’’ he
says, ‘‘structural differences between the regenerated
and the normal limb may be explained as phenomena of
atavism, there is no evidence of such phylogenetic re-
version in the regenerated limb-skeleton of the Anura
under consideration. ’’
It should be obvious that it is not sufficient to point to
some abstract ancestor, an imaginary conception, but
that the real ancestor must be known in order that the
genuineness of the reversion may be established beyond
doubt. It is absurd to apply the term ‘‘reversion’’ and
‘‘atavism’’ to sporadic growths, not represented in the
normal development, of which the factors are, in most
eases, entirely unknown to us.
The inconsistency ascribed to the theory may be
further exemplified by the following instances. In tra-
cheate insects, according to Brindley, the reproduced
portion of an amputated appendage is invariably unlike
the normal. In Blattidæ fewer than five tarsi regenerate,
and the size of the parts is likewise different from the
102 THE AMERICAN NATURALIST [ Vou. XLIV.
` normal. Is the reduced number of tarsal joints in the
regenerated appendages an indication of reversion to a
more primitive condition? No advocate of the atavism
theory would be likely to go so far as to oppose the au-
thoritative opinion of entomologists which assumes the
five-jointed condition as the primitive one. Yet even on
its full face value this fact of dropping out of joints is in
no sense different from the fact of the addition of an
extra finger in the regenerating limb of a salamander
which is professed to be a reversion. And, to be consist-
ent, should we not also suppose on the basis of Herbst’s
discovery of the regeneration in crustacea of antennz
in place of extirpated eyes that the ancestors of these
animals at the dawn of their history had no eyes, and
that the antenna is the precursor of the eye?
One of the most amusing attempts to mould a regen-
erated structural peculiarity into the picturesque shape of
an ancestral structure of overwhelming antiquity is that
of Schimkewitsch, who very sagaciously interprets the
regeneration of an amphibian lens in terms of atavism.
As already mentioned in a previous section of the paper,
the amphibian lens regenerates not from the skin but from
the iris, which is a marked departure from the develop-
mental process. This fact leads Schimkewitsch to sup-
pose that the paired eyes of vertebrates must have primi-
tively been similar to the epiphysis of reptiles, com-
monly known as the pineal organ or eye. This pineal
organ possesses a lens-like structure which is. formed by
the thickening of the outer wall of the cup. The purely
superficial resemblance of the lens regenerating from
the iris of the eye and the lens-like thickening of the
pineal organ is the starting point of Schimkewitsch’s
hypothesis. He says:
Ursprünglich die paarigen Augen eine ebensolehe Linse besassen wie
wir sie im unpaaren Augen der Hatteria sehen, d. h. hervorgegangen
aus der Wand der Augenblasse selbst.
It is needless to insist that, in the usual fashion, the
author of the hypothesis is appealing for proof to a fan-
No. 518] REGENERATION 1038
tastic ancestral condition. But quite apart from that,
the looseness of his argumentation is further increased
by the circumstance that anatomists are by no means
certain that the pineal body is an eye, and judging by the
structure of its lens it may also be a heat-perceiving
organ, as some indeed have suggested.
Thus far I have been considering what might properly
be called the preliminary steps leading to the hypothesis,
that the end result of regeneration differing from the
usual result of ontogenetic development lends the key to
a solution of obscure morphologic problems. This sug-
gestion or idea is at the bottom of Davydoff’s entire
work; it persistently crops up here and there throughout
the monograph. In short, it is the soul of that work.
From what has been said in the foregoing it ought to
be clear that if the hypothesis of the repetition of ontog-
eny in regeneration, and also that of the atavistie na-
ture of the deviations from the normal condition, are not
false assumptions, they are at least deserving the verdict
‘“*not proven.’’ Since in no known system of logic does
the truth issue from propositions, either wholly untrue
or else of such uncertain veracity as to leave free choice
to intellectual likes and dislikes, it would seem that
Davydoff was laboring largely under a mistaken prin-
ciple.
I am, however, ready to go to the extent of granting,
just for the sake of further argument, that the first two
propositions are demonstrably true, and that conse-
quently Davydoff’s idea of using regenerated peculiari-
ties for the purpose of solving obscure problems of
phylogenetic importance is, humanly speaking, beyond
objection. A moment’s consideration will not fail to con-
vince us that even though truth may be a quality of
Davydoff’s principle, its function could be either of
purely negative value or even of no value.
The literature on regeneration abounds in instances
of departures from the normal which appear either
sporadically or even regularly in the course of regenera-
104 THE AMERICAN NATURALIST [VoL. XLIV
tion of organs. Earthworms regenerate heteromorphic
tails and planarians regenerate heteromorphic heads.
Do these peculiarities signify any reversion to a more
primitive condition? Double and multiple structures
likewise frequently appear in the regeneration of organs,
as, for instance, the regeneration of double heads in
planarians or in Luwmbriculus. Do these abnormalities
bring any message about the normal state of things in the
remote past? Likewise, as Davydoff informs us, En-
teropneusta may regenerate double pericardial sacs or
double notochords. What is the morphological and his-
torical significance of these unusual formations? Going
through a list of such irregularities and departures from `
the normal, one may doubtless find all gradations from
the obvious freaks of nature down to such as may claim
a respectable ‘‘atavistic’’ distinction. But the question
is, what will guide us in discriminating between these
various departures, for after all every departure in re-
generation originates under the special conditions of an
amputation. The manner in which Davydoff overcomes
the difficulty of this question is both characteristic and
interesting, and we shall return to it soon. It should be
pointed out, however, first that no existing theory of
phylogenetic significance can be invalidated to the slight-
est degree by the failure to regenerate on the part of
such structural peculiarities or characteristics as may be
postulated by the theory as primitive or ancestral. On
the other hand, any sporadie growth in the process of
regeneration, if by play of chance it should happen to
coincide with a theoretical anticipation, would become an
additional support to the theory. In other words, in any
disputed theoretical problem of animal phylogeny the
evidence derived from the study of regeneration must
by the limitations of its own nature be always of the
affirmative kind. It is the better part of wisdom to be-
lieve much too little rather than a little too much, and on
this account we should hesitate to rely upon evidence
from regeneration.
No. 518] REGENERATION 105
But to return to the original question as to what should
guide us in deciding where, in regeneration, mere ab-
normalities or monstrosities end and where ‘‘palin-
genesis’’ and ‘‘atavisms’’ begin. Let us see how Davy-
doff proceeds with this question. He records among
others two cases where occasionally double structures re-
generate instead of the normally single structure, viz.,
the doubling of the pericardial sac and of the notochord.
The meaning of these parallel facts is equally puzzling
to us and, broadly considered, the two facts are to all in-
tents and purposes of the same importance. But Davy-
doff rummages through the volumes in the library for
light upon the significance of these extraordinary in-
stances. There he discovers that the much-esteemed,
and certainly authoritative writer of the ‘‘Beitrige zur
einer Trophoceelthorie’’ in speaking of the ‘‘ Herzblase’’
of Balanoglossus suggests in parentheses and under the
auspices of a question mark that the ‘‘Herzblase’’ may
have been primitively a double structure. This sugges-
tion is expressed just in two words—(urspriinglich
paarige?). Evidently Davydoff had not succeeded in
finding in the literature: another similar hypothesis that
the notochord, too, may have been primitively a double
structure. I judge so, because without offering any
further reasons, he dismisses the puzzle of a double
notochord by proclaiming it an abnormality, while honor-
ing the double pericardial sac with the distinction of
- atavism.
Thus does Davydoff solve the question, and whatever
merits or demerits his answer may have from the point
of view of common sense, one thing is certain: that there
is no direct, immediate way of deciding the question.
We must fall back upon a theory, a hypothesis, a sug-
gestion, even a mere guess, in distinguishing between
what is abnormal and what is ancestral in regenerated
structures. In a word, it is the theory which, in accord-
ance with Davydoff’s solution of the question, must give
value to the observed facts.
106 THE AMERICAN NATURALIST [Vou. XLIV
This principle is diametrically opposite to the principle
laid down in the introduction to this paper, that the na-
ture of the relation between facts and theories is such
that the facts can not be valued by their compliance with
theories. We need theories for inspiration and enlight-
enment, we need facts to build upon; but to discriminate —
between facts in favor of any mental conception is to
place oneself upon the inclined plane of immoderate
speculation.
To sum up: While the evidence shows that as a rule
organs originate from similar germ-layers, both in on-
togeny and in regeneration, there are also some striking
exceptions to the rule. The hypothesis, that the method
of regeneration is causally influenced by the course of
ontogeny, is, therefore, quite unnecessary as a corollary.
With the elimination of this hypothesis the conception
of the atavistic nature of regenerated peculiarities, i. e.,
the conception of a repetition in. regeneration of phylo-
genetic processes, loses its chief logical support. This
last theory, however, is also objectionable (1) because of
its inherent inconsistency, (2) because it depends upon
more or less problematic assumptions.
With both hypotheses, those of the repetition in re-
generation of ontogenetic and of phylogenetic processes,
now discredited, it would be venturesome to take sides in
unsettled questions of animal morphology upon the
ground of evidence deduced from a study of regeneration.
But even if the hypothesis were correct, to accept it as a
working principle is to put oneself deliberately into the
logician’s vicious cirecle—proving theories with facts
approved of by the theories.
BIBLIOGRAPHY
Abel, M. Regenerationsvorgiinge bei den limikolen Oligochaeten. Zeitschr.
f. wissenschaftl. Zool., Vol. 73, pp. 1-74, 1902.
Barfurth, D. Die experimentelle Regeneration iiberschiissiger Gliedmassen-
theile (Polydactylie) bei den Amphibien. Arch. f. Entwicklungsm.,
Vol. 1, pp. 91-116, 1894.
No. 518] REGENERATION 107
Boulenger, G. A. (a) On the Scaling of the Reproduced Tail in Lizards.
roc. Zool. Soc. London, p. 351, 1888. (b) On an Iguana with Repro-
duced Tail. Proc. Zool. Soc. Lakai; p. 466, 1891.
Braem, F. von. Was ist ein Keimblatt? Biol. Centralbl., Vol. 15, pp. 427-
443; 466-476; 491-506; 1905.
Hazen, H. E: Romavecetion of the (sophagus in the Anemone Sagartia
lucie. Arch. f. Entw., Vol. 14, pp. 592-599, 1902.
Hepke, Paul. Ueber ‘lets und organo-genetische Vorgiinge bei den Regen-
agora eye der Naiden. Zeitschr. f. wissenschaftl. Zool., Vol. 63,
pp. 1897.
cae k . H. On Certain Characters of Reproduced Appendages in
Arthropoda, particularly in the Blattide. Proc. Zool. Soc. London,
pp. 924-958, 1898
Davydoff, K. N. Observations on the Process of Regeneration in Enterop-
neusta. Mem. de Pann Impériale des Sciences de St.-Pétersbourg,
Vol. 22, No. 10, pp. 1-120, 1908 (Russian).
Morgan, T. H. Regeneration, 1901.
Reed, M. The Regeneration of the First Leg of the Cray-fish. Arch. f.
ee Vol. 18, pp. 307-317, 1904.
mes tenes . G. On the Skeleton of Regenerated Limbs of the Midwife-
oad aii obstetricans). Proc. Zool. Soc. London, pp. 101-106, 1897.
errs si W. Ueber den Atavistischen Charakter der ane regenera-
tion bei Amphibien. Anat. Anz., Vol. 21, No. 2, pp. 4
Schultze, L. S. Die Regeneration des Ganglions von Ciona maou: L.
und über das Verhiiltniss der Regeneration und Knospung zur Keim-
blatterlehre. Jenaische Zeitschr. f. Naturwiss., Vol. 33, pp. 263-344,
1900.
Schultz, E. Ueber das Verhiiltniss der Regeneration zur Embryonalentwick-
lung und Knospung. Biol. Centralbl., Vol. 22, pp. 360-368, 1902
Wagner, F. von. Einige Bemerkungen über das Verhiltniss von Ontogenie
und Regeneration. Biol. Centralbl., Vol. 13, pp. 287-296, 1893.
Wolff, G. Entwickelungsphysiologische studien I. Die Regeneration des
Urodelaatenss: Arch. f. Entwicklungsm., Vol. 1, pp. 380-390, 1895.
GENETICAL STUDIES ON ŒNOTHERA. I
NOTES oN THE BEHAVIOR OF CERTAIN HYBRIDS OF
(ENOTHERA IN THE First GENERATION
BRADLEY MOORE DAVIS
Tue following account is a report on the behavior in
the first generation of the following sets of hybrids of
(nothera grown in the Harvard botanic garden in the
summer of 1909: (1) gigas X Lamarckiana, (2) muri-
cata X gigas, (3) muricata X grandiflora, (4) biennis X
grandiflora, (5) grandiflora X biennis. The hybrids were
not grown on an extensive scale, but represented rather a
selection from the seedlings of the best plants in order to
obtain for a special purpose the most vigorous crosses
possible. The cross pollination was made in the writer’s
garden at Woods Hole in 1908, and the hybrids started
in the hothouses at Cambridge early in January, 1909.
Large rosettes were in most cases developed by the last
of May, when the selected plants were set out in the
botanic garden. All of the hybrids matured during the
summer except a few plants of the cross gigas X La-
marckiana, which persisted in the rosette condition.
1. gigas X Lamarckiana. The parent forms of this
cross were grown from seeds of De Vries, Lamarckiana
having 14 chromosomes and gigas showing from a pre-
liminary examination apparently twice this number.
Twelve rosettes were planted exhibiting wide variation
in the forms of the leaves, eight being similar to Lamarck-
iana and four similar to gigas. Two of the Lamarckiana-
like rosettes and three of the gigas-like remained as
rosettes throughout the summer, the former at the end of
the summer being 3.5-3.7 dm. broad with leaves narrower
than those of gigas, lanceolate and narrowly spatulate
in form, the gigas-like being 4.5-5 dm. broad and indis-
tinguishable from those of gigas.
Seven of the rosettes developed into mature lant
which were similar to one another, 1-1.1 m. high with
o 108-
No.518] GENETICAL STUDIES ON ŒNOTHERA 109
the characteristic habit and foliage of gigas; the large
flowers and stout buds, ovaries and seed capsules, were
also gigas-like. Some eighty attempts to obtain seed by
guarded self pollination gave complete failures, which
were the more interesting because ovaries presumably
pollinated from neighboring Œnotheras by the numerous
insect visitors matured large fruits and quantities of
seeds; the failure to self-pollinate was thus apparently
not due to abnormalities of the ovules. De Vries! re-
ports that he has obtained fertile seed of this hybrid as
well as of the reciprocal cross. There was a large pro-
portion of abortive pollen, perhaps 80-90 per cent., but
the remaining grains, as regards outward appearances,
seemed normal. These latter consisted of a mixture of
3-lobed and 4-lobed grains in various proportions for dif-
ferent plants, the 3-lobed preponderating. Four-lobed
pollen grains, as reported by Miss Lutz,? are character-
istic of gigas.
2. muricata X gigas. The gigas parent furnishing
the pollen of this cross was the same as in the preceding
culture; the muricata parent was a wild plant from
Woods Hole transplanted as a rosette to the garden of
1908. Hybrids of these were among the most interesting
of the cultures of 1909. The well-developed rosettes
were strikingly intermediate between those of the two
parents, but fell clearly into two groups. Of the twelve
plants in the culture six rosettes had leaves muricata-like
in form but of a larger size than is typical of this species,
and six rosettes had leaves broader than the above and
conspicuously crinkled like the gigas parent.
The mature plants exhibited a similar difference; the
first six had a habit and foliage that were muricata-like,
the leaves, however, being longer and 2-3 times as broad;
the other six plants presented a much stockier gigas-like
habit with a stouter main stem and with leaves, which on
the lower portion of the stem were strongly crinkled as in
gigas. The flowers, inflorescences and capsules were
‘De Vries, H. (’08b), ‘‘Bastarde von CEnothera gigas,’’ Ber. deut. bot.
Gesell., XXVIa, 754, 1908.
2 Lutz, Anne M., ‘‘Notes on the First Generation Hybrid of Gnothera
lata X 0. gigas,”? Science, XXIX, 263, 1909.
110 THE AMERICAN NATURALIST [Vou. XLIV
quite similar in both groups of hybrids and presented
forms and measurements intermediate between the two
parents. The flowers, however, were decidedly smaller
than the mean, and resembled those of the female muricata
parent although about twice as large. The hybrids then
as regards habit and foliage fell in about equal propor-
tions into two groups, with greater resemblances to one
or the other of the two parents. They presented an ad-
mirable illustration of the type of crosses called by De
Vries? ‘‘twin hybrids’’, and reported for crosses between
the Onagra group and Lamarckiana, or one of its deriva-
tives, when these latter furnish the pollen.
These hybrids when self-pollinated set an abundance
of seed which germinated readily, in sharp contrast to the
experience recorded above for the hybrids of gigas X
Lamarckiana. De Vries (’08b, p. 761). reports that
hybrids of this cross as well as of the reciprocal have
proved entirely sterile in his cultures. The fertility of
my cross is especially interesting since we are dealing
with a hybrid one of whose parents (gigas) has twice as
many chromosomes as the other. A large proportion of
the pollen grains, 75 per cent. or more, was abortive; the
normal grains were almost wholly of the 3-lobed foni
(as in muricata), 4-lobed examples being uncommon.
3. muricata X grandiflora. There were two cultures
of these hybrids based on two muricata parents from
Woods Hole, pollinated, however, from the same grandi-
flora plant which was used in the crosses of biennis
and grandiflora, a plant which is described somewhat
fully below. The cultures comprised twenty-nine plants
which did not pass through conspicuous rosette stages in
the hot houses, but quickly developed the main stems,
which were 1-2 dm. high when the plants were set out in
the garden. Somewhat later these young plantes with
main stems 4-6 dm. high presented clearly a foliage inter-
mediate between the parent types in form, color and tex-
ture. Thus the leaves were narrower, thicker, and a
3? De Vri H. (’07), ‘‘On Twin Hybrids,’’ Bot. Gaz., XLIV., 401, 1907.
(08a), ‘*Ueber die Zwillingsbastarde von @Œnothera mansn i Ber. deut.
bot. Gesell., XXVIa, 667, 1908.
No.518] GENETICAL STUDIES ON GENOTHERA 111
darker green than those of grandiflora, but broader,
thinner, and a lighter green than those of muricata.
On reaching maturity four plants exhibited flowers al-
most as large as those of grandiflora, and a habit and
foliage more like this parent than was shown by the other
hybrids; these four plants were, however, only 1.2 m.
high while neighboring grandifloras were 1.5 m. high and
much more extensively branched. The remaining hy-
brids, twenty-five in number, were strikingly muricata-
like in habit and foliage except that the leaves were
broader than those of that parent and the flowers more
than twice as large, in size somewhat midway between
the small flowers of muricata and the very large flowers
of grandiflora. These hybrids then, as in the case of the
muricata X gigas, fell into two groups (twin hybrids)
with marked resemblances to one or the other of the
parents, but with all structural characters blended. The
proportion of four grandiflora-like to twenty-five muri-
cata-like forms probably does not represent the normal
ratio between the plants of these two groups which would
be expected to appear in about equal numbers.
There was certainly no evidence from the cultures of
any tendency on the part of the hybrids to resemble
markedly the male parents (patroclinous) as was re-
ported by De Vries (’07) to be the rule among Œnothera
hybrids of the Onagra group. On the contrary five sixths
of the hybrids were strikingly similar to the female
parent, although, as stated above, it is not likely that
these proportions represent normal ratios.
4. biennis X grandiflora. The parents of this cross
were carefully selected with an end in view. The biennis
plant was found wild at Woods Hole and transferred to
the garden of 1908; it was chosen as representative of
the broader-leaved types of this variable species with,
however, only medium-sized flowers. This strain of
biennis has proved constant in the cultures of 1909, pre-
senting the characteristic biennis habit of a main stem
about 1 m. high and long side branches arising from near
the base of the plant. The grandiflora parent was one
of nine plants grown from seed collected by S. M. Tracy
112 THE AMERICAN NATURALIST [VoL. XLIV
at Dixie Landing near Tensaw, Alabama, a well-known
locality for the species. It was selected because of the
breadth of the leaves, which in this species present a
wide range of variation from lanceolate to broadly
elliptical, and for the reddish coloration of the sepals
which in other forms of grandiflora may be a clear green.
This plant in the Woods Hole garden grew to be 2.1 m.
high and presented a habit characterized by a strong
main stem and long side branches rising from near its
base. .
Eight plants of this cross were brought to maturity in
the garden of 1909 and exhibited a wide range of form.
Seven of them were markedly grandiflora-like in habit
and foliage, but with shorter main stems, 1.1-1.5 m. high;
the flowers were somewhat smaller than those of the
grandiflora parent. It is not safe, however, in a rela-
tively small culture to draw conclusions from this large
proportion of the hybrids resembling the male parent
(patroclinous), especially since in the reciprocal cross
described below approximately half of the plants re-
sembled the female parent.
One of the hybrids (9ba) proved interesting for its
resemblance in certain respects to Gnothera Lamarck-
iana. This plant was 1.3 m. high with a strong main
stem and the side branches, as in Lamarckiana, well dis-
tributed along the axis, in contrast to the origin of the
chief side branches from near the base of the plant which
is generally characteristic of both biennis and grandiflora.
The flowers were intermediate in their measurements
between the biennis and grandiflora parents and so similar
to those of Lamarckiana as to be practically indistin-
guishable in the features that would enter into a taxo-
nomic description of the flowers of the latter. The dif-
ferences (such as a slightly greater length of the stigma
lobes) were probably no greater than would be found
among the flowers of any culture of Lamarckiana which
included a fair representation of the range of variation
presented by this form.
The important differences between this hybrid plant
and Lamarckiana were concerned then with the foliage,
No.518] GENETICAL STUDIES ON G@NOTHERA 113
‘but were very marked. The leaves in general were bien-
nis-like in form, but slightly larger in théir measurements.
Those on the lower portion of the main stem, which in
Lamarckiana are 20 em. or more in length and much
crinkled, were in the hybrid only 11 em. long and exhib-
ited only a very slightly crinkled surface. The leaves
along the upper portions of the branches and the bracts
of the inflorescences were on the contrary larger than
those of Lamarckiana and the inflorescence was, therefore,
conspicuously larger leaved. The rosette condition of
this plant, as grown in the hot house, was too transitory
to give satisfactory conclusions as to what its character-
istics would have been if given the opportunity of a more
prolonged development.
This hybrid set seed abundantly when the flowers were
self-pollinated. Less than 50 per cent. of the pollen was
abortive. The normal grains were almost entirely 3-
lobed like the pollen of the parents, but oceasional 4-
lobed grains were present.
5. grandiflora X biennis. The parents of this recipro-
cal cross were the same individual plants employed in the
preceding (4). The culture consisted of twenty plants
which fell clearly into two groups (twin hybrids) with
greater resemblances to one or the other of the parent
forms.
Nine of the hybrids were grandiflora-like in foliage
and habit, the leaves being lanceolate in form, longer,
narrower and more pointed than those of biennis, and the
plants taller (1.3 m.), presenting also the numerous
heavily flowered side shoots characteristic of grandiflora.
The flowers were intermediate in form and measurements
between those of the parent types, and essentially similar
to the flowers of Lamarckiana. Five of these hybrids
developed large rosettes with leaves similar in form to
those of biennis but more pointed; the leaves of four of
the rosettes exhibited marked crinkles like those of
Lamarckiana.
The remainder of the hybrids of this cross resembled
the biennis parent in foliage and habit. The leaves were
broadly elliptical or ovate in form, shorter than those of
114 THE AMERICAN NATURALIST [Vowu. XLIV
the grandiflora-like hybrids, and thicker in texture. The
plants were shorter (.8-1.1 m. high) and the habit
biennis-like in being sparingly branched, the side
branches arising from near the base of the plant and
being almost as long as the main stem. The flowers were
intermediate between the parent types, but exhibited a
somewhat greater range of measurements than those of
the grandiflora-like crosses.
In three of these biennis-like hybrids (9ba, 9bb and
9bc) the flowers and inflorescences presented a structure
so similar to that of Lamarckiana that they matched in
all essentials the branches on certain Lamarckiana plants
in the garden. The differences in the form of the bracts
and parts of the flower were of the sort that can be ob-
served in any reasonably large culture of Lamarckiana.
There were, however, striking differences between
these three hybrid plants and Lamarckiana with respect
to their foliage and habit of growth. The leaves on the
lower portion of the stem were only 9-11 em. long, about
half the length of leaves similarly placed on Lamarck-
iana, and there were only slight traces of the crinkles
so characteristic of Lamarckiana. The biennis-like habit
of putting out long side branches from near the base of
the plant was also very different from the usual habit of
Lamarckiana in which the prominent side branches are
more regularly distributed along the main stem.
These plants formed such transient rosettes in the hot-
house that no conclusions could be drawn as to what
would be their characters if allowed to develop more
slowly. Seed was produced in abundance by self-polli-
nated flowers. Less than 50 per cent. of the pollen was
abortive, the normal pollen, except for an occasional 4-
lobed grain, was entirely 3-lobed.
GENERAL CONSIDERATIONS
While it is impossible to draw broad conclusions from
these hybrids, which have as yet been observed only in
the F, generation, a number of interesting points may be
noted: .
1. The characters of the parents, as presented in each
No.518] GENETICAL STUDIES ON GNOTHERA 115
cross, were so blended that as regards the measurements
of parts, habit, texture of foliage, ete., the average for
each set of hybrids would probably present a fair mean
between the two parents concerned. There was, how-
ever, a wide variation in the resemblance of the hybrids
to one or the other of the parents.
2. No character of either parent was discovered which
appeared as dominant in these hybrids of the F, genera-
tion, after the manner which has been described for cer-
tain forms (e. g., Pisum) that illustrate most conspieu-
ously Mendelian dominance in the first generation.
3. Some of the hybrids of each cross presented a greater
resemblance to one parent and some to the other, and the
forms could therefore be arranged in two groups (twin
hybrids) in one of which the maternal characters were
most evident and in the other the paternal. There was
no clear evidence that the hybrids of these cultures car-
ried in marked preponderance the paternal characters
(patroclinous), or on the other hand that maternal char-
acters were more prominent. The range of variation
among the hybrids was too great to permit of such con-
clusions.
It becomes a matter of interest to determine how
plastic these hybrids will prove to be in later generations,
and whether or not they will exhibit variations that may
be fixed and accentuated by artificial selection. This line
of enquiry will be especially pertinent to the behavior
of those hybrid plants of biennis and grandiflora which
in this F, generation presented Lamarckiana-like flowers
and inflorescences, although differing markedly from
Lamarckiana in habit and foliage.
I am greatly indebted to the Harvard botanic garden
for the facilities placed at my disposal for this work.
CAMBRIDGE, MASS..
December. 1909.
SHORTER ARTICLES AND DISCUSSION
THE MENDELIAN VIEW OF MELANIN FORMATION
APPARENTLY there is no danger that the biological world will
suffer permanent paralysis as the result of general acquiescence
in hypotheses which have recently gained wide acceptance but
for which fundamental proof seems not to be forthcoming.
Especially is this the case when biologists whose special fields
of work give them only an incidental interest in Mendelian and
de Vriesian affairs will take the trouble to attach their batteries
to the wires leading into the Mendelian field in order to counter-
act the paralyzing effect of what they regard as intellectual
poison. I am a firm believer in the value of scientific trespass.
Very frequently a group of scientists become moribund because
they have no one to criticise them. An outsider who finds that
his own work touches that of such a group may render real
service by pointing out relations which those immediately con-
cerned have overlooked and may thus cause readjustments of
theory and hypothesis that are frequently much needed.
An excellent case of this kind is found in Riddle’s interesting:
article in the Biological Bulletin for May, 1909.1 One can
hardly read this article without suspecting that Riddle is pur-
posely somewhat extreme in his attack on the current interpre-
tations of Mendelian phenomena in order to get a response from
those who are responsible for these interpretations. It appears
to the writer that Riddle attacks very successfully the de
Vriesian interpretation of these phenomena. Unfortunately,
however, he utterly confuses Mendelian facts with de Vriesian
and Weismannian theories—hypotheses, rather, and attempts to
throw both facts and hypotheses out of court. Riddle is not
entirely to blame in this matter, however, for the de Vriesians
generally have made the same mistake. If Riddle succeeds in
arousing Mendelianists to a realization of the fact that the facts
of Mendelian inheritance are not dependent on de Vriesian
hypotheses he will have rendered a distinct service to biology.
+**Our Knowledge of Melanin Color Formation and Its Bearing on the
Mendelian -r of Heredity,’’ Oscar Riddle. Biol. Bul., May, 1909,
pp. 316-351
116
No.518] SHORTER ARTICLES AND DISCUSSION 117
Mr. Riddle must not forget that we have a long list of incon-
trovertible facts that are not in disagreement with the facts of
melanin production cited by him, and which are not dependent
on any theory involving discontinuous variation, but which may
be interpreted in such a way as to take cognizance of the ascer-
tained facts of physiological chemistry. Riddle throws all
‘‘factor’’ hypotheses overboard, apparently under the impres-
sion that they all depend on the Weismannian doctrine of deter-
minants. Fortunately, such is not the case. These hereditary
factors are established facts, while the Weismannian conception
of them is, in the writer’s view, probably wholly wrong.
Riddle points out that the chromogens in animals are tyrosin
and related aromatic compounds. Tyrosinase, an oxidizing
enzyme, converts tyrosin into melanins. Fuerth and Schneider
concluded that ‘‘tyrosinase-like ferments are widely distributed
in the animal organism and probably always appear wherever
and whenever a physiological or pathological formation of
melanin occurs.’ Gessard showed that the presence of acids,
alkalis and salts has a marked effect on the colors produced
by the action of tyrosinase on tyrosin. Bertrand determined
the type of substance, of which there are many representatives,
which tyrosinase can oxidize to melanins. In the oxidizing
process each of these substances are converted step by step
through a series of colors before reaching the final stage. They
vary somewhat as to initial and final colors, the early stages
being lighter than the later. The series of colors usually runs
from yellow to orange, proceeding onward to brown or black.
Any benzine nucleus with a hydroxyl attached can be converted
to a melanin by tyrosinase. Some substances have red or
mahogany as the final stage reached in the oxidation process.
Riddle further points out that the facts of the pathological
development of melanins show the dependence of tyrosin oxida-
tion upon somatie conditions which may be of temporary, in-
termittent, or reversible character, but he assumes, without
sufficient basis, that these facts preclude the possibility of ac-
counting for observed phenomena of color inheritance on a basis
of specific transmission and segregation in the germ cells. He
seems to think that any kind of segregation in the germ cells
necessarily implies pangenes, such as those proposed by de Vries,
or determinants, such as those proposed by Weismann. It is
easily shown that this is not the case. The facts of segregation
118 THE AMERICAN NATURALIST [VoL. XLIV
are not at all inconsistent with the idea that melanin formation
is in itself a generalized function of the cell. Cytological in-
vestigations during the past two or three decades lend support
to the hypothesis that the cell is composed of a number of more
or less definite organisms. Now the production of black pig-
ment, for instance, may be a process in which-every organ of the
cell plays a part. Riddle has shown that the particular color
of an organism, when this color is melanie in character, is due
to the fact that the oxidation process stops at a more or less
definite point. We may imagine that the relative quantity of
tyrosin and tyrosinase present in the cell has something to do
with the point at which the process terminates under normal
conditions. Now if a single cell organ should, because of some
change in its nature, fail to produce its usual measure of one
of these necessary substances, we may easily imagine that the
point at which the oxidation process would stop would be
changed accordingly. Now if the cell organ which is respon-
sible for this difference happens to be a chromosome, and if
- chromosomes behave in the reduction division as a great many
cytologists believe they do, then we at once get the phenomenon
of Mendelian segregation independent of any idea of unit
characters at all. This idea will be further developed in another
paper by the present writer. |
Riddle continually draws conclusions that do not seem to be
justified by the facts he states. For instance, he states that
melanin formations, under certain pathological conditions, ‘‘in-
dicate that for the building of any melanin at all the actual
conditions of the organism or the organ have a rôle to play that
is quite out of keeping with any ‘onee-for-all determinance’ by
the shuffling of color factors through the germs.” This is not a
necessary conclusion unless we think of color factors as definite
organs in the cell. I have just pointed out that what we have
been calling factors may really be only differences in function
of cell organs. There is no doubt at all that, for the develop-
ment of almost any peculiarity or character, local conditions
in the organism are important factors, but they are not the only
factors. There must have come through the germ cell certain
tendencies before these characters could develop at all. The
horns of cattle are a good illustration of this point. These
organs develop only at certain points of the organism, but the
tendency to develop them when the proper conditions are given
No.518] SHORTER ARTICLES AND DISCUSSION 119
in the organism is unquestionably a matter of inheritance, nor
can there be any question that there is a Mendelian segregation
with reference to this tendency. This does not mean, however,
that there is a bullet somewhere in the germ plasm which is
wholly responsible for the development of horns. I imagine
that the development of horn tissue is a process in which prob-
ably all of the organs of the cell participate; but if there is
one organ which has become so changed in its functions that
it can no longer take its usual and necessary part in the de-
velopment of these organs, and if this organ is a chromosome,
then we necessarily get the phenomenon of Mendelian segregation
in inheritance with reference to this character.
Riddle points out a good many facts that it is well for Men-
-delianists to keep in mind in formulating hypotheses to account
for the facts they discover. One of the most interesting of
these is the finding by Spiegler that the hair of white horses and
the wool of white sheep contain a white melanin. Some investi-
gations indicate that these white melanins represent a more
advanced stage of oxidation than do black melanins. White
of this character we should therefore expect to be dominant, in
the Mendelian sense. Riddle suggests that in certain white
birds, and I presume the same would apply to albinos generally,
the oxidation is not carried far enough to produce color. In
these cases we should expect white to be recessive, in the
Mendelian sense.
That melanin production is at least frequently the result of a
long series of reactions is strongly indicated by Fornier’s ex-
periments on tadpoles. By giving varying amounts of nutri-
ment he was able to produce a series of colors in these animals
ranging from white through gray, and finally from yellow to
black. Apparently these results were due to the fact that in
individuals insufficiently nourished the oxidation process ended
at different points in the series of possible stages.
The writer has observed a similar phenomenon in the case
of cow-peas. In varieties of these plants having highly colored
seeds it is a frequent occurrence to find imperfectly developed
seeds of lower color than perfectly developed ones. For instance,
the black-seeded varieties occasionally imperfect seeds are found
which are light brown, due, presumably, to the fact that the
oxidation process in these seeds did not reach the stage normally
reached in perfect seeds. It may be further noted that in cow-
120 THE AMERICAN NATURALIST [Vou.XLIV
peas melanin production seems to occur only in the later stages
of development.
From a few facts like those above stated Riddle makes the
sweeping conclusion that ‘‘in an animal that produces melanin
color there exists all the machinery necessary to produce a
series or scale of these colors. What is actually produced is,
in several demonstrated instances, dependent on the physiolog-
ical state of the organism.’’ It does not necessarily follow that
this is true in all organisms, or even in all animals, though it
must be admitted that such may be the case. There is a good
deal of evidence that in some organisms the oxidation processes
do not lead through a series of colors, such as Fornier found in
tadpoles, but that when color begins to appear at all it is of a
definite character and that we have variation only in the amount
of that color present. It seems quite probable that in some
organisms the mechanism present is limited to the production
of a single color character, yet this is a matter for further in-
vestigation.
Even if there is only one process of oxidation and the series
of reactions results in a graduated series of color pigments this
does not necessarily imply that a tendency to a certain color is
not purely hereditary and that it could not undergo the phe-
nomena of segregation. The normal stage of oxidation reached
in an organism may be an intermediate one, as in red cattle.
If a single cell organ is responsible for the oxidation process
stopping at this stage, and if that cell organ behaves as chromo-
somes appear to do at least in some organisms, then we would
necessarily have the phenomenon of Mendelian segregation.
Riddle seems to labor under the impression that in order to
explain the so-called Mendelian factors it is necessary to assume
an indefinite number of specific enzymes or chromogens. I
think I have already said enough to point out that this is not the
fact. There is much evidence, however, that in the color of
animals we do have at least three specific enzymes or chrom-
ogens, for we find three kinds of color material deposited in the
same parts of the organism. Furthermore, the tendency to
produce each of these three types of pigments has been demon-
strated to be separately heritable.
Riddle points out the very interesting fact that Miss Durham?
2 Proceedings Royal Society, Vol. 74.
No.518] SHORTER ARTICLES AND DISCUSSION 121
investigated the enzymes in the skin of black, chocolate, yellow.
and albino mice, and reported finding enzymes for black, choco-
late, and yellow. Riddle criticizes Miss Durham’s conclusions.
for no other apparent reason than that they apparently oppose
his views. In albinos Miss Durham was not able to decide
definitely concerning the presence of enzymes but was of the
opinion that the enzymes were not present. Riddle’s suggestion
that yellow is a blend between albino and black would be quite
interesting if we did not know that it is not true. Castle has
recently shown that the tendency to produce yellow pigment,
in rabbits at least, is a separately heritable tendency. On the
other hand, we can agree with Riddle’s statement that the
‘‘data warrant the definite statement that yellow mice are forms.
with the power of oxidizing tyrosin compounds, to an inter-
mediate point.’
If it were not for the well-established facts of segregation in
the inheritance of color, Riddle’s statement that ‘‘in gametic
unions we deal not at all with factor particles but merely mix
and amalgamate to various degrees powers of tyrosin oxidation
and conditions supplied by the differentiations of tissues and
organs, together with environmental conditions external and
internal, supply whatever else is concerned in color produc-
tion.” It is really to be regretted that Riddle does not know
more of the facts of color inheritance, for his incisive remarks
indicate that if he knew these facts and took proper cognizance
of them he would be highly useful to Mendelianists by way of
developing an explanation of Mendelian phenomena more in
keeping with the facts of physiological chemistry.
His criticism of Castle’s work on rabbits is entirely unfounded.
He assumes that the factors found by Castle can not exist apart
from pangenes of the de Vriesian type, each of which is wholly
responsible for the development of a Mendelian character.
Castle’s work shows that he has no such idea. He merely worked
out the facts of color inheritance in rabbits, and, except for a
brief reference in his closing paragraph about a possible mechan-
ism for their explanation, gives no indication that he has any
theory to explain them. He certainly does not commit himself
to the de Vriesian theory. Castle has shown us that there are
three kinds of pigments in the hairs of rabbits whether they
should be there or not, and that the tendency, under normai
conditions, to produce these pigments is hereditary ; furthermore..
122 THE AMERICAN NATURALIST [Vou. XLIV
that these tendencies are separately and independently trans-
mitted. The fact is that there is nothing in the scheme of color
factors presented by Castle inconsistent with the facts of color
production presented by Riddle, unless it be that they call for
two or three more or less distinct oxidizing processes instead of
only one. Even the view that there is only a single process
involved is not excluded if we can find a mechanism operative
in development that stops the oxidation partly at one stage and
partly at another.
I agree with Riddle that the placing of the ‘‘uniformity-
spotted,’’ ete., factors on the part of Castle in the germs of
rabbits as alternative factors is a virtual surrender of the whole
theory of discontinuous variation. According to my view, this
theory has never had any sound basis except as a result of
irregularities in the behavior of chromosomes, and Mendelian
facts are not dependent on any such theory or in any way re-
lated to it, as the writer has repeatedly pointed out. Professor
S. J. Holmes has also pointed out the fallacy in the assumption
that Mendelian phenomena necessarily prove the theory of dis-
continuous variation.
That there may be more than one oxidation process concerned
in the development of color in organisms is shown by a number
of facts cited by Riddle. He gives a table of oxidation processes
in which the end reactions result in various colors. He further
cites the fact that lipochromes and guanin may possibly be the
source of color in certain amphibia.
The author attempts to explain the variability in the second
generation of hybrids as a result of unstable equilibrium of
oxidation processes in the first generation. According to his
view each of the gametes represents a stable condition. The
first generation may be a compromise between the stable condi-
tions found in the two gametes. In the second generation there is
a tendency to revert to one or both of the stable points. This
view is hardly in keeping with observed phenomena. The
regularity with which certain types appear and their subsequent
behavior with reference to the transmission of hereditary tend-
encies indicate, apparently beyond question, that there is some
such definite segregation as would result from the assumption
that the chromosomes play an important part in the general
processes of cell metabolism.
Riddle shows his lack of knowledge of Mendelian principles
No.518] SHORTER ARTICLES AND DISCUSSION 123
and facts in his reference to the real contributions which Mendel
has made. ‘‘The really important Mendelian contribution be-
ing that certain definite characters (such as have according to
my belief, rather general processes as a basis) of different races
may be combined to form new fixed races’’ (with which we all
agree). ‘The establishment of this last fact has been most `
commonly considered by Mendelians on the one hand a conse-
quence of the laws of dominance (!) and segregation, and on the
other hand as a strong argument for a ‘representative particle’
basis for these two sets of phenomena.’’ There are some Men-
delians who really do not believe there is any law of dominance,
and there are many more Mendelians who do not believe in a
representative particle theory at all. Here, as elsewhere
throughout his paper, Riddle confuses Mendelism with de
Vriesianism and Weismannism. The following quotation ap-
plies only to de Vriesians and Weismannians, not to Mendelians:
‘With an eye seeing only particles and a speech only symbol-
izing them there is no such a thing as the study of a process
possible.’’ Castle in his work on rabbits has no such particles
in his mind’s eye; his terminology does not imply them; he
merely describes the facts of color inheritance.
While in this review of Riddle’s most interesting paper the
writer has been compelled to appear to combat him at almost
every point, he is quite in sympathy with Riddle’s point of view.
The thing he has tried to combat is Riddle’s confusion of Men-
delian facts with de Vriesian hypotheses. The writer hopes in
the near future to be able to present a theory of Mendelian
inheritance which is independent of the idea of unit characters
and wholly independent of the idea of discontinuous variation.
W. J. SPILLMAN.
NOTES AND LITERATURE
Seton’s ‘‘Life Histories of Northern Animals.’’*—Mr. Seton is
widely known to the general public as a lecturer on wild animals
and as the author of several popular works on the same subject,
of which his ‘‘ Wild Animals I have Known”? is the type, wherein
the life of the species is personified in the history of an individ-
ual representative, as in ‘‘Lobo, the King of Currumpaw,’’
‘*Silverspot, the Story of a Crow,” ‘‘Raggylug, the Story of a
Cottontail Rabbit,’’ ‘‘The Winnipeg Wolf’’ and others. To his
fellow specialists he is also known as a naturalist of wide experi-
ence with bird and mammal life, a serious, conscientious and
zealous field observer, and the author of a number of strictly
scientific papers on the mammals and birds of Manitoba and
other parts of Canada.
His equipment for the present undertaking is exceptional; in
addition to ability to express forcibly and concisely the results
of his observations, he has rare artistic talent, and a field ex-
perience of some thirty years, covering widely separated districts
in the United States and Canada. His sketches from life of the
poses of animals, his diagrams and plans of the underground
habitations of burrowing species, his delineations of tracks, of
dens and other habitations, and of structural characters, in
addition to his excellent plates of the animals themselves, lend
greatly to the value and interest of the text.
In the present work the popular writer’s license is laid aside
for the plain every-day narrative of actual fact. As he states in
his preface, ‘‘This aims to be a book of popular Natural History
on a strictly scientific basis.” Again he says: ‘‘ As this is a book
of Life histories or habits, I have occupied myself as little as
possible with anatomy, and have given only so much description
+¢ Life Histories of Northern Animals: An Account of the Mammals of
Manitoba.’’ By Ernest Thompson Seton, Naturalist to the Government of
Manitoba. With 68 maps and 560 drawings by the author. Published by
Charles Seribner’s Sons, New York City, 1909. 2 vols., roy. 8vo. Vol. I,
Grass-eaters, pp. i-xxx, 1-673, pls. i-xlvi, text illustrations 1-182 (many full-
page), and maps 1-38. Vol. II, Flesh-eaters, pp. i-xii, 675-1267, pls.
xlvii-e, text illustrations 183-207 (many full-page), and maps 39-68.
$18.00 net per set.
124
No. 518] NOTES AND LITERATURE 125
of each animal as is necessary for identification. My theme is
the living animal.’’
We have here, in the author’s own words, the scope and pur-
pose of the work, which is restricted to the sixty species of mam-
mals found in the province of Manitoba. They chance to in-
clude, however, most of the game and fur-bearing animals of
North America, and these have been followed into such varied
environments as the Barren Grounds of northern Canada, the
heavily forested districts to the southward, the Rocky Mountains,
the Great Plains region, and the arid southwest.
The introductory matter deals with the physical features of
Manitoba, the life-zones and faunal areas of North America (il-
lustrated with a full-page map), and with the general plan
adopted in treating the species. The descriptions of the animals
are brief but diagnostic, and with the accompanying illustra-
tions serve to give one a fair impression of the species as seen
in life. The incidents of its history are set off by side headings,
which are numerous, and vary in accordance with the diverse
traits of different species; all are defined in the introduction,
which fully connotes the author’s view-point in preparing these
life histories. The geographical range of each species is shown
by means of maps, based on patient research and indicating
present knowledge of the subject.
Mr. Seton’s ‘‘ Life Histories’’ should be of interest not only to
the naturalist, to the woodsman and to the general reader, but
to those interested in the psychology of animals. Mr. Seton
thinks that ‘‘no one who believes in evolution can doubt that
man’s mind, as well as his body, had its origin in the animals
below him’’; and with this thought in view he has sought
‘among these our lesser brethren for evidences of it—in the
rudiments of speech, sign-language, musical sense, esthetics,
amusements, home-making, social system, sanitation, wed-law,
ete.” But he adds: ‘‘As much as possible, I have kept my
theories apart from my facts, in order that the reader may judge
the former for himself.’’
His method of treatment may be illustrated by reference to his
account of the gray wolf, to which animal forty pages are given.
These include, besides the text, comparative characteristic out-
lines of gray wolf, coyote and fox as seen at a distance; a full-
page plate of the animal from a drawing from life; a full-page
map of the range of North American wolves; a full-page plate
126 THE AMERICAN NATURALIST [Vou. XLIV
of life studies of wolves (head-pieces) ; a full-page plate of a
gray wolf scratching himself (four figures) ; full-page plate of
gray wolf approaching to attack; photographs of Lobo in a trap
(half-tone plate, two views); tracks of large gray wolf (full-
page illustration); the grayhound that followed too far (full-
page plate of wolf and dog); ‘‘blood on the trail’’ (full-page
study from life) ; and tail-piece; all (except the half-tone plate)
from drawings by the author. The text gives the gray wolf’s
technical and vernacular names, its external characters and its
life history; the latter under the side-headings: range, individ-
ual range, abundanee, sociability, mating, life-long union, den,
gestation, young, maternal instinct, growth of young, feeding
young, enemies, education, history, habits, never attack man,
fishing, food, moose-killer, storage, property instinct, doping,
voice, intercommunication, smell-power, odor-glands, wolf tele-
phones, registering, expression of scorn, expression of anger,
some remarkable wolves, courage of wolves, chivalry, speed,
track, strength, swimming, social amusements, sanitation, hybrid-
ity, as training-dogs, dogginess, latent ferocity, diseases, wolf-
killing, poisoning, trapping, fur. The other species are treated
with similar detail, but the points especially considered vary, of
course, with the traits and distinctive haunts and manner of life
of different species.
The heading ‘‘never attack man’’ is somewhat modified in the `
context, for he says:
Their extreme shyness is partly a modern development, as also is the
respect for man, which now possesses every gray wolf in the cattle
country. There are many records that show the wolf to have been a
continual danger to man in the bow-and-arrow days. There can be no
doubt that then man was considered a fair prey, . . . a creature to be
eaten in times of scarcity. Consequently, each winter in America, as
in Europe, a number of human beings were killed and devoured by
hungry wolves. . . . Man with the modern gun is a different creature
from man with the bow and arrow. The wolves have learned this, and
are now no more a menace to human life than are the prairie wolves or
eoyotes. Not only do they abstain from harming man, but they have
learned that they are aea to be harmed by him, unless they keep out
of sight in the daytim
In accounting for shade pea it is not necessary to attribute human
intelligence to this animal. Evidently much hard luck and many
unpleasant surprises have engendered in it a deep and general distrust
of things strange, as well as a well-founded fear of anything that bears
No. 518] - NOTES AND LITERATURE 127
a human taint. This distrust, combined with its exquisite sense of
smell, may explain much that looks like profound sagacity in this
animal. Nevertheless, this will not explain all... .
And even ascribing much to mere shyness does not remove it from
the sphere of intelligence, though doubtless ranking it lower in that
department, making it a vague fear of the unknown, in place of a
dread of danger well comprehended.
Space does not permit further illustration of the author’s man-
ner of treatment, as illustrated in the history of the otter, fox,
beaver and of many of the burrowing species. It must suffice to
say that the amount of new information about the habits of
North American mammals set down in these two volumes is sur-
prising, with which is woven the best that has been contributed
by previous observers. No work of like character, it is safe to
say, has ever before been attempted, and doubtless many years
will pass before another like it is given to the publie. No such
persistent, prying, friendly interest has before been shown by
any student of wild mammals, whose life secrets are so much
more difficult to fathom than those of birds or insects, owing to
the nocturnal habits or shyness and secretiveness of most of the
species, and the semi-subterranean manner of living of nearly
all of the smaller forms; the squirrels and some of the larger
herbivores are almost ilie only species open to every-day obser-
vation.
J. A. ALLEN.
AMERICAN MUSEUM OF NATURAL HISTORY,
EW YORK
DO PARTHENOGENETIC EGGS OF HYMENOPTERA
PRODUCE ONLY MALES?
In view of the simple relation found to exist in the bee be-
tween the fertilization of the egg and the sex of the individual,
other hymenoptera have presented considerable difficulties. Re-
cent evidence indicates that unfertilized eggs of ants may
produce both sexes, and some species of saw-flies produce chiefly
females, others chiefly males, from unfertilized eggs. Two re-
cent papers report the results of experiments with partheno-
genetic eggs of Lysiphlebus tritici, which is parasitic on the
grain aphis, Toxoptera graminum. The first of these is entitled
‘Investigations of Toxoptera graminum and its Parasites,” by
128 THE AMERICAN NATURALIST [Vowu. XLIV
F. M. Webster, in the Annals of the Entomological Society of
America, for June, 1909. Previous experiments with lysiphlebus
had indicated that parthenogenetic eggs invariably gave rise to
males. Webster and his assistants, however, report varying
results. Females of lysiphlebus, reared in isolation to prevent
fertilization, were placed with toxoptera which had been raised
under cover to preclude previous parasitism. Of 48 such fe-
males, 44 produced only males; the other four produced females
also. The few females from these last four parents were allowed
to lay eggs under the same conditions; two of the families gave
only males, the other two again produced some females. In the
third generation one of these two families ran all to males, and
in the fourth generation the remaining family gave only males.
Similar evidence is given by S. J. Hunter in ‘‘The Green Bug
and its Enemies,’’ Bulletin of the University of Kansas, Vol.
IX., No. 2, October, 1909. The experiments were carried out
by P. A. Glenn and Miss McDaniels, and the usual precautions
were taken to prevent fertilization of lysiphlebus and parasitism
of the aphids. While some families included only males, others
had a small percentage of females. Of an aggregate of 352
individuals reared from parthenogenetic eggs, 339 were males,
13 females. Later generations seem not to have been bred from
any of these females. Among other individuals from parents
which may or may not have been fertilized, 34.5 per cent. were
males.
A. FRANKLIN SHULL.
The American Naturalist
A Monthly Journal, established in 1867, Devoted to the Advancement of the ae Eciences
Fac
with Special Reference to the
tors of Organic Evoiution and H
CONTENTS OF THE AUGUST NUMBER
The New Flora of Krakatau. Professor DOUGLAS
HOUGHTON CAMPBELL,
A Male Crayfish with Some Female Organs, Professor
E. A, ANDREWS.
Present Problems in Plant Eeology :
Problems of Local Distribution on Arid Regions.
Professor VOLNEY M. SPAULDING.
The Relation of the Bae vate minga to Vegetation.
Professor EDGAR N
Notes and Literature: Recent seare on the In-
peale ce of Coat Colors in Mice, Professor T. H.
RGAN. Some Experiments in Breedi ing Slugs.
Prafees or T, D, A, COCKERE
CONTENTS OF SEPTEMBER NUMBER
On an Early Tertiary Land-connection between North
and South America. Dr. R, F. SCHARF.
Notes on the Relations Sa eicd peg eae some of the
ping an n Zoological Dr, LLIAM HEA-
ag om Development of Starfishes on the Northwest
rican Coas ems in Evl Rept ca rd of ars
arc og ee x pout Sa Evo oe hical
Distribution : Professor yi L
Shorter Articles and Corre! ioe ya ioe a Selec-
tive Eliminakon of Ovaries Bi the Fruiting of the
Legumin : Dr. B. HAR
No and ERAKETA Tehttyology—Xohthyologieal Notes,
resident eee STARR JORDAN. Parasitology —
Potae J B. WARD. ag Cita The Per-
WARPNO of Chromosomes in Dr. BRAD-
LEY
CONTENTS OF THE OCTOBER NUMBER
The pra Articulations of Crinoids. AUSTIN
HOBART
On pra ca wid ae Plates from the Marcellus
e. BURNE
Are § Specie tain or = eee only. Professor J. H.
OWE
Shorter Articles and Discussion : a Light Weight, Port-
ASen Due fit fot the ae and Transportation of —
Epi BUCKINGHAM. Comparison of Ceno
with "Polypro otodonta and Diprotodonta. revues
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THE
AMERICAN NATURALIST
Voit. XLIV March, 1910 No. 519
THE IMPERFECTION OF DOMINANCE AND
SOME OF ITS CONSEQUENCES!
DR. C. B. DAVENPORT
STATION FOR EXPERIMENTAL EVOLUTION, Coup Sprinc Harsor, N. Y.
Ir has long been recognized that in Mendelian heredity
dominance is frequently imperfect. Mendel himself ap-
preciated this fact, for he defines dominant characters as
those ‘‘ which are transmitted entire, or almost unchanged,
in the hybridization ’’ and points out that the hybrids
between purple-red flowered and white flowered peas have
lighter flowers than the darker parent. Indeed, in his
letters to Nägeli he speaks of the hybrid-form of a char-
acter, recognizing that the hybrid character is not always
that of one parent. Practically all hybridizers of the last
nine years, and especially Correns and Bateson, have
observed and laid emphasis on this imperfection of domi-
nance. I can only add my testimony to theirs. It will
be well to illustrate the general principle by some con-
_erete examples. Bateson, and later Baur, found in
hybrids between the prickly and non-prickly capsuled
Datura that the prickles were much reduced in size.
Correns found the hybrids between green- and yellow-
leaved Mirabilis to have light green leaves; and in the
same plant, variegation, though recessive, may be detected
in the heterozygotes. Further, Mirabilis typica, 90 em.
1 A paper read before the American Society of Naturalists, December 29,
1909. :
129
130 THE AMERICAN NATURALIST [Vou. XLIV
tall, crossed with nana, 40 cm. tall, produces offspring of
70 to 85 cm., thus failing to attain the dominant stature.
Shull finds, in Shepard’s purse, the heterozygote between
elongated and non-elongated primary lobe to be imper-
fectly elongated, and the same investigator has devised a
neat chemical experiment illustrating imperfect domi-
nance. Morgan states that in hybrids between gray and
albino rats, gray fails on the belly. In Lang’s snails uni-
form shell color dominated over bands, but the hybrid
shows pale bands. In poultry, extra toe dominates im-
perfectly over normal toe; complete inhibition of shank
feathering dominates imperfectly over non-inhibition, so
that some feathers appear; median comb dominates over
absence so imperfectly that it is much reduced in the
hybrids ; dominant whites crossed with black give speckled
females. Thus, the discoverer of dominance and his fol-
lowers have generally recognized and laid emphasis on
its imperfection; and were it not for certain careless
exponents of Mendelism and a human tendency to sub-
stitute a skeleton formula for the living truth this intro-
duction might have been spared.
Of imperfection of dominance there are all degrees, as
Correns pointed out in 1905. The extreme case is com-
plete failure to dominate; it has been observed many
times. Thus Lock found that while black maize domi-
nates over white, whites are in excess of expectation in
subsequent generations and some of them prove to be
heterozygous. Lang found hybrids between red and
yellow snails to give exceptionally the recessive yellow.
In poultry, median comb crossed with no median will give
no median in 5 to 10 per cent. of the offspring. Extra
toed crossed with normal poultry give over 20 per cent.
of the recessive normal-toed type. The inhibitor of the
narial flap when crossed with narrow nostril fails to
activate in fully half of the offspring. Finally, cases are
not unknown, as in certain rumpless fowl, when the domi-
nant inhibitor has failed to act in the heterozygote com-
pletely. Several such cases have in recent years come to
No.519] THE IMPERFECTION OF DOMINANCE 131
light and it has been said that they show a reversal of
dominance, i. e., the normally recessive character has be-
come dominant. Such an expression runs counter to the
modern interpretation of dominance, which is that domi-
nance depends on the presence of a determiner, recessive-
ness on its absence. Clearly a given character can hardly
be now due to a determiner and again to its absence. The
more reasonable hypothesis is that a determiner, though
present, may fail to complete its ontogeny.
An insight into the cause of this failure is given by
modern studies in cytology and breeding. These indicate
that, ordinarily, in pure races, a well-developed, pure-
bred character has a double determiner as its embryo-
logical anlage, while in the heterozygote the determiner
is simplex. Now in just these cases when the anlage is
simplex the character develops imperfectly; and it is not
difficult to understand how, under certain circumstances,
the simplex determiner might be insufficient for the de-
velopment of the organ. Such would result in complete
failure to dominate, not a reversal of dominance.
Further proof that dominance is not reversed, but only
weakened, is derived from the facts of retardation in the
ontogeny of some heterozygotes. For example, the white
of the Leghorn is dominant over black, but, in the females
at least, the dominance is so imperfect that the plumage
of the hybrid shows many black spots or is spangled or it
may be of a uniform blue; but in later molts it becomes
pure or nearly pure white. Similarly, Lang found that
the hybrid snails between the red and yellow forms some-
times showed at first the recessive yellow, but later gained
the dominant red. The ontogeny of the heterozygote
characteristic thus appears retarded and frequently fails
altogether to reach its final goal.
This failure of the simplex determiner of the hetero-
zygote to develop the corresponding characteristic is
frequently found in one sex and not in the other. For
example, the simplex determiner for horn production in
sheep suffices to induce horns in the males but not in the
182 THE AMERICAN NATURALIST [Vou XLIV
females. In the same way the simplex determiner induces
color blindness in males but nothing less than the duplex
determiner suffices to stimulate color blindness in females.
One may say that, under the influence of testicular internal
secretions the simplex determiner suffices for develop-
ment, but not otherwise. No doubt the same is true for
many other cases of ‘‘sex-limited heredity. ’’
Imperfection of dominance goes even further. It is
evinced not only in the heterozygote but even in pure-bred
stock. This is the same as saying that, in breeding pure
stock, a character may fail to develop even when a double
determiner is present. Thus, in pure bred strains of
Houdans or Dorkings having 5 toes on each foot, from 3
to 4 per cent. of the offspring fail to develop the extra toe
on either foot. In certain races, at least, such as my
Tosa fowl, two parents, both with complete inhibition of
foot feathering, may have offspring in which this inhibitor
fails to activate, so that their feet are slightly feathered.
These cases of failure of a duplex determiner to work
itself out in ontogeny are of the nature of sports—at least
many sports are of the nature of defects arising in a pure-
bred strain. In poultry one frequently gets such defects
as failure of the neural tube to close (spina bifida), failure
of the lower jaw to develop, absence of appendages and
soon. In man, imbecility seems sometimes to occur as a
sport; and it is doubtless a typical defect, transmitted as
a recessive quality. It is probable that the same is true
of hairlessness in mammals and man (Waldeyer, 1884,
page 114, and Davenport, Science, November 20, 1908,
p. 729). Since characteristics may occasionally fail of
development in homozygotes their regular imperfection
in heterozygotes is easier to understand.
Important consequences flow from the complete failure
of a heterozygous characteristic. The first is, as pointed
out by Shull, the difficulty of determining in the first
hybrid generation what is recessive—since impotent
dominance and recessiveness yield the same result. In-
deed, one might be tempted to conclude with Shull that
No.519] THE IMPERFECTION OF DOMINANCE 133
when a character regularly fails to dominate it will never
be practicable to distinguish the dominant and recessive
conditions. But the situation is not so desperate as that
—one clear difference between dominance and recessive-
ness remains, namely, while the dominant character, even
when of duplex origin, sometimes develops fully, some-
times imperfectly, sometimes fails altogether; the homo-
zygous recessive condition yields, on the other hand,
offspring with entire absence of the quality. Since we can
not know our homozygous recessives in advance the prac-
tical method of determining them is as follows: mate
similars; some will yield families that show a great range
of variation in the given characteristic from high develop-
ment to complete absence, such are dominants or heter-
ozygotes; others will yield families that show a limited
range of conditions and will all be like the parents—such
are homozygous recessives. Their progeny are uniform
because absence of a character can not show a variability
in ontogeny.
The foregoing principle may be illustrated by an ex-
ample. In polydactyl strains no family (of over 2 indi-
viduals) from two syndacty! parents fails to produce some
normal children, but several families from two non-
syndactyl parents produce in a total of 119 offspring no
syndactyl individual. The invariable families are cer-
tainly the product of two recessive parents.
The fact of imperfect dominance bears upon the con-
troversy of alternative versus blending inheritance.
When a booted fowl is mated to a clean-shanked one the
offspring show grades of boot ranging from 0 to 9;—10
being the heaviest grade recognized. For example, when
a Cochin is crossed with a White Leghorn the average
grade of booting is about 4 on a scale of ten. Booting
would seem to be a typical blending character. Yet the
evidence of segregation.is excellent. For, two extracted
recessives (full-booted) beget no clean shanked offspring.
DR X RR gives 50 per cent. of the offspring of grade 5
or over, DR X DR yields 25 per cent. of grade 5 or over,
134 THE AMERICAN NATURALIST [ Vou. XLIV
while DR X DD gives none in- these grades. <A similar
result is found in the apparently blending character of
nostril height. May not segregation occur in the cases
of apparent blending? Does not true blending occur only
in complex characters such as stature and skeletal weight?
Of such character complexes the component units may
still segregate.
Finally, the fact of imperfect dominance leads to an
explanation of many puzzling cases of apparent failure of
inheritance. Some years ago I bought two tailless cocks
A and B, of which B was said to be the son of A. They
were certainly very similar in appearance. I mated A to
some tailed hens and their offspring were tailed. The
next year I mated these hybrids with each other and the
females with their father. Were taillessness recessive,
as I suspected, one-fourth of the progeny of the first
mating and half of the progeny of the second should have
been tailless. Actually there was produced not one
tailless bird. One would apparently have been justified
in concluding that taillessness is not an inheritable condi-
tion. But when the second tailless cock was mated with
the tailless hybrids approximately half of the offspring
were tailless; and such tailless offspring bred inter se
have in turn produced a large proportion of tailless
progeny. This whole case at first seemed inexplicable to
me, as it did to Professor Bateson, to whom I related it,
but it receives a satisfactory interpretation on the theory
of imperfect dominance. For rumplessness, or rather
an inhibitor of tail growth, is dominant over its absence.
But with cock A this inhibitor is so impotent that in the
heterozygote, at least, it does not make itself felt and
even in the second hybrid generation the duplex de-
terminer fails to activate fully. I say fully, for there
was a trace of activity. At least fifteen per cent. of the
offspring were recorded as having a small uropygium and
in many of the adults the back appeared shortened and
bent and the tail drooped instead of standing erect. De-
spite these evidences of the activity of the inhibitor, the
No. 519] THE IMPERFECTION OF DOMINANCE 135
striking fact is that its activity is so feeble that it cannot
prevent the development of the tail. In the case of the -
second cock, however, the inhibitor is stronger and be-
haves more nearly according to Mendelian expectation.
Now, if a character can be so feeble as to fail completely
in development in the heterozygote and even in the homo-
zygote it will give the impression of non-inheritability ;
and I have little doubt that many cases in which there is
apparently no or only a slight inheritance are due to a
weak determiner. I could cite a considerable number of
cases of this sort in my experience, but I refer for an ac-
count of them to a book that is being published for me by
the Carnegie Institution of Washington. Still one other
lesson may be drawn and that is the apparent variability
in what I call the potency of determiners. The evidence
for this potency seems to me to be strong, as it certainly
is important for an interpretation of all non-Mendelian
cases of heredity. By the aid of the facts of imper-
fection in dominance and the hypothesis of varying
potency of determiners the territory to which the prin-
ciple of the segregation of determiners is applicable
becomes greatly extended.
EXPERIMENTAL EVIDENCE ON THE EFFECT-
IVENESS OF SELECTION!
PROFESSOR H. 8. JENNINGS
JOHNS HOPKINS UNIVERSITY
In studying the problems of evolution in the common
infusorian Paramecium, I found that by methodical and
progressive selection striking results can be reached.
From a wild culture it is possible by progressively
selecting in two opposite directions to obtain finally two
lots, one of which is many times as large as the other,
and the differences between the two are permanent and
hereditary. By properly regulated selection a great
variety of permanently differentiated lots are obtainable.
Throughout this work Galton’s law of regression was
found to hold; that is, the progeny of extreme parents
inherited the peculiarities of their parents, but in a less
marked degree. Furthermore, the results were such
as to lend themselves readily to interpretation as ex-
emplifying Galton’s law of ancestral heredity.
Thus the effectiveness of selection was clearly demon-
strated. But just what sort of effectiveness does the
theory that selection is the dynamic factor in evolution
demand? It demands that selection shall so act that
it might finally produce progress from Ameba up to
man. It must produce, from a given condition, some-
thing that did not before exist in that given condition.
Has selection so acted in this case? ‘To answer this
question, we must evidently know precisely what exists
in the condition with which we start. We therefore next
work with the progeny of a single individual—forming
a ‘‘ pure line,’’ the characteristics of which we thoroughly
know. .
Now we try the effects of selection on this pure line.
*A paper read before the American Society of Naturalists, December
29, 1909. |
136
No.519] THE EFFECTIVENESS OF SELECTION 137
Not the faintest trace of effect is produced, even by long-
continued methodical selection for hundreds of genera-
tions. The race or line is absolutely permanent, so far
as the appearance of any hereditary differences are con-
cerned. The individuals of the line do indeed differ
greatly among themselves, but these differences are not
inherited; they furnish absolutely no foothold for selec-
tion.
Examination showed that Paramecium consists of
many such races, differing among themselves slightly,
but each race as unyielding as iron. And the extreme
races found in the wild culture are precisely the extremes
obtainable by long-continued selection.
The effects of selection have then consisted simply and
solely in isolating races that already existed. It had
produced nothing new; there had been no progress that
would form a step, however slight, in the journey from
Ameba to man. 3
When I had reached this point I looked about and
found that others had been having similar experiences.
The investigator who discovers these things for himself
finds perhaps that
Es ist eine alte Geschichte
Doch bleibt sie immer neu.
And the second line is as true as the first, for to one
who has put months and years on such attempts to accom-
plish results by methodical selection, its utter powerless-
ness comes with new and surprising force. Johannsen
in working with beans and barley, Hanel with Hydra,
had found many pure lines existing in nature, but as in
my own case, each pure line was absolutely unyielding.
But we know that others had found selection effective;
a whole series of cases comes at once to our lips. Galton
in studying peas and men; Fritz Miiller with maize; de
Vries with maize and with buttereups, MacCurdy and
Castle with guinea pigs and rats—all these had reported
definite progress as a result of methodical selection.
138 THE AMERICAN NATURALIST [Vou.XLIV
Why this difference? Is there one law for the Jews,
another for the Gentiles?
Looking into the matter with care, we find that the
results with our own material are, after all, like those
of the investigators mentioned if we treat it in the same
way. None of these workers first isolated their pure
races. If we begin with a mixture we can, in beans, in
barley, in Paramecium, in Hydra, by a methodical proc-
ess of slow selection make gradual progress in a certain
direction. But our selection is only a process of purifica-
tion, and when we finally get a pure race, selection is
utterly powerless to go farther. We should have been
completely in the dark as to the real effect of selection
if we had not carried through rigidly the ‘‘pure line’’
idea.
Is it possible then that we have in this pure line idea
an instrument of the greatest importance for analysis?
Is it perhaps the key which every one must have in order
to understand the results of selection? May it be indeed
one of those fundamental ideas which, like the idea of
mutation, is fitted to clear and erystallize a confused and
turbid mixture? Is it possibly of sufficient importance
to deserve agitating a little before the American Society
of Naturalists?
Let us put these questions to the practical test; let
us apply the idea as an instrument for the dissection of
the classic cases which seem to demonstrate the efficacy
of selection in producing change of type.
Johannsen in his recent book has used the pure line
concept as an instrument for analysis of the entire field
of variation, heredity and evolution, and to him is due
the credit of first perceiving the importance of this con-
cept, when sharply defined, as such an instrument for
research and presentation. The work of Johannsen, I
believe, will remain one of the landmarks of progress
in this field. But my own analysis has been independent
of Johannsen’s and diverse from it, developing inevit-
ably from what I have myself seen, so that I may ven-
ture still to present some of its results.
No. 519] THE EFFECTIVENESS OF SELECTION 139
But how can we apply the pure line idea to organisms
whose lines are not pure; organisms that interbreed
freely; organisms in which the characters of a given
line split off, separate, and become exchanged for those
of other lines, in the way characteristic of Mendelian
inheritance?
The pure line idea here becomes a little elusive, a
little abstract. But possibly it is still helpful as an
instrument of analysis; let us try it. In order not to
emphasize purity where impurity is the rule, let us sub-
stitute Johannsen’s term genotype for ‘‘pure line’’—
defining the genotype as a set of individuals which, so
long as they are interbred, produce progeny that are
characteristically uniform in their hereditary features,
not systematically splitting into diverse groups.
Now, how can we determine whether the genotype con-
cept, with its consequences for the effects of selection,
applies to organisms with biparental inheritance? Re-
flection shows that if it does, certain general propositions
are true: if these propositions are found to hold, the
genotypic explanation of the effects of selection is con-
firmed.
1. The first proposition is this: Organisms in which
selection has shown itself effective are composed of many
genotypes; of many races that are diverse in their heredi-
tary characters. This we know to be true.
2. Second, from such a mixture of genotypes it is pos-
sible to isolate by selection any of the things that are
present—perhaps in a great number of different com-
binations.
3. But from such a mixture it is not possible to get by
methodical selection anything not present (save when
rare mutations have occurred).
4. Therefore it is not possible to get by methodical
selection anything lying outside the extremes of the
genotypic characters already existing. |
This is perhaps practically our most important propo-
sition. For in order that selection shall produce pro-
140 THE AMERICAN NATURALIST [Vou. XLIV
gression from Ameba to man, it is evidently necessary
that it should give us characters lying beyond the ex-
tremes of what already exists.
5. Our fifth proposition is that in the case of genotypes
that cross-breed readily, we may get an indefinite num-
ber of combinations of all that lies between the extremes
of the existing genotypes—the variety of combinations
realized depending on the rules of inheritance.
Now, if we test by these propositions the classic cases
of effective selection, what is the result?
Galton’s work with peas and with men yields at once
to the analysis, giving precisely the results which the
genotypic idea requires. A by-product of the analysis
is the practical evaporation of the laws of regression and
of ancestral inheritance so far as their supposed physio-
logical significance is concerned; they are found to be
the product mainly of a lack of distinction between two
absolutely diverse things—between non-heritable fluctua-
tions on the one hand, and permanent genotypic differen-
tiations on the other. |
The experiments of Miiller and de Vries on maize yield
with equal readiness. In these cases the male parents
are unknown; the freest sort of crossing was occurring,
and what selection did was pick out the progeny of ex-
treme male genotypes, till the result approached the limit
of the most extreme existing genotype under the cultural
conditions.
MacCurdy and Castle’s experiments in changing by
selection the color-patterns of rats and guinea-pigs dealt
? This significance was supposed to lie in showing that the characteristics
of the progeny depend upon the characteristics of the ancestors y
generations back, in ways that are definable. ‘‘ Mr. Galton’s view we the
effect of regression follows inevitably from the general theory of chance,
if we regard the character of an individual as a phenomenon due to a series
of complex groups of causes, among which are the characters of each
ancestor.’’ (W. F. R. Weldon, Biometrika, I, p. 370.)
The law ot ancestral TEE does not hold in pure lines, even in a
statistical sense, as has repeatedly been shown. The progress of a long
series of extreme ancestors does not differ from those of a series of average
neestors.
No.519] THE EFFECTIVENESS OF SELECTION 141 °
with races of complicated descent; they plunge us at once
into all the difficulties due to interweaving, blending and
transfer of characters from one genotype to another.
But if we stick closely to the general propositions already
stated, we shall have a guide. MacCurdy and Castle
got by selection all sorts of conditions lying between the
extremes with which they started. But did they get any-
thing lying outside these extremes, as would be required
in order to show that we can by selection make evolu-
tionary progress? As I read their results, they did not.
Their experiments are most important for many prob-
lems of variation and inheritance, but they do not give
us evidence that methodical selection can produce any-
thing beyond combinations of what already exists; hence
they do not help us in getting from Ameba to man.
The work of the German breeders who have for years
practised methodical selection for improvement of agri-
cultural races clears up at once under the genotype idea,
as the analyses of Fruwirth, v. Riimker and others show
us. Continued methodical selection is often necessary,
but what it does is to purify a contaminated race—a |
process which, owing to the laws of inheritance, may re-
quire several generations.
I have spoken only of those experiments which seem
at first view to show the efficacy of selection; brevity
requires me to pass, without mention over investigations
which, while not carried on with pure lines, support and
reinforce the conclusions drawn from such work. Such
for example are the fundamental experiments of Tower,
the recent work of Pearl, of Shull, and many of the experi-
ments of de Vries.
Thus far the dissecting knife of the pure line idea
succeeds admirably in letting the light into the obscure
workings of selection. Any one who uses it with pre-
cision will find what an important advance its exact
formulation by Johannsen marks over even such an
analysis as that given by de Vries. In the work of de
Vries, as in that of many recent authors, the selection
ia THE AMERICAN NATURALIST [Vow XLIV
idea is appraised at essentially its true value, but much
in its action is left obscure. The reader is surprised at
the accounts of experiments in which selection does ac-
complish marked results, though according to the general
theory, it should not; one is left puzzled in judgment as
to what we may expect from it. With the sharply formu-
lated pure line concept as a guide, most of this obscurity
disappears.
And then, to keep us from resting on our oars; to give
us humility and spur us to further work—we come to the
one case in which the pure line idea fails to bring clear-
ness. This is de Vries’s experiment with buttercups.
Here, after selection the extreme was moved far beyond
that before selection. Before selection the extreme num-
ber of petals was eleven; after selection it was thirty-
one. Before selection no single individual had an aver-
age number of petals above six; after selection the aver-
age of all was above nine, and some had an average of-
thirteen! It is true that there are ‘‘mitigating circum-
stances’’ here; the work was not done with pure lines,
and the variations dealt with are not of the ordinary
fluctuating sort (as de Vries points out); change in cul-.
tural conditions doubtless played also a large part. Pos-
sibly repetition with thorough analytical experimentation
will show that something besides selection has brought
about the great changes. But at present the case stands ~
sharply against the generalizations from the pure line
work. It is the only such case that I have found.
To sum up, one finds not only that his own results and
those of many other modern workers give the pure line
interpretation, but also that all other cases that had
seemed to point the other way yield readily to the geno-
typic analysis—save one. If we ride rough shod over
this case, as not yet sufficiently studied, then we may
draw a tentative conclusion as follows:
The pure line or genotype idea is the one to see clearly
and grasp firmly in experimental investigations on selec-
tion. Many even of the modern experiments remain
No.519] THE EFFECTIVENESS OF SELECTION 143
obscure in their significance simply because the workers
have not grasped this concept, have not shown the rela-
tion of their results to it. Further, in presenting one’s
own work, or in interpreting the accounts of others, the
genotype concept is the instrument of precision to take
in hand. The results of the analysis made by its aid
indicate that most or all of the experiments in methodical
selection have consisted in shifting about, isolating and
recombining preexisting, permanent hereditary differ-
entiations, giving results that were interpreted as re-
vealing the law of actually progressive evolution, though
in reality they had no relation to such a law.
To our conclusion as to the analytical value of the pure
line idea we may expect strenuous opposition on the part
of that last small remnant (if there be such a remnant)
of the biometrical school that still submits to the dictation
of Pearson’—for by one of those sardonic paradoxes
through which nature revenges herself, the men who
from outside have lectured biology on the necessity of
becoming exact are the strongest opponents of exact ex-
perimental and biological analysis—seeming to feel that
mathematical treatment renders other kinds of exactness
undesirable.* Those who find the genotype idea useful
may then prepare themselves for one of those justly
famous bludgeonings from the dictator of the whilom
orthodox biometrical school; this is the last honorable
mark of distinction which stamps the investigator as a
thorough and exact analyst of things biological.’
3 Note how quickly the biometricians that devote themselves to careful
ol investigations fall away from. the Pearsonian faith. Darbishire,
venport, Tower, Shull, Johannsen, Pearl; are there any biologists o
sieve that still hold with Pearson
*Pearson in 1901 informs us that evolution is a field ‘‘ where no tabu-
lation of individual instances can possibly lead to definite conclusions ’’
(Biometrika, I, p. 344). This was the year of the appearance of de Vri ries’s
Mutationstheorie, and of the revival of Mendelism. Compare in definite-
ness and value the conclusions drawn from the work inaugurated in these
two lines, based as it was precisely on the ‘‘ tabulation of individual
instances,’’ with those from the biometrical work, with its careful avoidance
of ‘‘ individual instances. ’’
š To name the men who have been subjected to Pearson’s most savage
144 THE AMERICAN NATURALIST (Von: XLIV
A word more on certain general questions. Can we
conclude that if selection has no dynamic effect in chang-
ing existing genotypes, that therefore it need not be
reckoned with in evolution? Or must we conclude that
if it is to be reckoned with at all, selection has oppor-
tunity to act only on large leaps in evolution; that evolu-
tion takes place by such leaps, and not by imperceptibly
small changes?
Such evidence as the pure line work gives implies
neither of these things. The differences between the
diverse pure lines have arisen in some way, if evolution
occurs, and once these differences have arisen, they are
open to the operation of selection as are any other dif-
ferences. What the pure line work shows (agreeing
in this with other lines of evidence) is that the changes
on which selection may act are few and far between,
instead of abundant; that they are found not oftener
than in one individual in ten thousand, instead of being
exhibited on comparing any two specimens; that a large
share of the differences between individuals are not of
significance for selection or evolution—these being pre-
cisely the differences measured as a rule by the bio-
metrician’s ‘‘coefficient of variation.” Thus the work
of natural selection is made infinitely more difficult and
slow; but logically it is still possible.
Nor does the pure line work assist natural selection,
as some have hoped from the mutation work, by making
the steps in evolution greater in amount. On the con-
trary, the work with genotypes brings out as never be-
fore the minuteness of the hereditary differences that
separate the various lines. These differences are the
smallest that can possibly be detected by refined meas-
urements taken in connection with statistical treatment.
Johannsen found his genotypes of beans differing con-
stantly merely by weights of two or three hundredths
of a gram in the average weight of the seed. Genotypes
assaults is to name the men that have done most to advance our knowledge
- of heredity. The cases of Castle and of Bateson will occur to every
zoologist.
No.519] THE EFFECTIVENESS OF SELECTION 145
of Paramecium I found to show constant hereditary dif-
ferences of one two-hundredth of a millimeter in length.
Hanel found the genotypes of Hydra to differ in the
average number of tentacles merely by the fraction of
a tentacle. That even smaller hereditary differences are
not described is certainly due only to the impossibility
of more accurate measurements; the observed differ-
ences go straight down to the limits set by the probable
error of our measures. Genotypes so differing have not
risen from one another by large mutations. The geno-
typic work lends no support to the idea that evolution
occurs by large steps, for it reveals a continuous series
of the minutest differences between great numbers of
existing races.
All together, I think we may say that the pure line or
genotype concept presents an instrument of analysis
which is worthy, on the basis of what it has thus far
done, of a thorough tryout for future work, and no one
interested in these questions can afford to neglect it.
This conclusion is quite independent of the concrete re-
sults reached; the efficacy of selection in modifying geno-
types may be demonstrated to-morrow, but the demon-
strators will need to show precisely the relation of their
results to the pure line concept.
THE ARTIFICIAL PRODUCTION OF THE PAR-
THENOGENETIC AND SEXUAL PHASES OF
THE LIFE CYCLE OF HYDATINA SENTA
A. FRANKLIN SHULL
CoLUMBIA UNIVERSITY
THE causes that determine the transition from the
parthenogenetic to the sexual mode of reproduction in
the rotifer Hydatina senta have been the subject of a
number of investigations, which have led to contradic-
tory conclusions. Maupas was led to attribute the ap-
pearance of sexual forms to changes of temperature,
Nussbaum to starvation. Punnett found that neither
temperature changes nor starvation had any effect, but
obtained what seemed to be distinct strains, each pro-
ducing a fairly constant proportion of sexual forms, re-
gardless of external conditions. One strain produced
many sexual females (about 40 per cent.), another few
sexual females (2 per cent.), and a third none at all.
His conclusions regarding temperature and starvation
were supported by Whitney, but the latter worker ob-
tained no evidence of strains, finding that so-called
strains of one type might break up into those of any
other type within a single parthenogenetic series.
I believe I have evidence which may explain the diffi-
culties hitherto encountered, evidence that goes far
towards bringing the previous contradictory conclusions
under a single point of view. I shall attempt to show
in this brief presentation that the presence of substances
in the water, other than food, exerts a strong influence
on the inauguration of the sexual phase.
In this paper I shall speak of the male-producers as
sexual females. The identity of the two has long been
suspected from certain numerical relations, but more
146
No.519] THE LIFE CYCLE OF HYDATINA SENTA 147
direct observations have been wanting. I have now,
however, been able to secure winter eggs and males from
the same parent. Since in all cases known, a female
lays parthenogenetic eggs of only one sex, there can be
little doubt that sexual eggs and male eggs are identical.
To test the influence of substances in the food cultures,
lines of rotifers were reared in the water of some old
cultures, from which the protozoa had been removed by
filtering. Various dilutions of this water were used, one
fourth, one half, three fourths and undiluted, as well as
pure spring water. The same kind and quantity of
food, a flagellate, Polytoma uvella, was added to each,
and was found to live readily in all concentrations of
the filtrate. The results of eight or more generations
bred simultaneously under these conditions are shown
in Table I.
TABLE I
SPRING OLD CULTURE FILTRATE.
WATER.
One fourth. | One half. | Three fourths. | Undiluted.
Sex. Parth. Sex.|Parth. Sex.|Parth.| Sex. |Parth. Sex. Parth.
foe te Ss TERR arip
|9]
BEA r
| 0 | 337
| 0.0
-26 | 177 |25 | 407 |15| 350 | 8 | 862
Per cent. Sex.9| 12.8 pt opo ti 2.1
There is a gradual decrease in the proportion of sexual
females from the line bred in pure spring water to that
in the undiluted filtrate. The series in the dilute filtrate
were discontinued at this point, but those in spring water
and in concentrated filtrate were continued. In the
latter line, nineteen complete generations were obtained
without a single sexual female, while in spring water the
sexual forms recurred at intervals, though not frequently,
to the end of the experiment.
The experiment was repeated by removing to spring
water a female of the seventh generation of the series
bred, in the preceding experiment, in concentrated fil-
trate. The results of this change are shown in Table II.
Six generations were reared in each line.
148 - THE AMERICAN NATURALIST [ Vou. XLIV
TABLE H
SPRING WATER. OLD CULTURE FILTRATE.
Sex. ?. | Parth. ọ .| Per cent. Sex. 9,
Sex. Q. Parth. 9.| Per cent. Sex. Q.
0.0
|
|
|
| |
33 | (216 | 13.2 | ieee ae
From the third generation of the series in spring water
in Table II, a female was returned to the concentrated
filtrate, and her progeny reared for three generations.
A control was continued in spring water. The results
are those in Table III.
Tapes IIT
SPRING WATER. | OLD CULTURE FILTRATE.
|
| | mit
Sex. 9°. | Parth. 9.) Per cent. Sex. Ẹ. | Sex. 9. | Parth. Q .| Per cent. Sex. 9.
7 | 110 | 5.9 ip Oo AMEE 0.0
The experiment was repeated four times, with sisters
in each case, derived from lines more or less distantly
related to those in the preceding experiments. These
are recorded in Table IV.
TaBe IV
SPRING WATER. OLD CULTURE FILTRATE.
bie Sex. 9, | Parth. Ọ. | Per cent. Sex. 9, Sex. 9, | Parth. 9, | Percent. Sex. Ọ ,
1 44 163 21.2 0 141 0.0
2 49 64 43.3 0 128 0.0
3 ja 106 6.1 0 103 0.0
4 5 76 6.1 | 0 85 0.0
In every case, the evidence points to the same con-
clusion, namely, that the filtrate from the old cultures
reduces the number of sexual females. The losses by
death are too few to account for the results obtained,
and there is evidence to show that what deaths there are
are not selective.
It is interesting to note the bearing of the above evi-
No.519] THE LIFE CYCLE OF HYDATINA SENTA 149
dence on the question of starvation. It is not practicable
to diminish the quantity of food placed in the dishes,
without at the same time diminishing the quantity of
other substances introduced. Several experiments were
made to test the apparent effect of starvation. When
the young were isolated, they were given only as much
food as was judged necessary to support life and enable
them to produce a moderate family. A control line,
which was fed abundantly from the same cultures, was
maintained in each case. One experiment, Table V,
included 55 generations and covered a period of three
months. In this time, the well-fed control varied so
greatly in the proportion of sexual to parthenogenetic
females produced, that it is important, not merely to
note the totals, but to divide the experiment into periods,
and compare the results in each.
Taste V
| WELL-FED. STARVED.
Limiting Dates. R E Lear
gaw | Sex. Q | Parth. 2 a Sex. Ọ | Parth. 9 sole
| E
July 23-July 27 127 73 63.5 72 47 60.5
July 28-Aug. 25 50 754 0.6 125 265 32.0
‘Aug. 26-Sept. 5| 129 153 | 45.7 55 80 40.7
Sept. 6-Sept. 20 35 203 14.7 34 100 25.3
Sept. 21-Oct. 12 187 261 41.7 93 157 35.2
Oct. 13-Oct. 25 25 208 10.7 87 161 35.0
Total 553 | 1,652 | 25.0 466 | 810 | 36.5
While the experiment as a whole shows a decidedly
higher percentage of sexual forms in the starved families,
there are parts of it that show a slightly lower proportion
in the starved line. The variation in the percentage of
sexual females from one period to the next in the starved
line is of the same sign as in the corresponding periods
of the well-fed line, but is smaller in every case. While
the major fluctuations of the starved line occur simul-
taneously with those of the well-fed line, they are less
in degree; the extremes of the starved series are always
well within those of the well-fed. I can find only one
150 THE AMERICAN NATURALIST [Vou. XLIV
factor which operated on both lines in the same way,
but to less degree in one line than the other, namely, the
food culture.
Of especial interest are the second and sixth periods
Table V. In these, not only the percentage, but also the
absolute number, of sexual females is higher among the
starved individuals. This shows that the percentage is
not raised by the mere elimination of some of the parthen-
ogenetic females.
The experiment with starvation was repeated three
times, each repetition including eight to sixteen genera-
tions. Each time there was a considerably higher pro-
portion of sexual females in the starved families.
While it is conceivable that several factors may be at
work producing these different proportions of sexual to
parthenogenetic forms in the well-fed and starved fam-
ilies, the experiments with the filtrate from old food
cultures show that the different quantity of dissolved
substances incidentally given with the food is sufficient
to explain the results. If this is the correct interpreta-
tion, the larger proportion of sexual forms in the starved
families is not due to lack of food, but to the absence
of chemicals which, in the well-fed families, prevent the
appearance of the Ferna forms.
THE SIGNIFICANCE OF THE COURTSHIP AND
SECONDARY SEXUAL CHARACTERS OF
ARANEADS*
PROFESSOR THOS. H. MONTGOMERY, JR.
UNIVERSITY OF PENNSYLVANIA
But few observers have made special studies in those
phenomena in spiders of which it is proposed to treat
in the present communication. The first studies, by
Canestrini, were inaccessible to me. The main work on
the subject is that of Professor and Mrs. Peckham
(1889, 1890). They have described in great detail the
courtship of a considerable number of Attide, and have
given excellent illustrations of the attitudes of the males.
Then after an analysis of the phenomena in question they
have criticized the views of Wallace (1889), and have
accepted that part of the sexual selection theory of Dar-
-= win which accounts for secondary sexual differences on
the basis of an esthetic discrimination by the female.
The results of these studies have been generally accepted
as one of the strongest confirmations of Darwin’s views.
In the introduction to their last memoir (1909) they have
reiterated their arguments, with the addition of certain
new and important observations. The next special work
on this subject is my paper of 1903, in which is described
in detail the courtship of certain lycosids, agelenids,
dictynids, theridiids, pholcids, epeirids and thomisids.
My general theoretical conclusions were quite different
from those of the Peckhams: the adult male is excited
simultaneously by fear of and desire for the female, and
his courtship motions ‘‘are for the most part exaggera-
tions of ordinary motions of fear and timidity. By such
motions he advertises himself to the female as a male, but
1 This paper was presented before the American Society of Naturalists,
Boston, Mass., December 29, 1909.
151
152 THE AMERICAN NATURALIST [Vou. XLIV
there is no proof that he consciously seeks to arouse her
eagerness by esthetic display ... there seems to be
no good reason to hold that the female is actuated in her
choice by sensations of beauty.’? Thus my opinion was
opposed to Darwin’s theory. ‘The remainder of the
literature on the secondary sexual phenomena of
araneads contains for the most part only casual observa-
tions, without attempts at analysis.
I. Some GeneraL Matina RELATIONS
For a correct understanding of the points at issue it
would be very desirable to have ample data on the
numerical proportions of the sexes, but unfortunately
little is known on this head. What is known is brought
together in another paper of mine (1908a); and there
also it was found in the case of Lathrodectus mactans
that the ‘‘average male ratio (number of the males
divided by the number of the females) is 8.19, deter-
mined from a count of 41,749 newly hatched spiderlings.’’
In this species the adults differ most markedly, and the
young emerging from a cocoon are readily separable into
two groups, distinguishable not only by size relations, but
also, as specially indicated by me, by differences in the
form proportions of the abdomina. Those spiderlings
with a flatter dorsum and more anterior pedicel were
considered to be males, for this is one of the characters
in which the adults differ. However, none of these
spiderlings were raised to maturity, though the attempt
was made to do so; no differences in the internal genital
organs can be found at the time of hatching, and occa-
sionally (though rarely) nearly intermediate forms occur
between the two groups of spiderlings. There is then
room for doubt whether the two groups represent males
and females, respectively, and the sex-ratio is not securely
established from my results; it is rather in the nature
of a strong probability. Beyond this case nothing
definite is known about the numerical proportions of the
sexes.
No. 519] THE COURTSHIP OF ARANEADS 153
It is the general rule that the males mature earlier
than the females, and the former do not live longer than
a year. Promiscuous mating is general, a male im-
pregnating a number of females, and a female receiving
a number of males. I have seen a female of Geotrecha
pinnata mating with two males in close alternation, two
males of the theridiid Ceratinopsis interpres embracing
a female simultaneously, and I have described (1903) for
Theridium tepidariorum as many as twenty-seven im-
pregnations of one female. In the attid Phidippus
purpuratus one male was seen by me to fertilize several
females. Monogamy is exceptional, and would appear
to occur in cases where the male seizes immature females
by foree, and where the male lives in a mating nest with
a female. Many attids make such nests; in the case of
Phidippus purpuratus I have frequently found pairs in
such nests in the wild state but never found them to
make such nests in captivity, where there is on the
contrary promiscuous mating. MeCook (1890) has
brought together some of the literature on mating nests.
In certain cases an adult male seeks out and sequestrates
an immature female, mating with her when she matures.
The Peckhams (1889) found the only attid under their
observation, ‘‘in which we saw males take possession of
' young females and keep guard over them until they
became mature,’’? to be Phileus militaris. A pair of
Drassus neglectus was caught by me in a mating nest
on June 16, last, and placed in a cage, where he built
another nest around her; on June 23 he mated with her
when she had just finished moulting and was still quite
soft; in another case a male and an immature female
were found in the same nest. A mature male of an-
other drassid, Prosthesima atra, was repeatedly observed
by me to hold an immature female, and on another occa-
sion to grasp two such at once. In Theridium tepi-
dariorum adult males wait upon the snares of immature
females, and this has been seen by McCook (1890) and
me in various epeirids. In Lycosa ocreata I found that
154 THE AMERICAN NATURALIST [Vou. XLIV
males pay no attention to immature females, while they
do in L. scutulata. During the past summer I have seen
males courting immature females in the attid Zygoballus
beltini, the thomisid Xysticus nervosus, and the drassid
Chiracanthium inclusum.
In some species, as notably epeirids and lycosids,
pregnant females are hostile to males. But I have seen
such females of Theridium tepidariorum and Phidippus
purpuratus receive males, and on one occasion a female
of Geotrecha pinnata was interrupted several times during
her cocooning by embraces of a male. Males appear to
court any mature female, whether she be virgin or not.
II. Senses EMPLOYED IN SExUAL RECOGNITION AND
STIMULATION
Here we have to consider briefly the rôles of hearing,
touch, sight and smell.
There is no good evidence:-that spiders possess hear-
ing, while the arguments of Wagner (1888) and espe-
cially the direct observations of Pritchett (1905, done
under my direction) speak almost conclusively against
such possession. Some spiders have stridulating organs,
and in certain species these are limited to the male
(Theridium, according to Westring), but no experi-
ments have been made to determine whether the spiders
react to the sounds produced thereby. I have recently
found in the drassid genus Geotrecha, where both sexes
possess a stridulating apparatus, the spiders do not in
any way indicate any perception of sound but perceive
each other solely by touch. It is then fairly firmly
established that the sexes do not recognize each other
by hearing.
Touch is the dominant sense, and would appear to be
the especial function of the jointed spines. In nocturnal
species as well as in all snare-weavers it appears to be
the only sense of sex-recognition. :
Smell is possessed by spiders, but what organs sub-
No. 519] THE COURTSHIP OF ARANEADS 155
serve it is not determined, beyond that it seems to be
distributed over a considerable area of the body. The
most careful study of it has been made by Pritchett
(1905), while Petrunkeviteh (1907) found it to be less
keen than touch. It might be this sense that guides
wandering males in their search for females. But I am
inclined to believe it does not, for of pairs I have
watched attentively in cages the male always appeared
to find the female by either touch or sight, while if he
is near her, but without seeing or touching her, he seems
unconscious of her proximity. Further, when in the
wild state a male approaches a female upon her snare,
there seems to be no evidence that he constantly ap-
proaches her in the direction of the wind. Thus it is
very doubtful whether scent has any part in sex-recogni-
tion in spiders, while it is the most usual mode of sex-
recognition in insects.
Sight undoubtedly plays a considerable part in sex-
recognition in certain diurnal species, determined for the
attids by the Peckhams, and for the lycosids by me.
These spiders, however, perceive readily only moving
objects. But, as we shall see, it is not used for this
purpose in the other spider families, not even in the
diurnal thomisids. Thus I can not agree with Petrunke-
vitch’s conclusion (1907) that ‘‘the sense of sight is
beyond any doubt the only sense that guides hunting
spiders on their hunting excursions and in finding the
females during the mating period,’’ for I have frequently
noticed males of even diurnal attids and lycosids first
recognizing the female by touch. And in the case of
Pardosa nigripalpis, a species that always courts by
light, it was remarked by me (1903): ‘‘In a double cage
with a transparent glass partition, a male in one compart-
ment and a female in the other, I have not seen a male
court a female, though he certainly sees her through the
partition; probably, then, it is touch of a female that
‘impels him to courting activity.” Numerous pairs were
kept by me in such cages to test this point.
156 THE AMERICAN NATURALIST [Vou. XLIV
The senses of sex-recognition are, accordingly, touch
in the first place and sight in the second, the latter im-
portant in only a few families.
Ill. DETAILS or THE COURTSHIP PHENOMENA
It will be convenient for our present purposes, for it
is based upon habitudinal differences, to divide the
species on which observations have been made into the
two catégories of ‘‘snarers’’ and ‘‘hunters.’’ The lit-
erature on the subject has been gleaned as thoroughly
as possible; and my new observations of the past summer
have been presented more fully than the others simply
because they are here given for the first time.
1. Snarers
In Dictyna volupis Keys. mature males and females
live together upon the web, which they appear to fabri-
cate in common; the male is somewhat larger. In two
cases the approach of the sexes was seen by me (1903) :
in one the male approached and seized the female; in
the other case a male came face to face with a female,
‘‘then, each of them tapping upon the web with the
first two pairs of legs, they moved backward and forward
slowly. This lasted only two minutes, when they both
became quiet half an inch apart; it was repeated again
for a short period.’’ These are the only observations
on any cribellate form, and they do not indicate clearly
whether rape or courtship by the male is the usual
process.
For the Agelenids Menge (1843) described the ap-
proach of the male in Agelena labyrinthica as follows:
The male climbs into the web of the female, taps on it
with his palpi, but must sometimes wait for an hour be-
fore the female allows him to approach. ‘‘ When she is
complacent she places her legs close to her side, and the
male embraces her with his legs and carries her into-
the funnel.” In A. nevia Walck., I saw the approach
No. 519] THE COURTSHIP OF ARANEADS 157
of the male in two cases; in both there was nothing ‘‘to
indicate a courtship; there was simply a cautious ap-
proach of the male,’’ he touched her with his first legs,
“and after he had found no sign of hostility on the
part of the female he quickly seized her, and she was
absolutely submissive in his grasp.” In Tegenaria
durhami Seop., in several cases, the male was seen by
me to slowly approach the female upon her web, he
tapping the latter with his fore legs as he advanced, the
female occasionally also tapping in response, after which
he would make a sudden rush at her. In these agelenids
there are no courtship motions beyond tapping on the
web, to which the female may respond, in like manner;
the male seems to find her by touch, and after a cautious
approach to seize her forcibly.
In Pholcus phalangioides Fuessl. I found (1903) no
courtship; the male approaches the female very cau-
tiously upon her web, and touches her gently with his
legs; he always approaches her from beneath, and im-
mediately drops from the web if she move at his touch.
He finds her position by carefully pulling the lines of
the snare. |
In the theridiids a number of observations have been
described. Menge (1843) found in Linyphia triangularis
that the approaching male shakes the snare rapidly, to
which the female responds by a similar motion. In
Theridium tepidariorum C. Koch I have seen (1903) the
approach of the sexes many times; when a male is placed
upon a web of the female, she immediately signals to
him by repeated jerks upon the lines of the web, some-
times moving towards him. This signalling is a sign
of eagerness on her part, and ‘‘she makes it at no other
time than when she is eager and notices the approach of
a male of her own species. ... The whole attitude of
the male is that of combined timidity and great eager-
ness. . . . He tests the eagerness of the female, and
finds her position upon the web, by grasping with the
claws of his first pair of feet the web lines that she is
158 THE AMERICAN NATURALIST [Vou. XLIV
shaking by her signalling, and by drawing these web
lines taut he feels her movements all the more distinctly ;
he approaches gradually nearer her, guided by her
signalling, and finally makes a short rush toward her.’’
The female often seems insatiable, even leaving food at
times to approach the male, and the courtship is largely
on her part, by signalling.
Similar signalling by the female was noticed by me
in Teutana triangulosa Wolck. During the past summer
I watched the process in Theridium frondeum Htz., where
the female signals, and the male responds in the same
way ; the female had her rear turned towards him so that
she could not possibly see him; in one case a female
signalled to another female. In the case of the tiny
Ceratinopsis interpres Emert. I placed two males and
a female together in a vial, where they spun a maze of
lines in a short time, but I observed quite a different
approach of the males. The female does not appear to
signal, but the male makes a quick rush at her, and taps
her rapidly with his legs until she becomes submissive
with contracted legs. A male acts towards her as he
would to another male, seemingly aggressive, until she
becomes immobile; they find one another by touch com-
municated along the web lines, not by sight.
In the Epeirids a number of genera have been studied.
In Pachygnatha listeri Menge (1866) saw the male seize
with his chelicera those of the female. In Argiope (Peck-
ham 1889, McCook 1890, Emerton 1883) the male courts
the female by pulling the radii of her snare, and she
responds in the same way. ‘‘If matters be favorable,
the male draws nearer, usually by short approaches, re-
newing the signals at the bolting places. Sometimes
this preliminary stay is brief; sometimes it is greatly
prolonged’’ (McCook). In the case of Acrosoma gracile
Walck. I dropped (1903) a male upon the web of a female,
and as soon as he touched her (within five minutes) he
copulated; no special courtship was seen. In the genus
Epeira the approaches of the male are well known from
No. 519] THE COURTSHIP OF ARANEADS - 159
the observations of Walckenaer (1837), Menge (1843,
1866), Termeyer (1866), Lendl (1886), MeCook (1890)
and myself (1903, 1908b). The male approaches the
female cautiously upon her web, locating her and testing
her eagerness by pulls upon a radius, she responding
gently to his signals when she is eager, otherwise she
makes a sudden rush at him in which ease he swings
free from her web on a particular line of his own.
When we sum up what is known of snare-weavers, it
appears that in them sex-recognition is always by touch,
by tapping or pulling of the web. In a few cases
(Tegenaria, Ceratinopsis and perhaps Dictyna) the
male attempts to capture the female by storm; but more
generally he approaches very cautiously and timidly,
signalling to the female. When there is a courtship it
is one of line signals, and sometimes (Theridium) the
female seems the more eager and active in the courtship.
2. Hunters
For the drassids, most of which are nest makers and
essentially nocturnal, there are the following observa-
tions. Menge (1872) placed together a male and female
of Melanophora nocturna, whereupon the male immedi-
ately embraced the female without courtship; and he-
observed (1873) a similar forcible rape in Chiracanthium
oncognathum. In Clubiana trivialis he found (1873) that
the male makes a small saccular nest next that of the
female, and that he knocks, sometimes for days, upon
her nest wall before she allows him to enter. During
the past summer the following observations were made
by me. In Drassus neglectus (Keys.) an adult male
appropriates an immature female, seals her in a mating
nest, and mates with her just after her last moult; in
one case the male found the female in the cage by touch
alone (I could see no evidence of recognition by sight),
and rendered her passive by gentle tapping with his
first legs. The male of Chiracanthium inclusum Htz.
also finds the female by touch, and tries to subjugate her
160 THE AMERICAN NATURALIST [Vou. XLIV
by gentle tapping with his exceedingly long first leg pair.
In Prosthesima atra (Htz.) the male appropriates imma-
ture females; there is no courtship, beyond a tapping
with the legs. The two sexes of Geotrecha crocata
(Keys.) do not recognize each other by sight; a mating
was observed, but no courtship preceded it. Also indi-
viduals of Geotrecha pinnata Emert, do not recognize |
one another by sight, perceiving each other only when
nearly in contact—so probably by air pressure (touch) ;
they run rapidly, and in the open on overcast after-
noons, so they might be expected to form visual images,
but they showed no signs of recognizing each other by
sight. After a mating the male always leaves the female
for a few moments, then returns to her again, and at
such times he moves in an irregular path, feeling for
her. He recognizes her by contact, and taps her legs
with his own until she becomes quiet. In one case a
female accepted in succession and repeatedly the em-
braces of two different males, one of which had only a
single palpus; here the female exhibited no choice what-
soever. In the drassids, accordingly, sex recognition is
wholly by touch; the male sometimes seizes the female
by storm, sometimes subjugates her by tapping with
his legs.
In the thomisids we have to do with diurnal spiders
that lie in wait for their prey, without constructing web
lines (except drop lines); they are mostly found upon
vegetation above the ground. The male is more nimble
than the female and smaller, sometimes much smaller.
In Micrommata virescens Menge (1874) saw the male
jump upon the back of the female. In Xysticus stom-
achosus Keys. I found (1903) that the sexes recognize
each other by sight to some extent, but that the male
pays no particular attention to the female until he
touches her, when he quickly seizes one of her fore feet
with one of his and nimbly swings around and mounts
her from the rear. Last summer I saw somewhat similar
behavior in X. nervosus Banks: the male seemed to
No. 519] THE COURTSHIP OF ARANEADS 161
recognize the female only by touch, when he came in
contact with her he immediately placed several of his
feet upon her, she drew her legs close to her side and he
got upon her dorsum. Also in Misumena aleatoria I saw,
on several occasions, that the minute male always found
the female by touch, and quickly climbed upon her. In
this family, accordingly, even though diurnal, there is
no courtship and the male gains the female by superior
agility aided by his smaller size.
The lycosids comprise crepuscular and nocturnal
species, few of them hunting in the sunlight. Menge
(1877) observed a female of Trochosa terricola Thor.
build a nest in moss, and a male lying for hours before
this hole ‘‘striking lightly here and there with the palps
and fore legs,’’ after which the female allowed him to
embrace her. A similar courtship was seen by Mrs.
Treat (1879) in another lycosid, the species not positively
identified; the female lives in a silken burrow which the
male approaches very cautiously; she ‘‘slowly advances
to meet him, and he slowly retreats from the mouth of
the den, moving backward while she moves forward,
just reaching him with the tips of her fore legs as if
caressing him’’; this backward and forward progression
of the two is repeated many times. Observations on
other lyeosids have been made by me (1903). In
Lycosa bilineata (Em.) (L. ocreata pulchra Montg.) the
anterior male tibie are provided with thick brushes of
vertical hairs, making them very conspicuous, but though
the sexes recognize each other by sight there is no court-
ship; in one case a male simply jumped upon the female,
in another after touching the female the male withdrew
a little and quivered these legs slightly, the female moved
towards him and he jumped upon her.
When the male stands before the female with these legs flexed, as he
does, with the patella close to the sides of his cephalothorax and his
body crouched near the ground, the tibiæ are more horizontal than in-
_ clined upward. This, then, is not the best attitude to exhibit them to
the female. . . . On this account this bristling of the tibie ean hardly
162 THE AMERICAN NATURALIST (VoL. XLIV
be regarded as a sexual ornament that is exhibited to charm the female.
_ Further, it may be noted that this position of the first pair of legs is
also assumed by the female when roughly handled or frightened; it is
an attitude of defense of the species, not of sexual exhibition.
In Lycosa ocreata Hentz (L. stonei Montg.) the tibiæ
of the first legs of the male are similarly provided with
a brush of hairs, and he is darker than the female, but
there is a pronounced courtship by the male consisting
of rhythmically repeated waving of these legs with a
jerking of the whole body backward and forward. Sight
plays a considerable part in the approach of the sexes,
but ‘‘apparently the first recognition of sex is by touch’’
for the courtship does not commence until the male has
touched the female. In L. lepida (Keys.) the male is
smaller and more brightly colored, and exhibits a simple
courtship, shaking in the air his fore-legs that are only
slightly elevated above the ground (his body may be
prone). In L. scutulata Hentz there is ‘‘a decided court-
ship; the male differs from the female in his smaller
size and in the black color of a portion of his fore-legs,
and these legs (and the palpi also) are moved in a par-
ticular manner during the courtship. Observation shows
that the male recognizes the female as such at a distance
of at least six inches. The male’s approach to the female
is very slow, a kind of creeping, not at all similar to the
vehement approach of certain other Lycosids. . . . The
female, if eager, gives the signal of willingness to the
male by touching him lightly with her first pair of legs,
when he immediately embraces. In the observed cases,
with one exception, the female killed the male at the end.
of the copulation.” In Pardosa nigropalpis Emerton the
males are smaller, and there ‘‘is a marked sexual color
difference, the male being deep black and the female
more brownish. . . . The advances are made by the
male, and there is a distinct courtship process, which a
vigorous male may maintain for two or three hours at
a time with few interruptions when the female is recal-
citrant. . . . The courtship motions are as follows:
os
No. 519] THE COURTSHIP OF ARANEADS 163
The male stands with his body well elevated above the
ground (an attitude that the female takes only when she
is aggressive) on his three posterior pairs of legs, his
head higher than his abdomen. . . . He waves his palpi
upward in the air (i. e., straightening them out before his
head) and flexes them outward, from one to three times,
then draws his body slightly backward and downward,
rapidly waving in the air the outstretched palpi and first
pair of legs, and spasmodically shaking the whole body
with the violence of the movement... . The male recog-
nizes a female as such immediately on touch; whether he
recognizes her by sight alone I can not tell. In courting a
fleeing female the male appears to follow her mainly by
sight,’’ but only when she is moving. In lycosids, accord-
ingly, there is no courtship or else a complicated one; sex
recognition is by touch alone, or by touch and sight com-
bined.
For the attids we have a considerable number of ob-
servations. Seidel (1847) states that at the time of mat-
ing several females of Salticus-scenicus Hahn seek out
one male and live with him. But the greater part of our
knowledge on this group is due to the Peckhams. In
1889 they described the courtship of Saitis, Epiblemum,
Icius, Hasarius, Synageles, Marptusa, Phidippus, Den-
dryphantes, Zygoballus, Habrocestrum, Philaeus and
Astia, with full delineations, accompanied by excellent
drawings, of the posturings and movements of the male,
which in some species are the most complex yet known.
There are peculiar jumping and wheeling movements
constituting dances, besides erection and display of those
parts of the body that are strikingly colored and modified.
We have not space here to repeat their descriptions and
could not, indeed, do justice to them in a short summary;
the reader should refer to the original memoir. In a
following paper (1890) these authors describe the court-
ship of Habrocestrum, which is peculiar in that a male
exhibits an ornamentation of the third pair of legs, and
they give new figures of the attitudes of Synageles picata.
164 THE AMERICAN NATURALIST [ Vou. XLIV
In their last study (1909) they figure the male posturings
in Pellenes and Euophrys—in E. monadnock the male
taking such a pose as to display at once the yellow palps,
the heavily bristled, black first leg pairs (held elevated),
and the orange femora of the third and fourth pairs.
Finally, I would add the observations made by me last
summer on a considerable number of pairs of the large
Phidippus purpuratus C. Koch. Here the male is not
much smaller than his mate, but much darker and with
more iridescence. A male will court on sight of a female,
without first touching her; his motions consist of elevation
of the cephalic region, raising and outspreading the first
leg pair (with some waving of them), accompanied with
advance towards the female and retreat from her as well,
as side-stepping. After a male has once courted and won
a mate, if he is kept in the same cage with her, he there-
after courts to much less degree, and finally not at all,
before embracing her; that is, he would seem to have lost
his fear of her, and indeed the pregnant female will more
frequently run away from him than he from her.
IV. INTERPRETATION OF THE COURTSHIP PHENOMENA
Preliminaries to mating, whereby one individual seeks
to gain the favor of another, constitute what we mean
here as courtship. My previous definition (1903) of it,
“a rhythmically repeated set of motions on the part of
the male,’’ was incomplete in limiting the process to one
sex, for the female also may take part. Some mode of
courtship would then occur where there is no immediate
seizure of the female by the male, and where one of the
individuals, generally the male, is the more eager.
In some cases there is no courtship, where the male is as
large or larger than the female, the male seizing the
female—sometimes appropriating her when immature, and
mating with her shortly after her last moult. And in the
thomisids the male captures his mate by superior agility.
But more usually there is some form of courtship, and this
may be by either touch or sight.
No. 519] THE COURTSHIP OF ARANEADS 165
In the case of courtship by touch, the simplest form, in
Drassids, Dictyna and some Agelenids, is that where the
male after recognizing a female by touch taps her rapidly
with his feet until she either runs from him or else be-
comes quiet and submissive to his embrace. The more
complex form is found among the snare-makers, espe-
cially epeirids and theridiids, and the courtship is by
signal pulls upon the lines of the snare; in this way the
male not only locates the position of the female upon her
snare, but he also ascertains whether she is eager for him,
for when she is eager she returns his signals in the same
way.
Courtship by sight is found most highly developed in
the attids, less complicated in the more corpuscular ly-
cosids, but not at all in the diurnal thomisids} it is not,
accordingly, characteristic of all diurnal species. The
courtship movements of the male range from a simple
waving of the first leg pair, or waving of these and the
palpi, to much more complicated movements of these
parts associated with peculiar posturings, advances and
retreats, and side-wheeling.
This brings us to the important question, just what
psychical and physiological elements enter into the court-
ship? We can most clearly discuss this by considering
the sexes in turn. Without question the chief psychical
condition is sexual desire, in the case of the male, result-
ing froma physiological state due to internal secretions at
the time of maturity. But with it is associated an inhib-
iting factor, the male’s fear of the female. When the
male is as strong as the female he exhibits no special fear
of her, she is rather distinctly timorous towards him,
then he does not court but seizes her by force. But in
most species the male is smaller, in some cases very much
smaller, than the female, and in all such instances he
indicates great caution in approaching her, which is a
demonstration of fear on his part. Adult females are
decidedly more pugnacious than males, and contests be-
tween females are generally fatal to one of the contest- _
166 THE AMERICAN NATURALIST [Vou. XLIV
ants, while this is seldom the result in battles between
males. I once saw a male of Phidippus purpuratus kill
his mature mate, and McCook (1890) has listed such
cases in agelenids; but such happenings are very rare,
and occur only when the male is as powerful as the fe-
male. In the great majority of species the male is deci-
dedly afraid of the mature female, at least until after he
has mated with her, and he does not exhibit towards her
those aggressive movements which she often displays
towards him. His embrace need not mollify her, for in
certain epeirids and lycosids she has been seen to kill him
immediately after the mating. It is interesting to note
that one of the most general motions made by the male
in courtship is the raising and extension of the forelegs
towards the female, which is but a modification of a
spider’s general attitude of defense—a motion exhibited
by both sexes when strongly disturbed.
Now there is courtship by the male only when he does
exhibit this fear. Accordingly, we may conclude that
courtship by the male spider results from a combination
of the state of desire for and fear of the female. This
explains satisfactorily why in some cases there is court-
ship while in other cases there is not. Courtship by the
male continues until he has learned that the female is not
hostile towards him; and his successive advance and re-
treat in her direction gives him the opportunity of expe-
riencing, so learning, her degree of aggressiveness. By
this courtship he advertises himself as a male, for no
female shows such movements; and he may at the same
time prominently display his ornamentation.
But we have neither reason to suppose that he is con-
cious of influencing the female thereby, nor that he is
conscious of exhibiting particular personal attractions
towards her. For in those lyeosids where there is little
secondary sexual difference the male may have as com-
plex courtship movements as in cases where he is more
ornamental. And it is assuming too much about a
spider’s mentation to postulate that the male is not only
No. 519] THE COURTSHIP OF ARANEADS 167
conscious of his beauties, which are generally so placed
that he can not perceive them himself, but has also an
idea that he may arouse the female’s esthetic sense. The
Peckhams remark (1890, p. 122):
That whatever fine points of color or structure the male possesses,
his actions before the female display them to the very best advantage;
indeed, he seems to have a strong consciousness of every advantage,
and to sedulously strive to bring it to the notice and impress its beauty
upon the mind of the female to whom he is paying his addresses.
But they add a modifying foot-note:
We do not say that, in our opinion, he is conscious of his strong
points. It is quite conceivable that the tendency to perform the antics
may have developed along with the beauties which they serve to display
without any idea of this existence dawning in the mind of the spider.
I think we should, until we have evidence to the con-
trary, accept as the correct interpretation the suggestion
stated in that last sentence of the Peckhams, 7. e., that
the male is not conscious that he is influencing the femalé,
either sexually or esthetically.
We have just seen that the raising of the forelegs in
courtship is but a modification of the general attitude of
defense, therefore not primarily for. display. The waving
of the palpi may follow any excitement, is also not ex-
clusively sexual. And I have been interested in finding
a partial explanation of a male attitude exhibited by cer-
tain attids, namely the lateral flexion of the abdomen. In
Phidippus purpuratus the male at frequent intervals in
his courtship touches his spinnerets to the ground, thus
attaching a silken line, and then in his side-wheeling be-
fore the female, with closed spinnerets, this line pulls his
abdomen to one side. Such flexion of the abdomen, at
least in this particular species, is thus not a conscious
effort of display, but is due to a simple tension of the
ordinary drag-line.
Last summer I observed in several species the curious
phenomenon of males courting one another in the same
way as they do females. I placed in a small cage two
males of Pardosa pallida, Emert., and they moved their
168 THE AMERICAN NATURALIST [Vou. XLIV
fore-legs and palpi just as in normal courtship. Two
males, a smaller and a larger, of Phidippus purpuratus
were placed together; the larger was aggressive, the
smaller exhibited towards him normal courtship motions.
In neither of these cases were females present. Two
males of the brilliant Phidippus mccooku Peck. on being
placed in one cage, on several different occasions, raised
the legs, side-wheeled, and flexed the abdomen laterally,
resembling a courtship; I had no female of this species
to determine the normal courtship, but to females of
P. clarus Koch they acted in the same way. Two males
of Zygoballus bettint Peck. were placed in a cage and
watched each other attentively, but without courtship;
an immature female was introduced, when each male pro-
ceeded to court her: advancing and retreating by short
quick steps, the first legs raised vertically and parallel
and these and the palpi twitching; the female ran away
from both, and after I had removed her the males ex-
hibited the same movements towards each other, with the
only difference that the raised legs were somewhat di-
vergent and that the smaller male fled when the larger
came too near. Evidently in these cases the males mis-
took one another for females, which would indicate that
their visual discrimination is far from precise—perhaps
less than that of the females.
The female is also actuated by sexual desire, sometimes
quite as strongly as the male; this is the case with Therid-
ium tepidariorum, where the female seems insatiable, and
the Peckhams (1889) observed a female of Saitis pulex
approaching a male with courting movements. In ther-
idiids and epeirids the female signals along the snare
lines quite as vigorously as the male does.
But whenever she is larger than the male, she exhibits
as a rule, no great fear of him. She may express her
desire to the male by remaining quiet and passive, or
by touching him gently or moving towards him, or by
counter-signalling by means of lines of her snare; and
sometimes she may take the initiative in this. Where
No. 519] THE COURTSHIP OF ARANEADS 169
the courtship is by touch it is wholly excluded that the
female can have any esthetic appreciation of the male, she
is actuated either by sexual desire or by its absence. But
where there is courtship by sight, as in the attids and
some lycosids, the Peckhams have consistently maintained
that the female is influenced by an esthetic appreciation
of the colors, ornaments and postures of the male, and
that she chooses that male that pleases her esthetic sense;
and they have reiterated this view in their last paper
(1909) without referring to my quite different interpreta-
tion (1903). Now there is no doubt that, as the Peckhams
have shown, when there is courtship by sight the female
attentively watches the male, and also no doubt that the
male’s motions are generally such as to exhibit his colors
and ornaments to the best advantage; an exception to this
is that the male of Lycosa bilineata exhibits no courtship
although his fore-legs are provided with thick brushes
of hairs. Then there is the interesting observation (Peck-
ham, 1889) that of the two male forms of Astia vittata
the female always selects the more ornamented niger-va-
riety, which is darker and possesses plumose tufts on the
cephalothorax, though it is not stated in how many cases
this was observed. But it is significant that the niger-
form ‘‘is much the more lively form of the two’’; it might
then be the case that the female selects him not because
he is more ornamented, but because he is more lively,—
therefore because he more quickly advertises himself as
amale. This seems to me to be the correct understanding
of the matter. For just as we have no evidence that the
male consciously endeavors to exhibit his attractions, we
have also no evidence that the female is influenced esthe-
tically. What we do know is that the male by his court-
ship, a set of motions resulting from the conflicting states
of sexual desire and fear, exhibits or advertises himself
as a male; and that the female on sight of this courtship
recognizes him as a male and accepts him if she be eager,
or else becomes gradually stimulated by watching him.
In other words, too great an assumption is made in sup-
posing the female to have an esthetic sense, while it is
170 _ THE AMERICAN NATURALIST — [Vou. XLIV
more probable that the female is attracted by maleness
alone and not by beauty. The immediate effect of court-
ship on the female is the stimulation of her sexual desire
by recognition of a male, not first the arousing of an
esthetic sense and second the arousing of sexual feelings.
On my interpretation the case in Astia may be explained
simply and without assumption: the niger-form is se-
lected by the female because he is more different in color
and structure from her than is the other male form, con-
sequently is more quickly recognized as a male; this is
what determines her, and not color or ornaments. The
significance of peculiarities in color, structure and move-
ments of the male lies in insuring quick sex-recognition,
not in arousing esthetic feelings. The case of Astia is
the only one known in which the female seems to exert a
choice between males, dimorphism of males being rare in
spiders.
We conclude, accordingly, that the male in visual court-
ship is not actuated by a conscious effort to exhibit his
peculiar beauties, and that the female does not select
males by an esthetic sense. Courtship by the male re-
sults simply because fear is mingled with his desire; and
probably the female will accept the first male who courts
her, and makes himself recognized as a male, at the time
when she is physiologically desirous. Sexual selection
in the meaning of Darwin, accordingly, and in opposition
to the views of the Peckhams, has probably played no part
in the evolution of the secondary sexual differences of
spiders. .
V. Tue NATURE AND USE OF THE SECONDARY SEXUAL
DIFFERENCES
We are not concerned here with the question of the first
origin of secondary sexual differences, i. e., whether they
have arisen as gradual fluctuations, as Darwin held for
the most part, or from acquired traits becoming inherited
on the view of Cunningham (1900), or from sudden mu-
tations as Morgan (1903) has suggested, for there is no
observational evidence from which we can reason. We
No.519] THE COURTSHIP OF ARANEADS 171
have rather to consider their value to the species, what is
their use, and the factors which have served to perpetuate
them.
In the first place it will be convenient to name categor-
ically the main classes of secondary sexual characters
found in animals in general, and second to discuss the
significance of those found in araneads.
Plate (1908) has furnished a useful tabulation of sec-
ondary sexual characters, devised mainly to show ‘‘what
an enormous morphological field is comprised in this
term.” The following arrangement of such characters is
simpler than his, though as comprehensive, and will be
more convenient for our present discussion.
1. Weapons employed by males in their combats with
one another.
2. Characters used for sexual recognition and sexual
stimulation.
3. Characters of more immediate value in ensuring
approximation of the sexes and copulation.
4, Characters of value in provision for and nurture of
the progeny.
5. Characters due to habitudinal differences of the
sexes.
6. Characters of value in protecting a particular sex
against other species.
We may next determine how these six main groups of
characters are represented in spiders.
1. The weapons employed by males in their fighting for
the possession of females are readily explained, as Darwin
did in the first part of his theory of sexual selection, as
being perpetuated by a natural selection between males.
Such direct combats between males do not appear to
occur among spiders, neither do the males possess pecul-
iar weapons, unless peculiarly modified chelicera may be
considered as weapons. Mature males when placed to-
gether will frequently fight, but the Peckhams (1889) in
describing this in the case of an Icius conclude that the
battles are probably sham affairs, rarely resulting disas-
trously, and ‘‘gotten up for the purpose of displaying
172 THE AMERICAN NATURALIST [Vou. XLIV
before the females.” There may be more fighting be-
tween males when females are present, though there is no
good evidence on this matter; but we have no reason to
suppose that the males consciously endeavor to exhibit
their prowess any more than they consciously try to dis-
play their ornaments. Males of the attid Icius palmarum
placed in small cages were not observed by me to fight,
nor were males of Phidippus mccooki nor those of Zygo-
ballus bettini; but fighting of males was noticed in Cera-
tinopsis interpres, Geotrecha pinnata and Xysticus nerv-
osus, and in the last species a male would leave the back
of a female to fight a rival. But, as the Peckhams found,
no injuries result to the males from this fighting, there-
fore these are not serious combats, and only once have I
seen a male kill another male of his species (in Pros-
thesima atra).
Male spiders also do not possess intimidation organs,
which result when weapons become hypertrophied accord-
ing to the views of Guenther (1909).
2. Characters for sexual recognition and stimulation
may be subdivided according to the sense organs which
they affect, as Jäger (1874) has indicated. As we have
seen, the only senses concerned in the case of spiders seem
to be those of touch and sight. It may be that certain
of the tactile organs, probably certain of the jointed
spines, may become more numerous or more specialized
at maturity to aid in sexual recognition, but this point re-
mains to be tested. But those secondary sexual charac-
ters of male spiders found only where there is courtship
by sight, such as ornamental colors and structures, and
posturings that display them, fall under this category.
Such are the male differences, as the Peckhams have
shown, in the chelicera, clypeus, palpi and legs, that is,
‘‘in those parts of the animal that are plainly in view
when the male is paying court to the female.’’ Thus the
chelicera may be lengthened, curved or spinous; the
ciypeus may be heightened or bear prominences; the first
pair of legs may be thickened or have tufts of hairs; and
any or all of these parts may have conspicuous color
No. 519] THE COURTSHIP OF ARANEADS AS gs
markings. These differences are so pronounced in the
attids that in many cases the species is known only by .
one of the sexes. We have previously seen that conscious
esthetic choice by the female probably does not account
for such male characters, that they are, accordingly,
probably not due to sexual selection. These characters
of the males may be most readily explained as being con-
served by simple natural selection. Peculiar male orna-
mentation would be selected because it insures quicker
sex-recognition, therefore prompter mating. The male is
thereby more surely accepted by the female, not selected
by her in the sense of Darwin. The process is much
more an announcement of sex by the male than a choice by
the female, and results in the female accepting the sex
rather than the individual. There is no reason to sup-
pose the female spider is actuated esthetically, while we
do know she is actuated sexually—in some cases quite as
much as the male is. There is no need of calling in any
other factor than natural selection.
Whether such ornamental male characters, which stim-
ulate the visual sense of the female, subserve sex recog-
nition rather than sex stimulation we are hardly able to
decide in the absence of any thorough analysis of the
psychical states of spiders. But probably a female would
first have to recognize a male as a male before she became
sexually aroused by him, and for this reason male orna-
mentation would seem to be primarily to insure sex-recog-
nition rather than sex-stimulation.
In opposition to the views of Wallace (1889) the Peck-
hams (1890) have correctly argued that the ornamentation
of male spiders is not due to any ‘‘ higher degree of vital-
ity’? of the males, for the female seems to be in all re-
spects fully as active as the male, and at maturity even
more active. The same objection may be made against
the concept of Geddes and Thomson (1897) with regard to
differences of the sexes.
The Peckhams have found in the attids, in agreement
with Darwin’s conclusions for birds, that: (a) when the
adult male is more conspicuous than the adult female, the
174 THE AMERICAN NATURALIST [Vou. XLIV
young of both sexes more closely resemble the- adult
female; (b) when the adult female is more conspicuous
than the adult male, the young of both sexes more closely
resemble the adult male; and (c) when both adults are
alike the young of both sexes resemble them.
3. Characters of value after the act of sex-recognition
to insure efficient mating would seem to be various, and all
probably perpetuated by natural selection. Such would
be the relatively larger legs in the case of certain males,
in so far as they serve to hold the female. Smaller size
and greater agility of the male, not a frequent phenom-
enon in araneads, would also aid in the mating by ena-
bling the male to move more quickly upon the snare of the
female, and to escape more rapidly from her should she
be aggressive.
4, Characters of value in providing for and nurturing
the young are limited in spiders to the female, and are
also perpetuated by natural selection. Such are the
greater size of the abdomen to accommodate the eggs, and
the gland whose function is to agglutinate them. Such is
also the greater pugnacity and bravery of the female,
which is probably the expression of her greater need of
food. i
5. Characters due to habitudinal sex differences are
few in spiders. Such differences first become marked at
maturity, as do the other secondary sexual characters,
all being in some way connected with internal secretions
formed during the elaboration of the genital products.
In the epeirids, as shown by me (1908b), immature males
have the same mode of life as their sisters, and ‘‘construct
nerfect snares of the types of those of their respective
females. But the adult males . . . do not spin snares at
all, but build nests near those of adult females.’’ Indeed,
it is quite general among snare-making species that adult
eager males regularly leave their snares to live upon or
near those of females; and adult males of lycosids and
drassids, which make no snares, leave their nests to seek
for females. The chief habitudinal difference, accord-
ingly, is that while the female continues a more or less
No. 519] THE COURTSHIP OF ARANEADS 175
sedentary existence, or makes excursions mainly for food,
the male in many species becomes a wanderer when he is
adult, searching for a mate. The male thus comes to
spin less and to run more; and a morphological conse-
quence of this habit is seen in the total or nearly complete
loss of the cribellum, or spinning plate, by adult males
of certain species. It is possible his relatively greater leg
length may be in some cases also associated with this
habit. These few cases would fall in line with the theory
of Cunningham (1900), being characters due to difference
in mode of life of the sexes. But all such phenomena
would be likewise regulated by natural selection.
6. The secondary sexual characters which operate to
protect a particular sex in the struggle for existence are
found mostly in the females, and these would be subserv-
ient to natural selection. In certain spiders, as notably
some epeirids (Argiope, Acrosoma, Gasteracantha), the
female is not only much larger than the male, but also much
more brightly colored, often with most conspicuous black
and yellow or red and yellow markings; and in Acrosoma
and Gasteracantha the abdomen may be drawn out into
angular processes and spines. We can not accept for this
case the Peckhams’ suggestion that this is due to differ-
ence of mode of life of the sexes, for so far as is known
the males of these have the same mode of life as those of
other epeirids. These brilliant and remarkable females
all build their snares in the open sunshine, and remain
upon the centers of the snares. They would seem rather
to represent cases of warning coloration, this ultimately
protective to the possessors: in Acrosoma and Gastera-
cantha the bright markings would serve to advertise the
hard and spinous abdomina, and in Argiope, which is
soft-bellied, perhaps to announce the large snare. Pos-
sibly the brushes of hairs on the legs of another female
epeirid, Nephila, would be an example of warning char-
acters calling attention to the unusually large and power-
ful web, thus protecting the snare against birds. It is
always difficult to be sure of a correct interpretation of
phenomena of this kind, but it would seem probable
176 THE AMERICAN NATURALIST [Vowu. XLIV
that some cases of brighter female coloration represent
examples of warning coloration, and consequently come
under our sixth category of secondary sexual phenomena.
It will be recalled that Wallace (1889) explained the
general less conspicuous coloration of female birds on
the ground of their need of greater protection, since they
play the major rôle in guarding the nest and the eggs.
The Peckhams (1889) have argued that this idea would
not apply to the general inconspicuous coloration of
female attids, because when they have eggs they hide
these and themselves within thick silken nests and so are
sufficiently protected from enemies. But I believe Wal-
lace’s explanation will apply in the case of spiders. For
the males do not develop their ornamentation until matu-
rity, and they have much less need of protection than the
females because they live usually not much longer than
a few weeks after maturing, and take no part in the care
of the young. ,The males have fulfilled their main func-
tion after impregnating the females, and they are of no
use to the species thereafter. But the females live at least
several months after maturing, in some cases several
years, and they have the whole care of the eggs and young.
In araneads, as in all animals, the females are of the
greater importance in the perpetuation of the race.
Therefore it is probable, in agreement with Wallace, that
natural selection has generally maintained a more pro-
tective coloration of the female.
In all six categories of secondary sexual characters in
so far as spiders are concerned, accordingly, natural
selection alone is sufficient to explain the regulation of the
phenomena. At the same time these phenomena would
seem to have a manifold origin, as they certainly fulfill
very different uses.
LITERATURE LIST.
1873. Canestrini. Caratteri sessuali — degli Arachnidi. Atti Soe.
Veneto-Trentina Se. Nat. Padova
1900. Cunningham, J. T. Sexual bathe ee in the Animal Kingdom.
London.
1886. Darwin, C. The Descent of Man, and Selection in Relation to Sex.
New ed., New York
No. 519] THE COURTSHIP OF ARANEADS ig it
1908b.
1903.
1889.
Emerton, J. H. The Structure and Habits of Spiders. Salem.
Geddes, P., and Thomson, J. A. The Evolution of Sex. London.
Guenther, K. Der Kampf um das Weib in Tier- und Menschenent-
wicklung. Stuttgart.
Tiger, G. In Sachen Darwins. Stuttgar
Lendl. Ueber die Begattung und die ro e BE von Tro-
Motsch.
chosa infernalis Term. Füzetek. Budapest,
McCook, H. ©. American Spiders and their Spinning bak Vol. II.
Philadelphi
Menge, A. ais die Lebensweise der Arachniden. Neueste Schr.
naturf. Ges. Danzig, 4
Menge, A. Preussische Spinnen. I. Schr. naturf. Ges. Danzig
Che 2); L
Menge, A. Idem, 5. Thid., 3.
z
Montgomery, T. H. Studies on the Habits of Spiders, particularly
A Nat
those of the Mating Period. Proc. Acad. . Sci. Philadelphia.
Montgomery, T. H. The Sex Ratio and ae Habits of an
Aranead, and the Genesis of Sex Ratios. ool. 5.
Jour. Exper
Montgomery, ee H. Further Studies on the pis of APA
AMER. NAT
organ T. H. Pae ata and pa n. New York.
Peckham, G. W. and E. G. Observations on, Sexual Selection in
Spiders of the Family Attidae. Goti Papers Nat. Hist. Soe
Wisconsin, 1.
Peckham, G. W. and E. G. Additional s on Sexual
Selection in Spiders of the Family Attide. Ibid.,
Peckham, G. W. and E. G. ee of the Attide 4 North Amer-
ica. Trans. Wisconsin Ac
Peara, A. Studies in Kdapiation 1. The Sense of Sight in
Spiders. Journ. Exper. Zool.,
Plate, L. aiana aa “Probleme der Artbildung. 3te
Ausg., Leipzig.
Pritchett, A. H. Observations on Hearing and Smell in Spiders.
AMER. N
AT., 38.
Seidel. Einige Beobachtungen an Spinnen. Uebersicht Arbeit.
Veränd. Schles. Ges. väterl. Kultur, Breslau.
Termeyer, R. M. de. Researches and Experiments upon Silk from
Spiders, and upon their Reproduction. Transl. by B. G. Wilder.
Proc. Essex Inst., 5.
Treat, M. The Habits of a Tarantula. AMER. Nar., 13.
Wagner, W. a OE nommés auditifs chez les Araignées. Bull.
Soc. Nat. M
peagi Histoire Naturelle des Inséctes, Aptères. Suites à
on,
tines ke R. pe rwinism. London.
Westring, N. Araneæ Suecice deseripte. Gothoburgi.
NOTES AND LITERATURE
NOTES ON ICHTHYOLOGY
One of the most important publications in ichthyology, as a
result of the stimulus given to zoology by our knowledge of
evolution, is the ‘‘Cave Vertebrates of America,” by Dr. Carl
H. Eigenmann, of the University of Indiana, published by the
Carnegie Institution of Washington. In this large and finely
printed volume is a complete discussion of caves and of cave
fauna, the greater part of this fauna being composed of blind
fishes. The caves of Indiana, Kentucky, Missouri and Cuba
have been especially investigated in this paper. Dr. Eigenmann
shows very conclusively that those species of fishes which are
the ancestors of the blind forms were of those types which avoid
the light, skulking in darkness in preference. Those fishes
which take their prey by sight alone are never represented
among the ancestors of cave fishes. Dr. Eigenmann adopts the
judgment, independently reached by Mr. Garman, that the
originals of the cave species (non-aquatic, especially) of Ken-
tucky were probably already adjusted to a life in the earth
before the caves were formed. Dr. Eigenmann concludes:
1. That the eave fauna is in large part the result of this forma-
tion of the caves themselves, that environment and habitat de-
veloped pari passu.
2. That to this original fauna have been added and are being
added species (such as Spelerpes maculicauda) which, because
they are negatively heliotropic or positively stereotropic, are
gradually becoming adapted to the deeper and deeper recesses
of caves.
3. That to the fauna of the larger caves may also have been
added animals which had become adjusted to cave existence in
erevices, under banks or rocks, ete., that is, in small caves.
4. That accident has played little or no part in developing
the cave fauna.
As to the general cause of degeneration, Dr. Eigenmann is
inclined to take the Lamarckian view, involving the inheritance
of results of disuse. A number of species of blind lizards are
discussed, as well as certain blind fishes which are not found in
caves. Among these are the parasitic hag fishes, Polistotrema
stouti, of the coast of California, and the blind goby of Point
Loma, in California, Typhlogobius, which lives in the darkness
178
No. 519] NOTES AND LITERATURE 179
on the under side of shelving rocks. There ‘is also a blind cat-
fish, Ameiurus nigrilabris, which is found in caves of Lancaster
County, Pennsylvania.
The best known of the blind fishes belong to the family of
Amblyopsidz. The genus, Chologaster, contains one species with
eyes, inhabiting the channels about the Dismal Swamp and the
rice canals of the South. The other species are known only
from caves and cave springs, and all the representatives of the
genera, Amblyopsis, Troglichthys and Typhlichthys, are blind.
Dr. Eigenmann has also made an elaborate study of the blind
fishes of Cuba, Lucifuga subterranea and Stygicola dentatus.
These two fishes belong to the family of Brotulidex, a relative of
the blennies. The origin of these forms is from marine fishes
living in clefts of coral rock. This coral rock, when raised
above the sea, seems to have carried these forms with it. e
nearest related genus, Brosmophycis, still lives among the corals.
The details of anatomy, as well as the details of environment,
of each of these species, are very fully illustrated in this paper,
which is by far the most important one yet devoted to this
subject.
Dr. Eigenmann observes in conclusion that it is absolutely
certain that the caves were*not peopled by a catastrophe, and,
further:
That the cessation of use was gradual and the cessation of selection
must also have been a gradual process. There must have been ever
widening bounds within which the variation of the eye would not
subject the possessor to elimination.
Chologaster is in a stage of panmixia as far as the eye is concerned.
It is true the eye is still functional, but that the fish can do without
its use is evident by its general habit and by the fact that it sometimes
lives in caves.
The present conditions have apparently existed for many genera-
tions, as long as the present habits have existed, and yet the eye still
maintains a higher degree of structure than reversed selection, if oper-
- ative, would lead us to expect, and a lower degree than the birth mean
of fishes depending on their eyes—the condition that the state of
panmixia alone would lead us to expect. There is a staying quality
about the eye with the degeneration, and this can only be explained
by the degree of use to which the eye is subjected.
The results in Chologaster are due to panmixia and the limited
degree of use to which the eye is put. Chologaster agassizii shows the
rapid diminution of the eye with total disuse.
The difference in the conditions between Chologaster and Ambly-
opsis, Typhlichthys and Troglichthys is that in the former the eyes
180 THE AMERICAN NATURALIST [Vor. XLIV
are still in use, except when living in caves; in the latter they have not
been in a position to be used for hundreds of generations. The transi-
tion between conditions of possible use and absolute disuse may have
been rapid with each individual after permanently entering a cave.
Panmixia, as regards the minute eye, continued. Reversed selection
` was inoperative, for economy ean not have affected the eye for reasons
already stated. Simply the loss of the force of heredity, unless this
was caused by disuse or the process of germinal selection, can not have
brought about the conditions, because some parts have been affected
more than others.
Considering the parts most affected and the parts least affected, the
degree of use is the only cause capable of explaining the conditions.
Those parts most active during use are the ones reduced most, viz.,
the muscles, the retina, optic nerve and dioptrie appliances, the lens
and vitreous parts. Those organs occupying a-more passive position,
the scleral cartilages, have been much less affected and the bony orbit
least. The lens is one of the latest organs affected, and not at all
during use, possibly because during use it would continually be in use.
It disappears most rapidly after the beginning of absolute disuse
both ontogenetically and phylogenetically. Al indications point to use
and ant as the effective agent in molding the eye. The process does
not, however, give results with mathematical precision. In Typh-
lichthys es the pigmented layer is affected differently from
that of Amblyopsis. The variable devélopment of the eye muscles in
different species would offer another objection if we did not know of
the variable condition of these structures in different individuals.
Chilton has objected to the application of the Lamarckian factor to
explain degeneration on account of the variable effects of degeneration
in various invertebrates. But such differences in the reaction are still.
less explicable by any of the other theories.
In the Biological Bulletin for January, 1905, Professor Eigen-
mann describes two species of blind fishes, Typhlichthys osborni,
from Horse Cave, Kentucky, and Typhlichthys wyandotte, from
Corydon, Indiana, near the large Wyandotte Cave.
In the Field Columbian Museum, February, 1909, Dr. Seth
E. Meek describes a number of species from Tropical America.
These are: Rhamdia nasuta, from Buenos Aires de Terraba,
Costa Rica; Astyanax regani, from Las Cañas, Costa Rica;
Cyprinodon dearborni, from Willemstad, Curacao, Dutch West
Indies; Girardinus vandepolli, from Curacao; Pæcilia caudata,
from Turrubares, Costa Rica; Cichlasoma punctatum, from
Buenos Aires de Terraba, Costa Rica; and Cichlasoma frontale,
from Turrubares, Costa Rica.
In the Proceedings of the Zoological Society of London, 1909,
No. 519] NOTES AND LITERATURE 181
Mr. Regan describes a collection of fishes from Christmas Island,
Six species being new.
In the same Proceedings, 1909, Mr. Regan gives an interesting
account of the changes in coloration in living fishes, as observed
in the New York Aquarium. The same subject has been since
much more fully treated by Charles H. Townsend, director of
the aquarium.
In the Annals and Magazine of Natural History, 1909, Mr.
Regan gives the name Orectolobus ogilbyi to the species from
Torres Straits which Ogilby and McCulloch had identified with
Orectolobus dasypogon. Mr. Regan admits that Eucrossorhinus,
established by him for dasypogon, is not distinct from Orecto-
lobus.
In a publication of the Station at Boulogne-sur-mer, Dr. H.
E. Sauvage gives a comparative study of the peritoneum of
flounders.
In the Bulletin de la Société Belge de Géologie, 1908, Mr.
Maurice Leriche discusses new species of fishes from the Oli-
gocene of Belgium.
In the Annales de la Société Géologique du Nord, Volume 37,
1908, at Lille, Mr. Maurice Leriche discusses the fossil sharks
of California, with special reference to the papers of Agassiz
and Jordan. Leriche regards these American species as identi-
eal with the nearest corresponding species of Europe. It is a
matter in which certainty is not often possible. Most of the
living species now found on the Pacifie Coast are different from
the corresponding living sharks of Europe, but this is appar-
ently not true in every case, and in most cases the teeth do not
show adequate differences. It is also not possible in every case
to know whether different teeth represent really different species,
or whether they may be from different parts of the mouth of
the same animal. Heptranchias andersoni, from California, is
identified with Notidanus primigenius, of Agassiz. It may be
here noted that Heptranchias of Rafinesque is much the older of
the two generic names concerned. Lamna clavata, of Agassiz, is
identified with the European Lamna cuspidata, of Agassiz.
Mr. Leriche states that in another paper he will show that this
species belongs to Odontaspis, and not to Lamna. Mr. Leriche
regards Isurus planus, I. tumulus of Agassiz, and I. smithii of
Jordan, as identical. Planus, according to Leriche, represents
the upper teeth, and tumulus the lower teeth, while smithii is
the name of the front teeth of young specimens. It is not un-
182 THE AMERICAN NATURALIST [Vou. XLIV
likely that this view of the case is the correct one. We may
notice, however, that Rafinesque’s name Isurus is much older
than Oxyrhina. Carcharodon rectus, of Agassiz, and C. bran-
neri, of Jordan, are regarded as identical with C. megalodon,
the giant shark of the Miocene fossil beds about the Atlantic.
C. arnoldi, of Jordan, and C. riversi, of Jordan, Leriche regards
as identical with the living C. rondeleti, for which the older
name is C. carcharias. This may possibly be true of the riversi,
but the arnoldi is based on a specimen far larger than that of
the largest living man-eating shark, C. carcharias. Hemipristis
heteropleurus, of Agassiz, is regarded as identical with the
European Hemipristis serra. This identity was also indicated
by Dr. Jordan. Galeocerdo productus, Agassiz, is regarded as
identical with G. aduncus, Agassiz. Among the unidentified
teeth photographed in Jordan’s paper, Leriche recognizes
Aprionodon, Galeus and Squatina.
Leriche also notes that these observations show the great
geographical extension of the species of sharks, and the im-
portance that these have in the establishment of synchronisms
at great distances. It is, however, true that specific differences
of many kinds exist in species of shark, without showing them-
selves in the teeth. It is, however, safe to recognize no species
as now known by the teeth alone, unless the teeth show tangible
differences.
In the same annals Leriche describes numerous sharks and
other fishes from the early Tertiary about Rheims.
In the same annals Leriche describes the teeth of various
earboniferous fishes of the north of France and of Belgium.
- In Science, May 28, 1909, Mr. Barton A. Bean shows that the
name of the American eel should be Anguilla rostrata (Le
Sueur), this name being earlier than that of chrisypa given by
Rafinesque at about the same time.
In the Bulletin of the American Museum of Natural History,
Volume 26, 1909, Dr. L. Hussakof describes a new species of
the extraordinary genus of goblin sharks, of which the living
form is known as Mitsukurina, and the extinet species by the
earlier name of Scapanorhynchus. Dr. Hussakof gives to this
new species the name of Scapanorhynchus jordani. In this
species, the long blade of the snout is longer than in S. owstoni;
the eye is further forward, the gills are smaller, and there are
other differences of importance. Dr. Hussakof has no doubt
that Mitsukurina is identical with the Cretaceous Scapano-
No. 519] NOTES AND LITERATURE 183
rhynchus, as indicated by Dr. Woodward. The differences be-
tween these living and fossil species are no greater than the
differences among the species of the genus itself. Dr. Hussakof
agrees with Jordan that Scapanorhynchus is closely related to
the Odontaspid sharks, but whether it should be placed in that
family or constitute a distinct family must depend on further
studies of its anatomy.
One of the most remarkable features in geographical distribu-
tion is the extraordinary number of singular animals, especially
sharks and chimeras, which have been discovered in the waters
of Sagami Bay, the first bay to the southward of Tokyo in Japan.
In the Mark Anniversary Volume Dr. Jacob Reighard de-
scribes in great detail the natural history of the bowfin, Amia
calva, with colored plates of different stages in the development
of this singular fish.
In the Proceedings of the Biological Society of Washington,
1909, Dr. Barton Warren Evermann and Edmund Lee Golds-
borough describe a number of fishes from the canal zone of
Panama. Of these, Cheirodon gorgone, from Gorgona, is new.
In the same Proceedings, 1909, Dr. Barton Warren Evermann
and John Treadwell Nicholas describe the fishes of Crab Creek,
in the state of Washington, and with a new species or variation
of trout known as Salmo eremogenes. This is a very robust
form, with the spots gathered on the posterior part of the body.
It is apparently a variant of the cut-throat trout, Salmo clarki.
In the same Proceedings, 1909, Dr. Evermann and Lewis Rad-
cliffe have an interesting note on Orestias agassizii, a singular
fish from Lake Titicaca.
In the Memoirs of the Carnegie Museum, Volume 4, 1909, Dr.
Jordan and Robert Earl Richardson have a catalogue of the
fishes of the island of Formosa, or Taiwan, based on the collec-
tions of Dr. Hans Sauter. The fauna of this island is essen-
tially tropical, and intermediate between that of Japan and
that of India.. Most of the two hundred and eighty-six species
known are from sandy shores and bays, scarcely any collections
having been made among the coral reefs. In this paper nine
new species are described and elegantly figured.
In the Annals of the Carnegie Museum, Volume 6, 1909, are
three reports of the expedition to British Guiana of the Indiana
University and the Carnegie Museum. This is part of the work
undertaken by Dr. Carl H. Eigenmann under the joint patronage
of the two institutions mentioned, and having in view as its
18t THE AMERICAN NATURALIST [Vou. XLIV
final purpose a complete investigation of the geographical dis-
tribution of fresh water fishes in South America, and the rela-
tion of the barriers separating river basins to the development
of new species. The first of these reports by Dr. Eigenmann
gives new genera and species of fishes in British Guiana. A
remarkable feature of this investigation is the discovery that
almost all types of fishes found in different species in North
America are represented in South America by analogies be-
longing to the family of Characide. Thus, minnows, chubs,
suckers, darters and perches all have their representatives in a
family which is not represented by any of these, but which prac-
tically monopolizes the waters of South America.
The second of these reports, by Marion Lee Durbin, describes
one new genus and twelve new species of characins.
In the third report, Mr. Christian B. Blosser describes fishes
obtained, most of them incidentally, in the West Indies and on
the coast of Guiana. The following are new species: Apogon-
ichthys melampodus, from St. Croix; Bodianus stellatus, from
St. Croix; Holocanthus lunatus, of St. Croix ; Spheroides asterias,
St. Croix. Chromis marginatus, a species not previously found
so far north, was also found at St. Croix.
In the Proceedings of the Royal Society of New South Wales,
1908, Ogilby and McCulloch offer a revision of the Australian
Oretolobidx, group of carpet-sharks, some of them known locally
as wobbegongs.
In the Records of the Australian Museum, Allan R. MeCulloch
publishes studies in Australian fishes, No. 2, with descriptions of
a number of new or rare species from about Sydney.
In the Ann. Mus. Zool. of St. Petersburg, Volume 14, 1909,
Dr. Leo S. Berg demonstrates the distinctness of the genus
Acanthogobio from Hemibarbus.
In the same publication, Dr. Berg discusses the trout of the
Sea of Aral, Salmo trutta aralensis.
In the same bulletin, Dr. Berg discusses the salmon of the
Black Sea, Salmo salar labrax.
In the same bulletin Dr. Berg gives a list of the fishes of the
River Ob, or Obi, forty-two in number.
In a publication of the Provincial Museum of Natural History
and Ethnology, at Victoria, British Columbia, 1909, Mr. Francis
Kermode, curator, gives a list of the animals represented in the
collection, with excellent photographs of many of the species
of fish, as well as of birds, totem poles and other objects of
No. 519] NOTES AND LITERATURE 185
interest. This collection has the only two known specimens of
the prow fish, Zaprora silenus.
In the Proceedings of the Biological Society of Washington,
Volume 22, 1909, Mr. T. D. A. Cockerell, of the University of
Colorado, with Mr. Otis Callaway, has a very interesting dis-
cussion of the scales of fishes, as showing their genetic relation-
ship. In this paper the herbivorous cyprinoid fishes are treated,
and it is shown that the subfamily Chondrostomine, as recog-
nized in America, is even more heterogeneous than was hitherto
supposed. Chrosomus stands entirely apart from the others,
its scales having the primitive sculpture of the scales of the
suckers. The herbivorous forms in America are divided by
r. Cockerell into four subfamilies: Chrosomine, including
Chrosomus; Chondrostomine, including Acrocheilus and Or-
thodon; Campostomine, including Campostoma; and Pime-
phaline, including Pimephales and Hybognathus. These last
are most nearly related to the ordinary minnows. =
In the same Proceedings, 1909, Mr. Cockerell, and Miss Edith
M. Allison, continue the investigations of the scales of fishes,
with photographs of several of the different types. Taking up
the genus called Leuciscus, he suggests that probably none of
this species are congeneric with the European Leuciscus leu-
ciscus. If this view is correct, which seems probable, the name
Richardsonius should probably be adopted for the American
forms referred to this group. Lavinia is not one of the Chondro-
stomine, but it is closely related to the forms called Richardsonius.
Probably none of the American species referred to the genus
Rutilus of Rafinesque are congeneric with the Rutilus rutilus
which is an ally of Leuciscus. Mr. Cockerell separates Nocomis,
of which the type is kentuckiensis, from the genus Hybopsis,
basing the genus on the character of the scales. These are sup-
ported by numerous minor characters. Hybopsis gelidus is
made by Cockerell the type of a new subgenus, Macrhybopsis.
Cockerell regards Hybopsis, Notropsis and Cliola as derived
from Pimephaline.
These investigations of the character of the scales seem likely
to prove very important as indicating the real relationships of
these variant forms.
In the Bulletin of the Museum of Comparative Zoology, 1909,
Mr. Henry B. Bigelow describes the cruise of the United States
Fisheries Schooner ampun: in the Gulf Stream during
July, 1
186 THE AMERICAN NATURALIST [Vou. XLIV
In the Proceedings of the United States National Museum,
Volume 37, 1909, Professor Oliver P. Hay, discusses the nature
of the fossil sharks, with tooth-like structures, known as Edestus,
with a description of a new species and a new genus, Toxoprion.
Dr. Hay regards these, not as teeth, but as a succession of spines
or spinal structures in front of the dorsal fin, and used as
weapons of offense.
In the Proceedings of the National Museum, Volume 36, 1909,
Professor John O. Snyder describes new genera and species of
fishes obtained on the voyage of the ‘‘Albatross,’’ in 1906, on
the Coast of Japan and the Riu Kiu Islands.
In the Smithsonian Miscellaneous Collections, Volume 52,
1909, Barton A. Bean and Alfred C. Weed discusses the life his-
tory of the Alaskan fresh-water sculpin, Cottus asper. These
little fishes are extremely greedy and destroy great numbers
of salmon eggs.
The British Museum has published the first volume of an
elaborate catalogue of the fresh-water fishes of Africa, by Dr.
George Albert Boulenger. The first volume contains the
Mormyridx, the Characinide, and part of the Cyprinide, with
a number of minor families. The book is well printed, and
each of the species is represented by a good plate.
In Zoologica, for 1909, Mr. Edward Phelps Allis, Jr., pub-
lishes a most elaborate account of the anatomy of certain mail-
cheeked fishes, fifteen species being represented in his studies,
and the bony structure of each of these described with a degree
of fullness not hitherto shown in any papers on the osteology
of fishes. This piece of work is accompanied by admirable en-
gravings. The only suggestion which could arise by way of
eriticism is that not nearly all the types of the mail-cheeked
fishes are represented, and that a full comparative study in
which all of them would be considered might lead to results
which can not flow from merely descriptive work on a part of
a large and varied group.
In the Publications of the Department of Fisheries of New
South Wales, for 1908, David G. Stead discusses the beaked
salmon, Gonorhynchus, and its distribution in Australia.
In the same publications, Mr. Stead describes a number of new
species of fish from the coasts of New South Wales.
In the Annals of Queensland Museum, Number 9, for 1908,
Mr. J. Douglas Ogilby describes a number of new species and
genera from the coast of Queensland.
No. 519] NOTES AND LITERATURE 187
In a second paper Mr. Ogilby discusses the toad-fishes of
Queensland. A new genus, Batrachomeus, is proposed for
Batrachomaus minor, and a new genus, Coryzichthys, for
Batrachoides diemensis. This differs from the American genus,
Marcgravia, in a much smaller number of fin rays. A new
generic name, Halobatrachus, is proposed for didactylus of the
Mediterranean. This differs from Batrachoides in the presence
of an axillary pore.
In the index to the meeting of the British Association for the
Advancement of Science, at Winnipeg, 1909, Professor W. A.
Herdman gives an interesting discourse on ‘‘Our Food from
the Waters,’’ the investigation of plankton being made espe-
cially prominent.
In the Memoirs of the American Museum of Natural History,
Volume 9, 1909, Professor Bashford Dean presents studies on
fossil fishes (sharks, chimæroids and arthrodires). This con-
tains, among other things, an elaborate study of the genus
Cladoselache, a Devonian shark, and one of the simplest, as
well as the earliest, representatives of that group. Elaborate
drawings’ are given of the structural characters of Cladoselache,
and the final conclusion is that these represent better than any
other the primitive shark. Dr. Dean agrees with Woodward
that if the earliest true fish could be found, it would almost
certainly fall within the subclass to which belong our modern
sharks; and the fundamental characters of the cladoselachian
have given us a less ghostly picture of a direct vertebrate an-
cestor.
As to the arthrodires, Dr. Dean thinks that the present
evidence does not lead us to affirm that these fishes possessed
paired appendages homologous with pectoral and pelvic fins.
There is still, therefore, a great gap remaining between these
forms and the true fishes
In the Bulletin of the United States Geological Survey, Mr.
Earle Bernard Phelps discusses the subject of the pollution of
streams by sulphite pulp waste. The exclusion of these forms
of waste from the streams is one exceedingly important in the
protection of the fishes of our rivers. Thus far, it has not been
possible to prevent the flow of these mischievous substances into
the streams, and their value for utilization in other ways is
very slight. According to Mr. Phelps, the best promise seems
to be along the line of the formation from sulphite of the dye
called ‘‘lignone.’’ These substances dye wool directly, giving :
188 THE AMERICAN NATURALIST [Vou. XLIV
brilliant yellow, brown and green colors that are fast to soap,
acids and alkalies, and reasonably fast to sunlight.
In the Report of the Commissioner of Fisheries of British
- Columbia, 1908, Mr. John Pease Babcock, Commissioner, dis-
cusses the salmon problems of Puget Sound, and the Treaty of
April 11, 1908, under which the International Fisheries Com-
mission has been organized.
In the Comptes Rendus of the Academy of Sciences of Paris,
M. A. Cligny describes a new genus of Zein, called Parazen-
opsis, from Morocco. The species is Parazenopsis argenteus.
In the Annales de la Station Aquicole de Boulogne-sur-Mer,
M. Cligny shows that the species called Harengula latulus is
nothing but a common sprat, Clupea sprattus. The species
called Meletta phalerica and M. mediterranea are also identical
with the common sprat, the Mediterranean representatives of
which form a geographical race, distinguished from the races
in the north of Europe, having one less vertebra, and a few less
of the anterior rays.
In the same Annales, M. Cligny discusses the genus of
Scorpenide called Helicolenus. He shows that three distinct
species have been confounded under the name of maderensis.
Of these, the first, that of Cuvier, should disappear, being a
simple variety of Scorpana scrofa; the second, that of Lowe,
should receive a new name; the third, that of Goode and Bean,
should disappear, being a synonym of Helicolenus dactylopterus.
M. Cligny, however, conscientiously refrains from giving this
new species a distinctive name, because he has never had any
specimen in hand.
Nous ne nous permettons pas de donner un nom nouveau à une
espèce que nous n’avons jamais eue sous les yeux; nous laissons ce
soin & un naturaliste plus favorisé et qui pourrait donner en méme
temps un diagnose précise de l’espéce.
In the same Annales, M. Cligny discusses in greater detail the
new genus Parazenopsis.
In Notes from the Leyden Museum, Volume XXXI., 1909,
Professor Max Weber, of Amsterdam, describes new fishes ob-
tained by the Siboga Expedition to New Guinea and neighboring
waters. A number of new species are added to the endlessly
rich fauna of the Island of the Tropical Pacific. Rhabdamia
and Siphamia are new genera related to Apogon.
In another paper, in connection with the aquarium at Amster-
No. 519] NOTES AND LITERATURE 189
dam, Dr. Weber adds a new Fierasfer to the list of Siboga fishes.
In the AMERICAN NATURALIST, Vol. 42, 1908, Professor Cock-
erell describes the results of the expedition to Florissant in
1908. In this wonderful deposit of fossils, specimens of Tri-
chophanes foliarum, of Cope, were found. This little fish, of
which figures are given by Professor Cockerell, appears to belong
to the suborder Xenarchi, and to be a near relative of Aphre-
doderus, a living pirate perch. It shows also relationships with
the trout perch, Percopsis, like Aphredoderus, a relic of a wan-
ing fauna.
In the Records of the Canterbury Museum, Volume 1, 1909,
Mr. Edgar R. Waite gives an account of the scientific results
of the New Zealand Government Trawling Expedition of 1907.
A number of new species are described, one of the most inter-
esting being the blind torpedo, Typhlonarke aysoni. Only the
sharks and rays are discussed in this first paper.
Under the head of ‘‘Salmon Seales as Indicative of the Life
History of the Fish,’ Mr. J. Arthur Hutton publishes, in the
form of a paper read before the Manchester Anglers Association,
an article in which he shows that the scales of salmon are ob-
tained through life, and that in a general way the age of the
fish can be shown by the scales. During its stay in fresh water,
the scales rapidly disintegrate, and are restored again when the
fish returns to the sea. In his judgment the European salmon
does not live over eight or nine years. Mr. Hutton illustrates
his thesis by numerous photographs of salmon scales.
In the Memoirs of the Indian Museum, Volume 2, Dr. N.
Annandale, the superintendent of the museum, commences a
report of the fishes taken by the Bengal Fisheries Steamer
‘ Golden Crown.’’ The first paper treats solely of the rays,
of which numerous species were obtained. One partially blind
torpedo is given the name Bengalichthys.
In the American Journal of Obstetrics, Dr. Charles R. Stock-
ard discusses the formation of cyclopean monsters among fishes
by bringing up the little fishes in solutions of sea water con-
taining chloride or nitrate of magnesium.
The same subject is discussed by Dr. Stockard in the Anatom-
ical Record, Volume 3, 1909.
In the American Journal of Anatomy, Volume 9, 1909, Dr.
Harold D. Senior discusses the development of the heart in the
shad, with descriptions and bibliographies.
` In the Anatomical Record, Volume 1, 1907, Dr. Senior die:
190 THE AMERICAN NATURALIST [Vou. XLIV
cusses a number of rows of valves in the arterial bulb in the
heart in different fishes. In most bony fishes the arterial bulb
contains a single tier of valves. In Albula, there are two tiers;
in Elops one tier; in Pterothrissus two tiers.
In the Philippine Journal of Sciences, Volume 4, 1909, Mr.
Alvin Seale discusses very fully the fishery resources of the
Philippine Islands, with colored plates of a number of the more
valuable species.
In the same Journal, Mr. Seale discusses the sponge fisheries
of the Philippine Islands, with numerous plates.
In the Biological Bulletin, Mr. H. H. Newman, of the Uni-
versity of Texas, discusses hermaphroditism in fishes, a bisexual
specimen of Fundulus being considered, this being a species in
which the females are very differently marked from the males.
In the same Bulletin, Mr. Newman discusses the contact
organs, fine papille found on the scales and fins in certain fishes.
These have been studied by him in species of Fundulus at Woods
- Hole. These contact organs are supposed to give the fish greater
sensitiveness, and also, perhaps, to increase the frictional surface
of the animal.
In the Journal of the College of Science in the Imperial Uni-
versity of Tokyo, 1908, Mr. Shigeho Tanaka describes six species
new to science from the East Coast of Japan.
In the same Journal, 1909, Mr. Tanaka describes eleven new
species of Japanese fishes, one of them being a new genus of
Chimeras called Anteliochimera. This form has a snout pro-
duced in a long spatula, as in Rhinochimera. It adds one more
to the dozen or so extraordinary forms of sharks, skates and
chimeras which have been obtained within the last ten years in
the Bay of Sagami.
This specimen was caught, probably, with a hook, in a depth
of four hundred fathoms, by the remarkable collector employed
at the Seaside Laboratory at Misaki, Kuma Aoki. This un.
lettered fisherman, who can not read even his own language, is
in his way one of the cleverest ichthyologists in Japan.
In the Annotationes Zoologice Japonenses, Volume 7, 1909,
Mr. Tanaka diseusses a collection of fishes from the interior
province of Shinano.
In the Proceedings of the United States National Museum,
1909, Jordan and Richardson give a review of the sea bass, or
Serranide, inhabiting the waters of Japan, with numerous fig-
ures, and the description of one new species. When this series
No. 519] NOTES AND LITERATURE 191
of monographie reviews of Japanese fishes was begun, in 1900,
as a result of the exploration made in that year by Jordan and
Snyder, it was hoped that they would serve to furnish to Japa-
nese naturalists a record of the literature largely inaccessible
to them, and a record of descriptions of the known species. It
was hoped at the same time that making the literature of the
subject compact in this way would lead to a rapid development
of the science of ichthyology among the Japanese naturalists
themselves. The recent publications of Ishikawa, Kishinouye
Otaki, and Tanaka, and of other students of the great teacher,
Mitsukuri, have shown that these expectations have not been dis-
appointed.
In the Revista Universitaria, Peru, 1909, Professor Carlos E.
Porter, of Valparaiso, gives a list of the most important fishes
on the coast of Chili and Peru. Forty-six species are enu-
merated.
In the Publications of the Bureau of Science of the Philip-
pine Islands, at Manila, Jordan and Richardson give a check list `
of the fishes known to inhabit the waters of the Philippine
Islands. This list, based on the various collections made under
the auspices of the United States Government, and of the local
Bureau of Science, now numbers eight hundred thirty species.
It is probable that a full enumeration of the fishes of these
islands will rise to double that number. One new genus is
proposed in this paper, Vespiculus for Prosopodasys gogorza.
: Davip STARR JORDAN.
ENTOMOLOGY
_ A New Catalogue of Hemipterous Insects.'—A catalogue exhibits
the taxonomy of a group in its most condensed form. For this
reason, it is as interesting and valuable to a specialist as it is un-
interesting and unintelligible to one who has paid no attention to
the particular order or family it represents. It has indeed a very
high value for the uninitiated, inasmuch as it gives him a clue to
the literature on and affinities of any particular form he may
need to investigate; but it is only the specialist, who has long
worked on the group, who can at once appreciate its dramatic
significance. The present reviewer ventures to consider himself
an hemipterist of a sort, but his particular speciality has been the
tail of the order, as it were, while the first volume of the new
***Catalogue of the Hemiptera T by G. W. Kirkaldy,
Vol. I, Cimicide. Berlin, F. L. Dames, 1909.
192 THE AMERICAN NATURALIST [ Vou. XLIV
catalogue deals with the head. This circumstance furnishes a
rather welcome excuse for avoiding all discussion of the numer-
ous disputable points in nomenclature with which the work nec-
essarily bristles, but leaves the way free for remarks of a more
general character.
It is interesting to find that the new catalogue of an order so
extensive and of such economic importance as the Hemiptera
has been written in the Hawaiian Islands, and published in Ber-
lin. One would have supposed it equally impossible to prepare
a work of this sort in such a remote locality, and to persuade a
German publisher to bring it out—in English! Here it is, how-
ever, and so far as a rather careful scrutiny reveals, it is well
above the average of such things in completeness, accuracy and
typographical excellence. The price also is reasonable enough.
It is no mere list of names and references; localities, food-plants
and natural enemies are fully cited, while great care is
taken to include all sorts of biological and even embryolog-
ical citations. At the beginning of each subfamily or tribe
is a table showing the geographical distribution of the genera,
bringing out various interesting facts. Thus the great
number of genera of Acanthosomini in Australia and in
the Chilean region is remarkable, and might be offered as an
additional argument for a former land connection. It appears,
however (if the genera are arranged in correct systematic order),
that the Australian and Chilean types stand far apart and are
more related to those of the Oriental and Palearctic regions than
to one another. All fossil species are included: the author re-
marking that ‘‘considerable misapprehension regarding these is
due to the absurd and unphilosophical separation, by most geol- —
ogists, of present (Pleistocene) time from the rest of the Tertiary
(or Kainozoic) as a ‘‘Quaternary’’ epoch. The feeling that the
species of the older Tertiary periods are the direct precursors,
with but little separation in (geologic) time, of present-day
forms, is thus lost, and these interesting relics are regarded with
indifference by the majority of entomologists.’’ While it is not
probable that the present geological classification will be aban-
doned, it must certainly be admitted that if the Tertiary period
is made to inelude an amount of time at all comparable to that
of its predecessors, we are not merely in the Tertiary at this |
moment, but not far from the e i gees of it!
T. D. A. CocKERELL,.
BOOKS WILLIAM J. l GERHARD,
CALLOWHILL STREET, PHILADELPHIA, PA.,
offers the ARPES at affixed net prices. Extended catalogues
of books and pamphlets in all branches of natural history post-free on request :
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Methods in Plant Histology
By CHARLES J. CHAMBERLAIN
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vo, cloth ; net $2.25,
postpaid $2.39
HE first complete manual to be published on the subject of botanical micro-
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Tt contains detailed directions for collecting and preparing plant
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tages of the different m
Will no doubt find a place in every well-regu-
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private students.—Plant Worl:
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A inboratory Guide in Bacteriology
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CLEAR and concise de ghee of bacteriological technique, designed prin-
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e instruction given is clear and accurate,
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A book such as this must facilitate "ari sek
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Animal Micrology:
Practical Exercises in Microscopical Methods
By MICHAEL F. GUYER,
250 pages, 8vo, cloth ; net $1.75, postpaid $1.88
HE title of this book will explain its scope.
manual ea textbook use. Its aimis
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than descriptions of reagents or appar
It is intended as a laborato
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ufficient account of the theoretical
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directions are Sw explicit, and com-
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The medical student ne will find it very useful as
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can Medical Aassociatio
This is one of the iinet works on microscop-
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One of the best and most practical works upon
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As a textbook it can hardly be improved.
research worker will find in this book norte the in-
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Review.
It does present in very clear form a judicious
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principles, adequate for the under te co
in ne a A Journal of Comparative Neurology ;
ADDRESS DEPT. 64
Chicago
THE UNIVERSITY OF CHICAGO PRESS
New York
VOL. XLIV, NO. 520 APRIL, 1910
<j
we
THE
AMERICAN
NATURALIST
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
The Origin of the Electricity Tissues in Fishes. Professor ULRIC DAEL-
GREN
The Sarri bit of ROPE Phenomena. Dr. -iain | R. diris 203
Mendelian Phenomena without de Vriesian Theory: Dr. W.J. SPILLMAN 214
The Evolution of New Forms in Viola T RESF Professor EZRA
AINERD
Tertiary Archhelenis. Dr. A. E. ‘ ORTMANN è > . > à .
Shorter Articles and Discussio
The Probable PER, of Ga paoa Neryous System: AUSTIN H. CLARK 243
Notes and Literatur
The Question of sak Doiii Professor H. E. Jorpan. Recent Inv
tigations on the Comparative Anatomy of Conifers: Professor E. C. J rier a45
THE SCIENCE PRESS
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THE
AMERICAN NATURALIST
Vou. XLIV April, 1910 No. 520
THE ORIGIN OF THE ELECTRICITY TISSUES
IN FISHES!
PROFESSOR ULRIC DAHLGREN
PRINCETON UNIVERSITY
Amone the many specializations of animal tissues four
are so fundamental in nature and so specific in their func-
tion that they stand out as exceptionally favorable objects
for study, particularly as to their origin and evolution.
These tissues are those which produce motion, heat, light
and electricity in quantities, and for the benefit of the en-
tire organism.
Of these, motion is the most important. Without the
power to move it is probable that few animals would be
able to survive and to evolve to any great degree of spe-
cialization. Thus the forms which did not develop organs
of motion at an early period or those which lost it sub-
sequently would be eliminated and would leave all other
and higher degrees of specialization to be attained by
such animals as had developed or retained muscle tissue.
Heat production was probably an important factor in
the development of many land forms, especially in regions
of the earth that became subject to cold, and the posses-
sion of any small part of this power would tell to a
marked degree in the favorable selection of its possessor.
1 Lecture delivered before the Society of American Naturalists in Bos-
ton on December 29, 1909. A fuller technical account with illustrations of
the histogenesis of the electric tissue in Gymnarchus will shortly appear in
another journal.
193
t
194 THE AMERICAN NATURALIST [Vou. XLIV
Of the other two abilities, that to produce light and to
generate electricity, we find that both are rare. Lumi-
nosity is found to be widely distributed among the various
kinds of animals, most of the principal groups having one
or more representatives which can produce light. And
yet this is, after all, a rare specialization and the percent-
age of animals which are luminous is very small indeed.
It is not so absolutely necessary as the power to move
nor can it be regarded as having the selective value that
the possession of heat-producing tissues must have. Its
real function, sexual, warning, or for purposes of seeing
objects in the dark, has not been satisfactorily determined
for any groups except possibly the deep-sea fishes and
even here we find more to be without it than with it.
As to the last of the dynamic tissues, that which pro-
duces electricity, we have here a tissue which is remark-
able to an extreme degree both for the rarity of its occur-
rence and its narrow distribution, is being confined to one
group of vertebrates, the fishes, and found here among
only seven families.
In these seven groups the tissue seems to have devel-
oped absolutely independently and to have formed seven
separate types of organ differing markedly from one an-
other in details of structure and position of the organ and
yet all adapted, through certain analogous developments,
to perform the same function.
We evidently have here a tissue of comparatively
recent origin, phylogenetically, and one of the first studies
to be made toward a knowledge of its evolution is to find
out what can be learned from its history in the individual
or its histogenesis.
Of the seven types of organs two are found in elasmo-
branchs and the remaining five in teleost fishes. The
histogenesis of the two elasmobranch forms has been
worked out by Ewart, Engelmann, Babuchin, Ogneff and
others, but the corresponding history of this tissue in the
teleosts has remained unproved with the exception of one
form, Gymnarchus, the ontogenetic origin of whose elec-
tric organ the writer presents below.
No. 520] ELECTRICITY TISSUES IN FISHES 195
Before explaining the histogenesis of the electric tissue
in this teleost fish a brief résumé of what is known of the
development of the two elasmobranch types of electric
tissue should be given.
In the young embryos of Raja, Ewart and Engelmann
found that the position of the future electric organ was
occupied by well-developed muscle in no way different
from the other muscle tissue of the trunk. In the half-
developed fish the transformation of certain of these sin-
gle muscle fibers into single electroplaxes was observed
to begin, at a later period in those skates which had the
simpler types of tissue, at an earlier time in those which
had the more highly developed types. This change in the
muscle fiber consisted of a widening of its anterior end,
which finally resulted in the formation of a flat plate lying
at right angles to the position of the former muscle fiber.
The posterior end of the fiber degenerated, forming in
some cases a useless tail-like appendage in other cases
atrophying altogether.
During this change the myo-fibril bundles assumed var-
ious curved positions and formed the thick ‘‘ striated ”’
layer of the electroplax, while the larger part of the cyto-
plasm formed a flat anterior layer or ‘‘electrie layer” as
well as a thick covering, the nutritive layer, on the pos-
terior surface. This posterior layer was produced into
more or less developed papille. The nuclei multiplied
by amitotic division and were segregated into the ante-
rior and posterior layers, those in the anterior or electric
layer forming a very regular layer themselves. The
nerve supply, consisting of several medullated fibers, ap-
proached the anterior or electric surface and, dividing
into very many fine naked branches, terminated in as
many disc-shaped plates in this surface.
In the torpedoes, or electric rays, Ogneff has worked out
the histogenesis and found that, as in the other elasmo-
branch forms (the skates), each electroplax develops from
one muscle cell. But there are several important differ-
ences. The adult organ is a far more highly specialized
structure in Torpedo than in Raja and the muscle cell is
196.” THE AMERICAN NATURALIST [ Vou. XLIV
still in a very young stage, a mere myo-blast possessing
but one nucleus, at the time it begins to change. It is the
end furthest from the electric surface or negative pole
of the future electroplax that begins to enlarge first
into a eclub-shaped form and then into a dise which
continues to expand laterally and grow thinner until it
becomes an exceedingly thin plate. The nucleus of the
young myoblast or electroblast divides by amitosis into
many nuclei, which are distributed through the plate and
the nerve supply is large and ends in tiny discs that cover
the whole upper, negative or ‘‘ electric °’ surface.
In Gymnarchus, the only teleost whose histogenesis is
known, the electroplaxes of the adult fish are arranged in
eight long cylindrical masses, four on each side, and em-
bedded in the muscle of the tail. Each cylinder consists
of a row of the thick electroplaxes spaced apart by about
their own length of the jelly-like ‘‘ electric connective
tissue’’ usually found in these organs. Each electroplax
conforms to the outline of the cylinder laterally and is
bounded anteriorly and posteriorly by surfaces from
which a few short blunt papillae emerge. The electro-
plax consists of a central core of a fibrillar nature, the
fibrils being arranged in the form of approximate layers
and giving the appearance of a transverse striation of this
region. As will be seen below, this striation does not
represent the striation of the voluntary muscle of verte-
brates.
This core is covered by a layer of undifferentiated cyto-
plasm of moderate thickness which contains the numerous
nuclei of the syncytium. The nuclei are arranged in a
single layer, but, since the central core does not extend
into the majority of the papilla, the nuclei form a central
mass in these appendages.
The nerve supply consists of several large medullated
fibers which approach each electroplax from the rear and
are easily seen to end on its posterior surface. Each of
the naked ultimate branches terminates in a knobbed end
plate which is imbedded in the substance of the outer
No. 520] ELECTRICITY TISSUES IN FISHES 197
layer both on the papille and on the posterior surface
itself.
The whole cylinder, both electroplaxes and electric con-
nective tissue, is separated from the surrounding mus-
cle tissue by a connective tissue sheath in which a few
isolated pigment cells are to be seen. The electroplaxes
do not exactly correspond in the adult either to the myo-
tomes or to the vertebre.
The significant development of the electric tissue takes
place between the ninth day of embryonic life, at which
time the embryo contains unchanged muscle tissue in its
tail, and the 40-day embryo which possesses the organs in
practically its adult condition. The critical changes take
place within even closer limits; from the 11th day to the
15th would include them. The stages used in this exami-
nation were but four in number, the ninth, eleventh,
twelfth and fortieth, four out of the seven valuable em-
bryos given the writer by Dr. Arthur Shipley, Dr. Richard
Assheton and Dr. J. Graham Kerr, to whom many thanks
are due. This material was collected by Mr. John Sam-
uel Budgett in Africa, he most unfortunately losing his
life from fever shortly afterwards.
The ninth-day embryo shows no trace of any electric
tissue. The myotomes, as shown in a longitudinal section
are very regularly formed and are composed at this time
of many perfect muscle fibers with the myofibrils devel-
oped in several bundles in the peripheral cytoplasm.
These muscle fibers are all parallel with one another and
with the long axis of the body. Connective tissue is but
little developed although it is found sparingly between
the muscle fibers.
In the embryo of eleven days the electric tissue has be-
gun to form. Eight regions in each muscle segment,
each region composed of a few (10-40) of the young
muscle fibers, have become prominent through the slightly
greater density of their cytoplasm and the beginning de-
generation of the muscle cells which immediately sur-
round them. These eight regions in each myotome lie
directly in front of and behind eight corresponding
198 THE AMERICAN NATURALIST [ Vou. XLIV
regions in the myotomes before and to the rear of them.
They thus mark out anterio-posterior lines which repre-
sent the location of the future cylinders. The young
muscle fibers composing them retain their myofibril bun-
dles unchanged and the striation of these fibrils is exactly
like that of all the other myofibrils in other muscle fibers.
The multiplication of nuclei goes on by amitosis as in the
regular muscle cells.
The next stages examined are seen in an embryo whose
age was between twelve and fourteen days. ‘The word
‘‘stages’’ is used because in such an embryo quite a range
of developmental steps can be found, owing to the fact
that the tail is still extending and consequently the ante-
_ rior electroplaxes are older than the posterior. This con-
dition is reversed in the adult, for here it can be seen
that the posterior electroplaxes advance further in size
and degree of specialization than the anterior ones did.
A young stage in this embryo shows that the groups of
cells in each myotome which are forming the electro-
plaxes have become so closely approximated that they
form a larger syncytium composed of the several smaller
syncytia or muscle fibers which went to form it. This
mass has assumed a rather distinct, elongate, spindle-
shaped form and each one has increased in length so as to
overlap its neighbor both ahead and behind it by a third
or more of its length. The myofibrils show a tendency to
occupy the central core of the young electroplax and are
still striated. In this stage the nerve supply can be seen
approaching the spindle from somewhat behind its mid-
dle and coming in contact with it at about the junction of
its middle and posterior thirds.
The older electroplaxes in this same stage show a
change. This change consists in a segregation of the
myofibrils in the central core of the mass, where they still
run parallel with each other and in a straight anterior-
posterior direction; except in the now swollen middle
third of the structure where they have assumed a wave-
like direction. Furthermore, they have lost the larger
part of their striation, this feature being retained only in
No. 520] ELECTRICITY TISSUES IN FISHES 199
either end of the fibrils. The less differentiated cyto-
plasm has become segregated into a peripheral layer and,
owing to the more rapid growth in length of the entire
body than of the individual electroplaxes, these latter
have become drawn apart and no longer overlap as they
did at an earlier date.
Before proceeding further a word is necessary as to
the fate of the surrounding muscle fibers and the way in
which the electroplaxes become marked off from the sur-
rounding tissues.
At first the muscle cells that will be transformed into
electric tissue are in direct contact with the surrounding
muscle cells of the myotome. Then these immediately
surrounding fibers begin to degenerate by a peculiar proc-
ess of hystolysis that strangely enough resembles some-
what the formation of an electroplax. The middle of the
fiber swells up and the myofibrils lose their striation;
lastly the ends are drawn in, the nuclei fragment and the
whole mass becomes a lump of amorphous matter that
finally disappears.
The next developmental changes in the electroplax can
perhaps be best described by comparing the stage last
described with the practically adult electroplax. In this
we find that the middle third of the young form has ex-
panded into the cylindrical body of the completed stage.
The two end portions have failed to grow in size and
have become one of the several blunt papille that have
evaginated from both ends. This comparative atrophy
of the posterior end of the spindle has left the nerve
ending on the posterior surface of the electroplax and
on the evagination that project from it, while the anterior
end is in contact with a considerable development of capil-
lary blood channels that lie in the electric connective
tissue.
Most interesting in this older stage is the fate of the
myofibrils. They have lost their striation completely,
the dark staining anisotropic substance seeming to have
dissolved and left well-defined fibrils of the isotropic sub-
stance alone. These fibrils no longer lie so evenly to-
gether although still associated in groups. The wave-like
200 THE AMERICAN NATURALIST [ Vou. XLIV
direction that they had previously assumed has increased
until they now run back and forth at right angles to the
axis of the electroplax and consequently in the same re-
lation to their former course. This gives the striated
appearance which might be taken for the degenerated
remains of the real muscle striation that the developing
electroplax formerly possessed.
We thus can see that, while the electroplax of Raja and
of Torpedo were formed from single muscle cells, in the
first case by a widening of the negative or electric end and
in the second instance by a widening of the positive or
nutritive end, the electroplax of Gymnarchus is formed by
the association of several myoblasts into a single syncy-
tium and the widening of the middle part of this struc-
ture into the electroplax.
The other anatomical features of Gymnarchus which
have caused it to be classed with the Mormyride demand
that a comparison of this organ be made with the appar-
ently widely different organ found in the various mor-
myrus groups. That found in Mormyrus Oxyrynchus
will serve as a type and its general plan has been well
shown by Ogneff and Schlichter. Here it is evident that
a number of consecutive and entire myotomes have been
converted into electroplaxes and that the middle layer of
each electroplax is composed of unaltered and clearly
striated myofibril bundles. The large number of these
fibril bundles and their distribution indicate that the
whole electroplax is a syneytium composed of all or most
of the cells which would otherwise have gone to make
up the single myotome. In this we find an agreement
with the electroplax of Gymnarchus which is also formed
from several cells. In the one case all the cells in the
myotome have been used; in the latter only those lying —
in eight particular localities.
Further homology is seen in the disposition of the
probably superfluous myofibrils. In both forms they are
relegated to a middle position in the electroplax while
the apparently more important cytoplasm forms layers
on the anterior and posterior surfaces of the structure.
Also, in both, the now useless myofibril bundles are
No. 520] ELECTRICITY TISSUES IN FISHES 201
packed out of the way at right angles to the axis of the
electroplax which remains the same as the former axis of
the muscle cells that were used to form it.
The only difference lies in the fact that the striation
of the fibrils is retained in the Mormyrus forms while it is
lost in Gymnarchus, the dark-staining anisotropic sub-
stance apparently dissolving away.
From what little can be predicted concerning the possi-
ble origin of the electric tissue in the other teleost forms
it is probable that the Mormyride (including Gymnar-
chus) are the only fish in which the electroplax is formed
as a syncytium from more than one cell. In Astroscopus,
Electrophorus (forming Gymnotus) and Malopterurus
the structures show every evidence of having been devel-
oped from single myoblasts with the exception of Malop-
terurus, where it is a question as to whether they are not
evolved from gland cells instead.
The evolution of these structures was most probably
not based upon a natural selective basis. It is true that
all muscle cells produce a slight statie discharge at the
moment of contraction, and that the far greater shock
given by the electroplax is possibly a development of
this same discharge. But Darwin in his ‘‘ Origin of
Species ° has already said that the electric organs of
fishes were one of the serious obstacles in the way of his
natural selection theory, showing that the very slight dis-
charge of the more primitive organs could not possibly
have been useful to their possessors to the extent of an
excluding selection based on their presence or degree of
development.
Some good evidence as to the methods of evolution
ought to be deduced from the degree of specialization and
distribution of electric organs in some of the groups;
even if experimental work seems at present to be impossi-
ble. In the skates, for instance, we find a very even and
general distribution of an organ and tissue that is ap-
parently in course of evolution, but which has not yet
arrived at a state of efficiency. It seems that the organ
must have originated in the common ancestor of the thirty
or more species of skates found in the seas of the world.
202 THE AMERICAN NATURALIST [ Vou. XLIV
All the Rajide have this organ and yet their close allies
show no sign of its appearance. One form in particular
was formerly classed with the skates, but some years ago
was removed on anatomical evidences from this group by
D. S. Jordon and classed in another genus. The writer
‘dissected a specimen of this species with great interest
and care and found that there was no trace of electric
tissue. And yet this species is undoubtedly closely re-
lated to the skates and must have inherited at least their
potential powers to develop electric tissue. Furthermore
this species is skate-like to an extreme degree in form
and habit and must have lived under conditions and sur-
roundings similar to those which we must assume were the
ones, if any, that stimulated the skate ancestors to change
muscle tissue into electric tissue. Evidently there are
internal as well as external conditions and stimule to be
taken into account.
Likewise among the torpedoes; all possess a very highly
developed organ, evidently a common inheritance from
some ancestor in which it originated. Subsequent varia-
tion in the tissue has not kept pace with the fair amount
of external variation in the several species. It seems
that the impulse to evolve this tissue has extended into all
the members of these two groups, a real inner stimulus
working independently of outer condition.
On the other hand, other groups of similar form, appear-
ance and mode of life to some of the other electric fishes
‘absolutely lack the electric tissues. These may or may
` not be nearly related. A rather remarkable example is
to be seen in Astroscopus and its related form Urana-
scopus scaber. These two fish look so much alike that
one may be used to show the fishermen what the other
looks like. Their habits are practically the same. Also
this feature is noticeable among the Gymnotide, whose
various members show many grades of specialization but
have not been sufficiently studied as to the possession of
rudimentary electric organs. These studies together with
the histogenesis of other teleost electric tissues, particu-
larly that of Malopterurus, are most attractive fields for
future work. a
THE MATERIAL BASIS OF MENDELIAN
PHENOMENA?
DR. REGINALD R. GATES
Missour! BOTANICAL GARDENS, Sv. Lours, Mo.
Since the rediscovery of Mendel’s results at the begin-
ning of the century, a very extensive and important field
of hereditary phenomena has been actively developed,
and the conceptions and explanations of Mendelian be-
havior have been changing with great rapidity. Many
explanations and views of the phenomena of dominance,
recessivity, latency and segregation have been proposed,
- and the only conception of Mendel which has remained
essentially unmodified by Mendelians is that of the purity
or unity of the characters in the gametes. Even this
conception has been viewed by various workers in many
lights, with a more or less complete and sweeping denial
of an actual segregation of characters in the germ cells.
In the time at my disposal I shall bring before you
the results of only one @nothera cross, which shows Men-
delian behavior in certain characters, and in the discus-
sion of these results shall point out certain modifications
of our conceptions of Mendelian segregation which they
necessitate.
The cross in question is C£nothera nanella X O.
biennis, O. nanella being a mutant from O. Lamarckiana
and the O. biennis in the cross being from a wild race
growing around the New York Botanical Garden. The
seeds were first obtained from Dr. D. T. MacDougal. In
the F, of this cross two types were produced, evidently
corresponding to DeVries’s twin hybrids. One of these
types breeds true in the second generation and is the
same as the type obtained in the F, of O. Lamarckiana
X O. biennis. The other is a new type, with unexpected
1 This paper was presented oes the American Society of Naturalists
in — Mass., December 29,
203
204 THE AMERICAN NATURALIST [ Vou. XLIV
characters, which I have called O. rubricalyx. None of
the peculiar characters of either parent are present in
this hybrid. But this is not so remarkable, because
crosses between the (Znothera mutants frequently lose
the distinctive marks of both parents and give O. La-
marckiana. The same form, O. rubricalyx, has appeared
in my cultures as a mutant or extreme variant from O.
rubrinervis, from which it differs only in possessing a
red hypanthium instead of green, a marked increase in
the red color pattern of the sepals (the median ridge of
the sepals being also red instead of green), and in the
production of a conspicuous quantity of red pigment on
the under surface of the petioles of the rosette leaves, as
well as in other parts of the plant. The type can there-
fore easily be recognized by observing the under surface
of the rosettes, and in the flowering stage the conspicuous
deep red buds render the plant very attractive and showy,
distinguishable from O. rubrinervis at a glance. It dif-
fers from O. rubrinervis in its greatly increased capacity
for anthocyanin production, a difference which expresses
itself in nearly every organ of the plant. A full illus-
trated account of this cross will be published elsewhere.
In the F, this type splits in the Mendelian ratio of
3:1, giving approximately 75 per cent. O. rubricalyx and
25 per cent. O. rubrinervis. I have not yet bred the
later generations, but the O. rubrinervis may be expected
to breed true and the O. rubricalyx to split as before.
In this single cross there are many facts which throw
interesting side lights on the nature of Mendelian be-
havior. In the first place, only one character splits in
Mendelian fashion, the others remaining true. Hence,
if proof of this proposition were needed, here we have
proof that Mendelian phenomena are not universal, even
in the forms in which they occur. The O. rubricalyx
which appeared as a mutant from O. rubrinervis also
splits in the same manner, a certain number of the off-
spring reverting to the rubrinervis condition, though I
have not been able to determine whether this is a Men-
delian ratio. These and other facts make it very prob-
No.520] BASIS OF MENDELIAN PHENOMENA 205
able that the explanation of Mendelian phenomena is to
be sought in the nature of the character itself, which
conditions and perhaps determines this type of in-
_heritance.
Another important point in connection with this hybrid
is that the split in the F, does not produce a return to
the condition of one of the grandparents, as in typical
Mendelian behavior, but the difference between the two
types of the ,—O. rubricalyx and O. rubrinervis—is a
purely quantitative difference, in capacity for pigment
production, although morphologically this difference is
expressed in certain very definite regions of the plant.
There are no intermediates between these two types,
each being an independent condition of stability. The
difference, therefore, clearly dates back to the germ cells,
That a quantitative difference between germ cells in
their capacity for pigment production can behave in
Mendelian fashion, showing the phenomena of dominance
and segregation, is of fundamental significance in the
interpretation of the nature and material basis of these
phenomena.
Riddle (’09) has brought together in an interesting
way the facts of physiology and biochemistry which show
that the various pigment colors in mammals and other
animals are different stages in the oxidation of a single
melanin pigment by the enzyme tyrosinase. In the light
of the facts of quantitative Mendelian inheritance which
I have presented, it is clear that color inheritance in
the mammals can also be most easily interpreted as a
ease of quantitative inheritance, due to initial quantita-
tive differences of some sort in the germ cells themselves.
It is not impossible that nearly all Mendelian inheritance
may be found, on sufficient analysis of the characters, to
be of this sort. Studies in variation show that many
apparently qualitative differences, when analyzed, are
found to be purely quantitative in origin. It should be
remembered in the case of melanin pigments, as Riddle
also points out, that while some tyrosin oxidations lead
to the formation of melanins, others result in the usual
206 THE AMERICAN NATURALIST [Vou. XLIV
waste products, such as carbon dioxide and ammonia.
Of course, only the former can be of significance in in-
heritance, and it is probable that whatever determines
in how far the former process of tyrosin oxidation shall
take place, will be found to control or determine these `
quantitative differences in the end-products of the germ
cells.
It is interesting and suggestive to note in this connec-
tion that Morgan (’09) has adopted a quantitative inter-
pretation of the sex-determining factors in the germ cells
of insects and other organisms.
It is important to enquire what is the nature and origin
of this quantitative difference, such as must occur in the
germ cells of the hybrids I have described. It is most
reasonable to suppose that it originates at the time the
germ cells are formed, i. e., during the reduction divi-
sions, for the whole individual from a very early stage
of the seedling to mature development shows one or the
other of the alternative characters. Hence, the germinal
difference must date back to the fertilized egg, and if
this be true we must logically take it back farther still,
on account of the definite Mendelian proportions, to the
individual germ cells which united in fertilization, and
hence probably to the reduction divisions.
The question of the relation of the chromosomes to
Mendelian behavior has been so often discussed that I
will only touch upon it here, to point out that the theory
of qualitative hereditary differences among the chromo-
somes is not incompatible with the view that differential
Mendelian characters are properties of the germ cell as
a whole. If, during the reduction division, certain of the
chromosomes which are segregated into separate cells
are chemically unlike, then different groupings will
arise and the whole germ cells whose nuclei the different
groups enter will soon experience the effect of those
differences, and accordingly such germ cells would be
expected to become unlike as a whole. This follows
necessarily, not only from the continual active inter-
No.520] BASIS OF MENDELIAN PHENOMENA 207
changes in metabolism between nucleus and cytoplasm,
but from the unity of the cell, which modern biology has
abundantly proved. Hence there is no difficulty in sup-
posing that differences which must be thought of as
characterizing the germ cell as a whole, originated from
chromosomal differences during reduction. On the other
hand, there seems no necessity for assuming that all
germinal differences originate in the chromosomes,
although if they originated in the cytoplasm it is neces-
sary to assume as a vera causa either a separation of
cytoplasmic substances during reduction, of which we
have no visible evidence, and which seems unlikely for
various reasons, or quantitative cytoplasmic differences
in the cells of a tetrad. The quantitative difference
which must exist between the germ cells of O. rubricalyx
and O. rubrinervis may possibly be conceived of as origi-
nating in the cytoplasm and then becoming a property
of the germ cell as a whole.
It is even possible that this is not a difference in
amount of matter of any sort, but rather in the energy-
content of the two types of germ cell, although we
have no means of knowing how or why such a marked
difference in energy-content should arise.
To attempt to account for the manner of origin of a
O. rubricalyx mutant from a O. rubrinervis germ cell
would at the present time be purely speculation. De-
Vries’ conception of a new unit becoming suddenly acti-
vated in the germ plasm seems too formal an assumption
to be accorded the dignity of an explanation. The fact
that the O. rubricalyx mutant reverts to O. rubrinervis
may be looked upon as evidence in favor of his view
that a mutant originates as a hybrid, from the union
of a mutated with a non-mutated germ cell.
I should also point out that the origin of O. rubricalyx
from O. rubrinervis may perhaps be significant as indi-
cating an orthogenetic tendency to an increase of pig-
ment production, although this increase has taken place
by definite germinal steps, particularly in the origin of
O. rubricalyx from O. rubrinervis.
208 THE AMERICAN NATURALIST [ Vou. XLIV
The significance of the fact that I have succeeded in
producing O. rubrinervis as one of the types resulting
from this cross, is too obvious to require pointing out.
In the light of these facts, it is not impossible that other
mutants can be similarly synthesized.
Much experimental work has been directed to the study
of the physiology of anthocyanin production in the plant.
Without entering into the details of this work it may be
said that two general theories of anthocyanin production
have been developed. EH. Overton (799), Mirande (’07),
Molliard (’07) and others conclude that it arises from
an accumulation of sugars in the cell sap, which unite
with tannic acid to produce a glucoside. Overton showed
experimentally that low temperature and high light in-
tensity both cause anthocyan production. Mirande (’07)
called attention to the development of red in leaves eaten
by insects; and Combes (’09a) produces the same result
by annular decortication. In every case the result is
interpreted as due to an accumulation of sugars. J.
Laborde (’08), from his experiments deduced a slightly
different view, namely that formaldehyde or one of its
polymerization products may cause tannin transforma-
tion, to produce color. Further, Overton, Laurent,
Molliard and others, found that various seed plants
grown in sugar solution show a marked increase in
anthocyan production, which indicated clearly a relation,
direct or indirect, between the presence of sugars and
the development of anthocyan. Whether such an in-
crease in anthocyan production is inherited is not known,
but presumably it would not be inherited. Of course,
many variations in pigment production are of a non-
heritable sort, but it is equally certain that in O. rubri-
*In this connection I may call attention to certain observations of my
own upon the effects of the attacks of a certain insect on the buds of
Ginothera. The very young buds are stung by this insect and such buds
undergo several characteristic changes in development. The hypanthium
fails to develop and the base of the cone becomes very thick. In O.
— Pons the same is true at Jeast of several mutants) there is
also always a conspicuous amount of red. developed on the sepals under
these diiis but the buds of O. chistes while they undergo the
same morphological changes, never develop any re
No. 520] BASIS OF MENDELIAN PHENOMENA 209
calyx the increased pigment production ‘is a heritable
character, and therefore the change which brought it
about must have been of a fundamental sort, in the germ
plasm.
A more recently developed hypothesis of anthocyan
formation, suggested by Pick in 1883 and supported by
the work of Palladin (’08), Buscalioni and Pollacei (’04),
in their extensive memoir, and others, is that anthocyan
originates from the action of oxydases upon the respira-
tory chromogens of the cell, the latter being aromatic
bodies which on oxidation yield colored compounds. The
experiments of Molliard (’09) support the latter theory
by showing the necessity for the presence of oxygen in
anthocyan production. Molliard also showed that, when
grown in a sugar solution, the respiratory exchanges of
plants are more intense.
Combes (’09b) has recently harmonized the two
theories. He shows that there is a close relation be-
tween the production of anthocyan and an increase in
the proportion of sugars and glucosides in the cell sap.
He concludes that since the formation of anthocyan, a
compound of glucoside nature, is correlative with an in-
crease of the total glucosides, the anthocyan cannot be
formed from preexistent glucosides, but from some other
source; and since there is also an increase in chromogens
(Palladin) therefore anthocyan is not derived from
chromogens already existing, but its formation must be
provoked by the accumulation of sugars, which increases
the respiratory exchanges and appears to determine the
acceleration of oxidation processes. Under these condi-
tions the production of glucosides is increased, and these
are, in part at least, anthocyanins.’
It is scarcely necessary to point out that, whatever may
be the chemistry and physiology of anthocyanin produc-
tion, in the case of @nothera rubricalyx there must have
been a fundamental change in the germ plasm by reason
of which, under the same external conditions as O. rubri-
* See also the ay recent papers of Miss M. Wheldale. Proc, Roy.
Soe. gigs B, 81: 41-60. Proc. Cambridge Phil. Soc. 15: 137-168 and
Reports o the Bvalution Committee of the Royal Society, V., PP- 26-31,
1909.
210 THE AMERICAN NATURALIST [ Vor. XLIV
nervis, it reacts with much greater pigment production ;
a reaction which shows itself with great definiteness in
the buds and the rosette leaves.
Although plants and animals equally exhibit Mendelian
phenomena, yet the part of the organism which must be
looked upon as constituting the germ plasm, and hence
the basis of such phenomena, shows several important
differences in Metazoa and Metaphyta, two of which may
be pointed out. Most important of these differences is
probably the absence of a Keimbahn in plants, in the
sense in which it is known to be present in many animals.
The classical cases of Ascaris (Boveri) and Cyclops
(Häcker) need only be cited. More recently, other work,
such as that of Hegner (’09) iù the Coleoptera, has shown
that the germ cells are formed from certain free nuclei, at
an early stage in the segmentation of the egg. Thus set
aside, they rest and undergo very few divisions, until
a late stage of embryonic life. There is no evidence
whatever of a similar process in higher plants, and it is
probably made impossible by the method of plant growth.
On the other hand, it may be pointed out that while, in
plants, there are no resting cells set aside in the body
tissues, to serve later as reproductive cells, yet a lineage
of cells exists, which may be looked upon as a Keimbahn
in one sense. Every one who has studied plant embryos
recognizes their characteristically large nuclei with huge
nucleoli having a large chromatin content. A similar
appearance is characteristic of all undifferentiated
meristematic cells, so that such cells, forming a lineage
from the egg cell to the spore mother cells, may be
thought of as constituting a Keimbahn for the plant,
though evidently in a somewhat different sense from
that in which the term is employed for animals. The
fact that in such a lineage, a great number of cell genera-
tions intervene between the fertilized egg and the spore
mother cell, together with the fact that the meristematic
cells forming this lineage are near the surface of the
plant, where they are almost directly exposed to en-
vironmental influences (and not hidden away in the in-
No. 520] BASIS OF MENDELIAN PHENOMENA 211
terior of the body as in animals), doubtless accounts for
the greater plasticity exhibited by plants. Indeed, it is
a matter for wonder that, under these conditions, plants
show such hereditary constancy. The accurate repro-
duction, generation after generation, of the most minute
hereditary differences, shows the relative fixity of the
material of the germ plasm.
The work of the Marchals (’06 and ’07) with the
mosses seems to show clearly that, during the meiotic
divisions of spore formation, an actual segregation of
sex-producing tendencies or elements takes place. Much
other evidence of a similar sort in plants might be cited
if time permitted, and the case of the sex chromosomes
in insects is too well known to require more than mention.
But while the reduction divisions seem the most natural
place to look for an explanation of the Mendelian propor-
tions, yet on the other hand there is much evidence that
the phenomena of ‘‘splitting’’ also occur at other times
in the life history. Bateson (’05) has shown that in two
races of sweet peas (Lathyrus odoratus), one of which
has long pollen grains and the other round, the long
pollen character is dominant in the F,. If a segregation
of characters took place here during the reduction divi-
sions, we should find 50 per cent. of each type of pollen
grain. But plants having long pollen give only long, or
they may give three plants with long pollen to one with
round. Only in ‘‘very rare and exceptional’’ cases is
there a mixture of long and round in the same plant,
and in such cases they are found only in certain flowers
of an individual. Rosenberg (’06) found that in the
hybrid Drosera longifolia X D. rotundifolia, in some
cases two pollen grains of a tetrad resemble each parent,
the grains differing chiefly in size. More recently, how-
ever, he has found (’09) that the variations in the size
of the hybrid pollen grains probably depend upon the
numbers of chromosomes which enter the respective
daughter nuclei during reduction, and hence this differ-
ence in pollen grains will no longer serve as evidence for
a segregation of characters at this time.
There is nothing to indicate that the phenomena of
212 THE AMERICAN NATURALIST [ Vou. XLIV
vegetative splitting, or reversion to the parental types,
in such forms as the reputed graft-hybrid, Cytisus
Adami, differ in any essential respect from Mendelian
segregation in germ cells. In angiosperms, the great
majority of which are hermaphrodite, there is a separa-
tion of tendencies, which may be thought of as a ‘‘segre-
gation,’’ in the Anlage of every flower, the stamens pro-
ducing microspores and male gametophytes, while the
ovules bear the megaspores, which develop the female
gametophyte. These two tendencies—namely, for the
stamens to produce microspores and the ovules to pro-
duce the female gametophyte—are almost never inter-
changed (although Němec, ’98, has described a case in
Hyacinthus, in which the microspores may produce a
structure resembling more or less the female gameto-
phyte). Whether there is here a separation of substances
in the cytoplasm or chromoplasm during the division of
certain cells in the Anlage of the flower, is not known,
but it is not impossible that such is the case.
Viewed from this standpoint, all differentiation during
ontogeny may be considered a ‘‘segregation.’’ A con-
sideration of what this really consists in would involve
the whole great problem of individual development,
which I shall not touch upon here. But it may be pointed
out that maturation, particularly in Mendelian hybrids,
may be looked upon as a period of active germ cell dif-
ferentiation.
The factors involved in such differentiation may be,
in some cases, quite as complex as those involved in
development itself, but as I have shown from the evi-
dence of these Gnothera hybrids, and as appears from
color inheritance in mammals and from other evidence,
in many cases at least the difference between Mendelian
germ cells must be of a simple quantitative sort, involv-
ing either a difference in the amount of certain material
substances or a difference in the energy-content of cer-
tain constituents.
From this point of view, many instances of Mendelian
behavior are seen to be cases of quantitative inheritance.
No. 520] BASIS OF MENDELIAN PHENOMENA 213
LITERATURE CITED
Bateson, W., Saunders, Miss E. R., Punnett, R. C., and Hurst, C. C. 1905.
Report II. to the Evolution Conimittes of the Hoya sweet Experimental
studies in the physiology of heredity. London
Buscalioni, Luigi e Pollacci, Gino. 1904. Le EA ed ù loro significato
iologico nelle pane Atti dell’ Instituto Bot. univ. di Pavia, 2d Ser.,
1 =
Combes, R. 1909. Spee a rele sans | prams de la decorti-
cation annulaire. Bull. Soc. Bot. de France, 56: —231
9 Resor entre ia composés hy practice et la formation
de l’anthocyane. Ann. Sci. Nat. Botanique, 9: 275-303.
pep R. W. - 1909. The origin and early history of the germ-cells in
me Chrysomelid beetles. Journ. Morph., 20: 231-296, pls. 4.
Laparde, J. 1908. Sur le mechanisme physiologique de la coloration des
raisins rouges et de la coloration automnale des feuilles. Comptes
Rendus, 147: 993-995.
Marchal, Élie and Emile. 1906. Recherches expérimentales sur la sexu-
alité des eH chez les mousses dioiques. Mém. couronnés, Acad.
roy. de Belgi 1
—— 1907. Apoasecis et sexualité chez les mousses. Bull. Acad. roy. de
Belgique, 1907: patie
Mirande, M. 1907. Sur l’origine de l’anthocyanine déduite de 1’observa-
tion de quelques ate parasites des feuilles. Comptes Rendus, 145:
1300-1302.
Molliard, M. 1907. Action morphogenique de quelques substances organ-
iques sur les végétaux supérieures. Rev. gén. de Bot., 19: 241-291,
329-349, 357-391, pls. 8, 9, 10 and 13, ies 52.
—— 1909. Production expérimentale de tubercules blanes et de tuber-
— ia noir à partir de graines de Radis rose. Comptes Rendus, 148:
573-
Morgan, $. H 1909. A biological and cytological study of sex deter-
mination in Tog and ee ids. Journ. Exptl. Zool., T: 239-
Ps gs.
Němec, B. 1898. era den Pollen der Petaloiden autheren von Hyacin
thus orientalis L. Bull. Int. Acad. Sci. Bohême, 5: 17-23, pls. 1-2.
Overton, E. 1899. Beobachtungen und Vermsthen über das Auftreten von
othem Zellsaft bei Pflanzen. Jahrb. Wiss. Bot., 33: 171-231.
Palladin, W. 1908. Ueber die Bildung der Atmungschromogene in den
Pflanzen. Ber. Deut. Bot. Gesells., 26a: 389-394.
Pick, H. 1883. Ueber die Bedeutung gale rothem Farbstoffes bei den
Phanerogamen und die Beziehungen de: n zur starkewanderung.
Bot. Centlbl., 16: 281-284, 314-818, ais cur. 375-382, pl. 1.
peat Oscar. 1909. Our knowledge of Melanin color formation and its
ri on the Mendelian description of heredity. Biol. Bull., 16:
Sikes,
o O. 1906. Erblichkeitsgesetze und Chromosomen. Botaniska
aa oik 243, figs. 5.
— 3000. Cyt sche und morphologische Studien über Drosera longi-
folia venta X rotundifolia. — Svenska i caeead
Handl., 43: 1.
MENDELIAN PHENOMENA WITHOUT
DE VRIESIAN THEORY!
DR. W. J. SPILLMAN
U. S. DEPT. or AGRICULTURE
Tmar the phenomena of Mendelian segregation of char-
acter pairs is inextricably linked with the de Vriesian
notion of pangenes is an opinion widely held, both by the
advocates of the theory of discontinuous variation and by
the opponents of that theory. Professor S. J. Holmes
was one of the first American biologists to point out the
fallacy of this idea.? He called attention to the fact
- that due consideration of the phenomena reported by
Mendelian investigators did not lead to the theory of dis-
continuous variation as a necessary consequence.
While in the present paper it is my purpose to present
an explanation of Mendelian phenomena without resort-
ing to the idea of unit characters, I do not wish to be un-
derstood as belittling the important work done by de Vries
and his followers. While contending that the de Vriesian
doctrine that organisms are aggregates of separately her-
itable characters is unsound, I believe this investigator
-has uncovered a new type of variation which must be
reckoned with as a means of evolution, not by any means
the sole, or even the most important, means. For want
of space, I am compelled, in what follows, to present some-
opinions without submitting all the evidence in favor of
them. However, an attempt will be made later to present
this evidence more fully. It seems to the writer that |
what Darwin considered to be fluctuating variations,
amenable to the action of natural selection, may now be
regarded as consisting of four distinct types of variation.
First, we have those variations in the progeny of a given
individual, or pair of individuals, which are due to what
we may call ‘‘Mendelian recombination of characters.’’
1 This paper was presented before the American Society of Naturalists,
in Boston, Mass., December 29, 1909.
? See AMER. Nat; May, 1909.
214
No. 520] MENDELIAN PHENOMENA 215
Natural selection may have a very important influence
on variations of this kind, since the variations are heredi-
tary. The recognition of variations of this type must
of course be attributed to Mendel, but de Vries, Correns,
Von T'schermak and perhaps some others must be recog-
nized as rediscoverers of this principle.
In the second place, after we have eliminated all varia-
tion caused by Mendelian recombination we still have a
type of variation which is more and more coming to be
called fluctuation, and which is due wholly to environ-
ment. Such variations are now believed not to be hered-
itary and therefore not amenable to the action of natural
selection. In this connection we need only mention the
. important investigations of Johanssen on beans and bar-
ley,? the work of Nilssen and his able staff at Svalöf on
wheat, oats and other species, and the recent classic work
of Jennings on Paramecium. The work of these inves-
tigators indicates strongly that selection is without effect
on fluctuations due to environment. Dr. E. M. East, in
Illinois Experiment Station Bulletin No. 127, reaches
the conclusion that no effect of selection has been proven
in clonal varieties of potatoes.
In the third place, de Vries found a type of variation
which the cytological work of Gates,’ Rosenberg? and
Gager,” indicates to be due to irregularity in the distri-
bution of chromosomes in mitosis.
Gates has shown that in the species with which de Vries
worked there are irregularities in chromosome distribu-
tion. Furthermore, de Vries has shown that his mutants
differ from each other in almost every detail, just as we
should expect them to do if each of the chromosomes is
more or less responsible for the whole process of develop-
ment.
*W. Johannsen, ‘‘ Ueber Erblichkeit in Populationen u. Reinen Linien,’’
seme. hose 1903; Rep. 3d Int. Con. on Geneties, pp.
B, ings, Proc. Amer. Phil. Soc., XLVII, No. 190, 1908; Jour.
bie Soak: Vol 594, June, 1908.
R. R. Gates, Science, January 31, 1908; Science, February 12, 1909, and
rte
* O. Rosenberg, Rep. 3d Int. Con. on Geneties, pp. 289-29
1E. Stewart Gager, Publications of New York aula Garden.
216 THE AMERICAN NATURALIST [ Vou. XLIV
Rosenberg has shown that the irregularity of certain
first-generation Hieracium hybrids is accompanied by
irregularity in the number of chromosomes present.
Quite recently Gager,.in his study of the effect of ra- -
dium emanations on plants, has not only produced mutants
apparently of the character of those found by de Vries,
but has shown that in mitosis in treated specimens there
is irregularity in the distribution of chromosomes. The
writer some time ago suggested a similar explanation for
the interesting work of McDougall in which mutants were
produced by chemical stimulants. The behavior of the
Rubus hybrid produced by Burbank, and resulting in the
Primus berry, is so closely parallel to that of Hieracium
hybrids studied by Rosenberg that a similar explanation
at once suggests itself.
Boveri’s classic work on the relation of chromosomes
to development strongly supports the view that the de
Vriesian mutants are due to loss or exchange of chro-
mosomes, and this view is consistent with the work of
Wilson, Morgan, Stevens and others on the relation of
the chromosomes to sex.
I think, therefore, that we are in position to recognize,
at least tentatively, a new type of variation, which is due
to irregularities in the distribution of chromosomes, and
which I shall call ‘‘de Vriesian mutation.’? These varia-
tions, being hereditary, are amenable to the action of
natural selection, and must therefore be recognized as one
method of evolution. In a certain sense these mutations
are discontinuous, and the reason for this is apparently
clear.
When we consider all the facts in the case, which I have
not time here to outline, I think that few biologists will
contend that all evolutionary changes are due to Men-
delian recombination, or to de Vriesian mutation as de-
fined above. The enormous diversity in groups having
the same number of chromosomes, as well as observable
differences in the chromosomes themselves, render any
such view untenable. I therefore postulate a fourth kind
of variation due to fundamental changes in what we may
No. 520] MENDELIAN PHENOMENA 217
call the germ plasm, and I am inclined to believe that this
is by far the most important type of evolutionary change.
Whether changes of this character are continuous or dis-
continuous is not a very important question. It is more
important to ascertain their cause and nature. I imagine
they are largely chemical changes in the composition of,
or changes in the relative amounts of substances present
in, the germ plasm. _ If these changes are continuous the
work of Johannsen, Nilssen, Jennings and Hast, above
referred to, indicates that they are very slow. Such
changes are certainly hereditary, and are thus a factor,
and I believe the most important factor, in evolution.
One point regarding fundamental changes in the germ
plasm it is important to remember: a gradual change
might go on for a long time in the chemical activity of the
cell before reaching a point where any outward manifesta-
tion of this change would appear. For instance; in some
purple flowers there is reason to believe that the color is
due to some such action as that of acids and alkalies upon
the color of litmus, the flower being red or purple accord-
ing to the amount of some substance present. Now a
gradual change might go on in the relations between the
substances concerned without producing any visible effect
until a certain point is reached, when a marked effect is
produced, giving what appears to be a discontinuous
change, but what may be in reality a critical point in a
slow and gradual change.
Riddle, in his recent very interesting paper on melanin
color formation’ has shown that in all probability melanin
colors develop as the result of the action of an enzyme
upon a chromogen, and that this action is a complex one.
The chromogen is first converted into a new substance,
the same enzyme then converts this substance into a third,
and so on, producing a long series of substances. The
early numbers in this series give no color, but finally a
stage is reached where a number of steps in the series give
color. Riddle seems to think that all the melanin colors
found in organisms should be referred simply to the dif-
ê Biological Bulletin, May 1909, pp. 316-351.
218 THE AMERICAN NATURALIST [Vou. XLIV
ferent stages of a single process of oxidation. This, how-
ever, can hardly be true. The fact that we get two or
three kinds of pigment deposited in the same region of the
organism, apparently at the same time, would indicate
that there is more than one oxidation process involved.
Furthermore, Riddle himself points out that, while in
some oxidation processes series of colors occur extending
from light yellow to black, with reds and browns as inter-
mediates, in others the final stages of the oxidation proc-
esses are red. Quite a number of different oxidation
processes are cited. Now the facts of color inheritance
indicate that there may be several oxidation processes,
and that in some of them a given color, for instance, red,
appears as soon as color appears at all.
Assuming that the production of enzyme and chromo-
gen is a general function of protoplasm, and assuming
further that the relative amount of enzyme and chromo-
gen present have a determining influence on the stage
which the oxidizing process reaches in the organism, the
phenomena of Mendelian color inheritance are easily ex-
plained without recourse to the idea of unit characters at
all, as I shall now attempt to show. It must be under-
stood that the figures in the following tables are merely
illustrative and are not meant at all to indicate actual
amounts.
TABLE I
RED AND WHITE PEAS
RELATIVE CONTRIBUTIONS. Fi | Fa
Organs -
Pure Red. Pure White. BB BB’ BB
- Per cent. Per cent. Percent. | Percent. | Percent. | Per cent.
Cy 25 25 25 25 25 25
AA 15 15 15 15 15 15
BRB 30 10 20 30 20 10
8 8 8 8
DD etc 22 22 22 22 22 22
100 80 90 100 90 80
—
Red White | Red Red White
Let us consider first the cross between red and white
sweet peas, in which generation F, of the hybrid is red
and generation F, gives us the ordinary Mendelian ratio
No. 520] MENDELIAN PHENOMENA 219
of three red to one white. Table I shows an explanation
of the Mendelian results on the assumption that every
organ in the cell is concerned in color development. It is
assumed in this instance, merely for purpose of illustra-
tion, that when the amount of enzyme present in the cell is
85 per cent. or more of the amount found in pure red races
the oxidation process reaches the stage necessary to pro-
duce red coloration. The same end results would occur
if, because of some peculiarity of a single pair of chromo-
somes in the white race, as compared with the red, the
end result of the oxidation process in the white race Ces
no color.
In the first column of this table Cy represents the cyto-
plasm, and, in fact, all of the organs in the cell except the
paired chromosomes. AA, BB, etc., represent pairs of
homologous chromosomes. The second column gives as-
sumed relations between the amount, say, of the enzyme
produced by the different organs of the cell in the pure
red race. It is assumed, for instance, that all the organs
of the cell except the chromosomes produce 25 per cent. of
this enzyme. The first pair of chromosomes produce 15
per cent., the second pair 30 per cent., and so on.
Now, with the assumptions made, a white race would re-
sult if a single pair of chromosomes produce markedly
less of the enzyme than they produce in the red race.
Column 3 shows the hypothetical conditions in such a
white race. In the table it.is assumed that in the red race
the second pair of chromosomes produce 30 per cent. of
the total amount of enzyme present, while in the white
race, for some reason, this pair of chromosomes produces
only one third of the enzyme it does in the red. Thus, in
the white race we have only 80 per cent. of the amount of
enzyme present in the red, and not enough to carry the
oxidation process to the point of giving red coloration.
The hybrid between these two races will have one chro-
mosome producing its 15 parts and another chromosome
producing only 5 parts, thus giving 20 parts where in the
red | race we had 30. In all, there is in the hybrid 90 AE
220 THE AMERICAN NATURALIST [ Vou. XLIV
cent. as much of the enzyme as in the pure red. With the
assumptions made the hybrid would therefore be red.
It is well known that heterozygotes frequently present
vegetative vigor much greater than that of the related
homozygotes. This may be possibly due to the greater
opportunity certain chromosomes have of making more
growth before filling the cell with their products. If such
is the case, then the enzyme produced in our hybrid might
exceed the mean between that produced in the two races
crossed. This would explain the preponderance of cases
in which the heterozygote resembles that parent which
represents the more advanced ontogenetic stage. But
there are not a few cases in which the heterozygote re-
sembles the other parent. This happens to be the case in
two of the first cases of dominance made out by the
writer; namely, beards in wheat and horns in cattle.
Both of these characters are recessive; or, as the de Vries-
ians would say, in them, absence is dominant to presence.
Under the present hypothesis, we do away entirely with `
the presence and absence hypothesis, as will be seen later.’
In generation F, (Table I) one fourth of the progeny
would possess a pair of chromosomes each of which pro-
duces its 15 parts of enzyme. One half of the individuals
would have one chromosome producing 15 parts and an-
other producing 5, while the remaining fourth of the in-
dividuals would have a pair of chromosomes each of
which produces only 5 parts. We thus have one fourth
of the population producing the normal amount of
enzyme, half of it producing 90 per cent. of this, and one
fourth of it producing only 80 per cent. This would give
us three red individuals to one white.
It must be remembered that I am merely attempting to
show here that it is possible to make assumptions that
will explain Mendelian phenomena without resort to the
idea of unit characters.
In Table IT we have a more complex case; namely, that
of the cross between red and white Antirrhinwms reported
by de Vries. In this cross de Vries found what is ordi-
- *See'article by Shull in American Narorauisr, July, 1909.
No. 520] MENDELIAN PHENOMENA 221
narily called two pairs of Mendelian characters. Under
the assumptions I have made this simply means that in
the white race there are two pairs of chromosomes which
were deficient in the amount of enzyme produced as com-
pared with the pure red race used by de Vries in this
cross.
TABLE II
RED AND WHITE ANTIRRHINUMS
RELATIVE CONTRIBU- | F} | Fo
TIONS. |
Organs. | ld 1b Ss 1 S| RIRIS
Pure Red. Pure White. Š 2 è] ` | Š Shala] S
| BE fe Pes Bal aN ett
ee as EACLE ee eee.
Cy 24 | 94 [H] 24/24) 24] 24 | 24 | 24 | 24 | 24 | 24
AA 30 | 14 (23) 30/30/30) 22 | 22 | 14| 14 | 14
BB R orp 12| 12|12|12| 12 | 1a 12 | 12 | 12 | 12
CC 26 22 |24| 26/24/22! 26 | 24 | 22 | 26 | 24 | 22
DD ete ge 8 8| 8| 8} 8| 8| 8 8| 8| 8 8
100 | 80 (90/100 $8 96 92 90 88 | 84 8 82 80
Red | White IR) Red | Del. yes
In the third column of Table II we have 14 parts of en-
zyme instead of 30 in the second column (chromosomes
AA), and 22 parts instead of 26 in the second column
(chromosomes CC). Since the hybrid gets one of each
pair of chromosome from each of the parents it has 22
parts instead of 30, and 24 instead of 26. If, in this case,
the amount of enzyme present in the cell is 85 per cent., or
more of that present in the original red race with which
de Vries worked, it is assumed that the oxidation process
will reach the red stages. The hybrid in this case is red,
though perhaps not so deep a shade of red as the pure
red race.
In generation F, of this hybrid we have nine types.
The first type is like the pure red race with which de
Vries started. The third of these types is another pure
race, but with a lessened amount of enzyme, and presum-
ably less intense red color. The seventh type is also a
pure race, but it is one which had only a little red at the
margins of the petals and a type to which de Vries gave
the name Delilah. The ninth type is also a pure race,
222 THE AMERICAN NATURALIST (Vou. XLIV
which has white flowers and is like the pure white parent
used in the cross.
De Vries states that in the reds and the Delilahs found
in F, there was a good deal of variation, which is what
we might expect from the relations shown in Table II,
but he was able to group them, as shown at the bottom
of Table II, and get the usual Mendelian ratios.
I have assumed here that when the enzyme is present in
proportions from 82 per cent. to 84 per cent. of that in the
pure red race, we get the Delilah type. This merely means
that in the Delilah types the amount of enzyme present is
near the critical point for the production of red color.
There seems to be no question that the environment in
the organism itself is a very important determining factor
in the development of any character. It is not therefore
fanciful to assume that in view of the fact that we get
color development only in the petals the tendency to color
development might be greater in one part of the petal than
in another. We thus see that our assumptions are in
agreement with the facts of inheritance made out by de
Vries.
CRYPTOMERIC CHARACTERS
In one of Bateson’s Matthiola crosses,’° between a
cream-colored and a white race, he found that the first
cross was purple and that amongst its progeny it pro-
duced purples, reds, creams and whites. He explained
these phenomena by assuming that red is due to two
eryptomerice factors which are ineffective unless present
in the same cell, while purple was due to a third factor
which converted red into purple and which was found in
the white variety. These phenomena may be brought in
line with our hypothesis, as shown in Table ITI.
In this case we evidently have to deal with more than
two chemical substances. For the production of the red
character itself two of these substances are necessary.
It is, of course, possible that in the simpler case consid-
ered earlier the same two substances, possibly others also,
» See Rep. III, Evolu. Com., Roy. Soc., 1906.
No. 520] MENDELIAN PHENOMENA 223
are responsible for red, but, there being a deficiency in
only one of them, we get the phenomena considered in
Table I.
TABLE III
CRYPTOMERIC CHARACTERS
Bateson’s Matthiola Crosses
= first factor for red; R, = second factor for red.
= factor for purple. R, and R, produce red when present in greater
Mides than 90 per cent. of normal amount in pure purples
P converts red to purple when P is present in 90 per ect. of normal
amount in pure purples.
Cream var. | White var. | F,
Organs. i | | SNR
Rig Pe RS ee or ak tome
4 4 oe ee a
Cy Ý á|á 16 ct bk ol 18 | a ee
AA | 12 | 2% | 26 28 | 26 26 20 | % | 2%
BBR | 44-1 16°) 233 14 16 12 14/16 | 12
O | 22 | 20 | 22 22 2| 2 RA
DD | 18 | 18 0 Py ee 8 1% | 18 | 18 | @
pauio oe eas ee et ee a
In the cross now under consideration we must assume
that, taking the cream and the white races collectively,
there are deficiencies in two substances necessary for the
production of the red, as well as in the substance neces-
sary for the production of the purple, or in one of the
substances if more than one is necessary.
‘Let R, represent the first factor for red, R, the second
factor for Red, and P the factor for purple. It is as-
sumed that when either R, or R, is deficient to the amount
of 10 per cent. of the amount of these substances found
in pure purple races, the reactions will not reach the
stage necessary for the production of red color, and that |
when there is a like deficiency in the substance necessary
for transforming red into purple this transformation
does not occur.
Column 2 of Table III shows the contribution of each
of the cell organs to the substance R, in the cream va-
riety; the next column gives similar data for substance
R., and the next for the purple factor. The facts indi-
cate that there is a deficiency in one pair of chromosomes
(AA) for the substance R, in the cream variety; also for
224 THE AMERICAN NATURALIST [ Vou. XLIV
the purple factor in another pair of chromosomes (DD).
These deficiencies are italicized in the table. In the
white variety there is assumed to be a deficiency for the
substance R, in a third pair of chromosomes. These as-
sumptions give the phenomena found by Bateson. A
similar case is found in sweet peas."
It is seen in Table III that the cream variety has less of
R, than is necessary to produce red coloration. It also
has less of the purple factor than is necessary for con-
verting red into purple, while the white variety has less
of the substance R, than is necessary for the production
of red.
Generation F, will have enough of all these substances
to produce red and to convert red into purple.
The second generation of this hybrid contains 27 types.
I will not here go into detail concerning that generation,
but will merely add that the assumptions made are con-
sistent with the facts observed in the second generation.
TABLE IV
. HETEROZYGOTE CHARACTERS
Spotted F, beans from non-spotted P,’s.
Sı = first factor of spotting; S,—sec. factor of spotting. S, and S,
assumed to become operative when present in greater proportion than 85
per cent. of normal in pure spotted beans.
ĝ Parent. Ọ Parent. F,
Organs.
S, Sa A. Sa S, Sa
é P 6 P a 4
Cy 40 30 40 30 40 30
AA 36 22 16 42 26 32
BB etc. 24 28 24 28 24 28
100 s | %0 100 90 90
Table III deals with cryptomeric characters which are
seen to owe their development to the reaction between
two, or possibly more, chemical substances, the production
of each of which is a generalized function of the cell. It
is, of course, possible that each of these substances is
produced only by a single chromosome, which case would
be merely a limiting case in which all the cell organs ex-
™ Rep. III, Evolu. Com., Roy. Soe.
No. 520] MENDELIAN PHENOMENA 225
cept one produce none of a given substance in question.
Table IV deals with that class of characters which
appear in heterozygotes, but not in pure races. Loche,
Von Tschermak, Shull and Emerson have all studied such
a character in beans. In certain crosses between beans
not having spotted seeds the heterozygotes were spotted.
Let us assume that the development of spotting on the
seed coat is due to certain metabolic activities that in-
volve at least two substances the production of which is
either a generalized function of all cell organs or is a
function of at least one pair of chromosomes. Let S,
represent one of the substances necessary to these reac-
tions, and 8, another. Further, let us assume that in
order to bring about the conditions necessary for the reac-
tion both S, and S, must be present in a proportion 85
per cent. as great as in pure races of beans with spotted
seed coats. In one of the races we assume a deficiency
of substance S., and we assume that this deficiency is
found in one pair of chromosomes only. In the other
race there is a deficiency in substance S,, and the same
pair of chromosomes is responsible for this deficiency.
Column 3 of Table IV shows 80 per cent. of the amount
of S, found in ordinary spotted races of beans, while
column 4 shows a similar deficiency in the substance S, in
the other race.
Now generation F, of this cross receives one of the
chromosomes in question from each of the parents, and
in the case of each substance there is a deficiency of
only 10 per cent. This gives us a spotted seed coat.
In the second generation, which is not shown in the
table, one fourth of the progeny would be like the male
parent and the other fourth like the female parent, neither
of which has spotted seed coats, while half of the progeny
would be like F, with respect to spotting of the seed coat.
While in this discussion it has been assumed that each
of the substances with which we dealt was produced as
the result of a general function of protoplasm, this is
not necessarily the case. When we consider the history
of the chromosomes it would appear very reasonable to
226 THE AMERICAN NATURALIST [Von XLIV-
suppose that marked variation in the composition, and
consequently in the functions, of the chromosomes may
have occurred as a result of evolutionary changes. It
may be that some of the substances with which we have
dealt are produced only by particular chromosomes, but
we can hardly decide this question with the evidence at
hand. In any case, particular chromosomes must be re-
sponsible for the deficiencies of the substances in order to
get Mendelian phenomena. As previously stated, my
object is simply to show that it is possible to make as-
sumptions that will give us Mendelian phenomena without
unit characters. The assumptions made seem to be con-
sistent with the facts of physiological chemistry.
Even if we assume that the various substances with
which we have been dealing are each produced by a single
pair of chromosomes rather than by all the organs of the
cell we can not look upon the chromosomes as the heredi-
tary units spoken of by the de Vriesians and Weismann-
ians, for we here look upon each chromosome as play-
ing possibly an important part in the development of
every feature of the organism.
The fact that in some species the number of pairs of
Mendelian characters found is greater than the number
of chromosomes is not an argument against the validity
of the assumptions I have made. In Table IV we have
assumed that the same pair of chromosomes may be re-
sponsible in one race for the deficiency of a certain sub-
stance and in another race for the deficiency of another
substance. It happens in this case that the two sub-
stances concerned are both necessary to a particular reac-
tion. If each chromosome play its part in the develop-
ment of all parts of the organism, we might, in different
races of a species, have a good many Mendelian characters
dependent upon the same set of chromosomes, and in-
stances of this kind are not wanting. For instance, Bate-
son found a particular flower color and a particular shape
of the standard in sweet peas to be alternative to each
other in inheritance. In other words, in the terms of our
theory we have here two pairs of Mendelian characters
No. 520] MENDELIAN PHENOMENA 227
based on the same pair of chromosomes. Several other
similar cases are known. So that in order to prove that
anything smaller than a chromosome is responsible for a
Mendelian character difference it must be shown that we
can get into a single individual more independent Men-
delian character pairs than it has pairs of chromosomes.
Both Baur and Shull, in private correspondence with the
writer, have admitted the justice of this contention, and
have promised to put it to the test.
Under the present hypothesis what has heretofore been
called a pair of Mendelian unit characters must have a
new name. For instance, in the red and white pea cross,
if our assumption regarding the cause of the Mendelian
phenomena is correct, we are not dealing with a pair of
characters at all in the de Vriesian sense. Red is as-
sumed to be a generalized function of the cell, and white
likewise, but the difference between the red and the white
concerns a single cell organ, and it is this difference with
which we are dealing. Dr. McDougal, in conversation
with the writer on this point a few days ago, suggested
that in discussing this hypothesis we use the term ‘‘char-
acter differential’’ instead of character pair, and the sug-
gestion seems to-be a good one. We do, however, need
a few terms, which I shall now proceed to introduce
Under our hypothesis each of the organs of the cell is
supposed to have various functions in development. One
function may relate to the development of a particular
character, and another to a very different character.
Furthermore, several or all the organs in the cell may
each have a function relating to the same character.
But not only are the organs of the cell supposed to play
their part in development, but various organs, tissues and
substances produced in the organism during development
may also have functions which play a part in the develop-
ment of various portions of the organism. For instance,
hairs normally develop only in the skin. Hence the skin
itself influences the development of hair. It is supposed
that certain substances, called hormones, may materially
affect the development of parts of the organism widely
228 THE AMERICAN NATURALIST [ Vou. XLIV
separated from the part of the organism in which these
substances are produced. Thus the greater development
of horns in the males of certain species is supposed to be
due to hormones produced in the testes.
Any organ, tissue, substance or cell organ which thus
has the power of influencing the course of development,
I propose to call a ‘‘teleone.’? This word is from the
Greek teleo, which means make, or accomplish. 'Teleones
occurring in the egg, and presumably derived directly
from the previous generation, may be called primary
teleones. Those that arise during the course of develop-
ment may be called secondary teleones. The manner in
which primary teleones function in heredity has already
been indicated. In a simple Mendelian character differ-
ence we are thus dealing, not with two unit characters,
nor with the presence and absence of a single unit char-
acter, but with a difference between two teleones.
Under this hypothesis, transmission becomes, not the
transmission of characters as such, but the transmission
of cell organs having functions which determine character,
or which influence development. This hypothesis may
properly be called the teleone hypothesis.
A word about species crosses. We may imagine that,
in species not closely related, the corresponding teleonic
functions all differ more or less; hence we should not ex-
pect many simple Mendelian phenomena in such crosses.
Again, in wide crosses, it will probably happen frequently
that the chromosomes brought together will be so dis-
similar that they do not act together in the usual manner,
especially in the reduction division. We should expect
Mendelian phenomena only in cases where homologous
chromosomes go through synapsis and reduction in a
formal manner.
Finally, when character differentials relate to anything
other than chromosomes, Mendelian splitting should not
occur. I would therefore suggest that some of the char-
acter differentials studied by Castle in rabbits are due to
cytoplasmic differences, or at least are not due to the
chromosomes.
THE EVOLUTION OF NEW FORMS IN VIOLA
THROUGH HYBRIDISM?!
PROFESSOR EZRA BRAINERD
MIDDLEBURY, VERMONT
Dvurine the past eight years I have given much time to
the study of our North American violets, not only as rep-
resented in large herbaria, but especially as seen in living
specimens, both in their natural surroundings and under
culture. My garden now contains over 3,500 violet plants
of about 650 different numbers or sorts, some 200 of which
are from the wild, and 450 raised from seed.
The genus has for over a century been known as diffi-
cult and perplexing because of its polymorphism. It has
been my good fortune to discover that this is largely due
to the frequent occurrence of hybrids between species of
the same group. I make out to date some 66 different
hybrids that have arisen spontaneously. From about 50
of these I have raised offspring that segregate, often in a
surprising manner, reverting variously to the characters
of the putative parents of the hybrid. In many cases I
have raised from the hybrid two, or even three, genera-
tions of offspring.
But not all the anomalous violets that I have grown and
propagated can be called hybrids. Hybrids in Viola may
be known by two marks: first, they are either completely
sterile or markedly infertile; secondly, their seedlings are
strikingly unlike each other, and often unlike the mother
plant. The other class of anomalous violets are normally
fertile, and come true to seed; they are often of sporadic
occurrence, or if appearing in two or three stations, the
stations may be hundreds of miles apart; furthermore,
they usually present a mixture of the characters to be
1 This paper was presented before the American Society of Naturalists,
in Boston, Mass., December 29, 1909.
229
230 THE AMERICAN NATURALIST [Vou. XLIV
found in some two of the species with which they grow.
These odd forms, of which I have noted nearly a hundred,
are, in my opinion, largely the result of hybridism in the
remote or recent past. The detailed evidence of this can
not be presented in a twenty-minute paper; it demands a
printed essay with abundant illustration. I shall here
attempt only a brief summary of methods and results.
I would first call attention to the transitory existence of
a hybrid, especially when self-fertilized, as is usually the
ease in Viola. This follows from the laws of Mendel as a
mathematical corollary, though I am not aware of any
paper in which these deductions have been clearly set
forth. Mendel, indeed, showed that in the case of the
monohybrid (where the parents differ in only one char-
acter) the offspring in the first generation are one half
stable, in the second three fourths stable, in the third
seven eighths, and so on; until in the tenth generation
there is on the average only one hybrid in 1,024 plants.
But it can be proved that where the parents differ in
two characters there will be on the average in the tenth
generation only two hybrids in 1,024 plants; where the
parents differ in three characters, there will be less than
three hybrids in 1,000 plants: where they differ in four
characters, less than four hybrids in 1,000; and so on. In
the ordinary hybrid over 50 per cent of the offspring in
the fourth generation will be stable; in the sixth genera-
tion over 85 per cent will be stable; in the eighth genera-
tion over 95 per cent; in the tenth generation over 99
per cent. The life of the self-fertilized hybrid is there-
fore always precarious and relatively brief. The organ-
ism is in unstable equilibrium, and is rapidly shifting into
conditions of stability.
‘But the stable forms that emerge are not, as a rule, the
forms found in the parents of the original hybrid. They
are exclusively such only in the case of the monohybrid;
in hybrids of a higher grade the stable forms consist of all
possible recombinations of the opposed characters of the
parent species. Two species that differ in six characters
No. 520] EVOLUTION IN VIOLA 231
are capable when crossed of giving rise to 64 distinct and
stable forms; if they differ in eight characters, of giving
rise to 256 stable forms; if in ten characters, of giving rise
to over 1,000.
One or two particular cases must suffice to illustrate
how new and stable forms are artificially produced by the
propagation of hybrid offspring. In September, 1905,
with Mr. Witmer Stone, of Philadelphia, I visited Ivy
Hill Cemetery, an interesting violet station, from which
the previous May he had sent me several anomalous forms
of Viola. Two of these proved to be hybrids of a species
since named V. Stoneana; one with V. papilionacea, and
the other with V. triloba. V. Stoneana has palmately
dissected leaves and light-yellow seeds; V. papilionacea
has undissected leaves, and dark-brown seeds. Among
the progeny of their hybrid has appeared a form with the
undissected leaves of V. papilionacea and the light-yellow
seeds of V. Stoneana. This form comes true to seed (as
was to be expected, since both characters presented are
recessive), and shows no longer any marks of hybridity
or infertility. Thus has appeared in the garden a stable
variety of V. papilionacea with light-yellow seeds.
In the second hybrid, V. Stoneana X triloba, both par-
ents have dissected leaves, though of unlike pattern; but V.
triloba differs from V. Stoneana in being markedly pubes-
cent. The first sowing of the hybrid seed gave me only
four plants, one quite glabrous, three quite pubescent.
Seeds of these were sown the following year, and from one
of the three pubescent plants were obtained nine off-
_ spring, all pubescent with the leaf-form of V. Stoneana.
So here we seem to have a pure dominant—a stable ex-
hybrid—a new and pubescent variety of V. Stoneana.
Just such a plant was once sent me by Mr. House, col-
lected in the vicinity of Washington.
Leaving now the many cases of dehybridization in
Viola, that have arisen in a few years of garden culture,
let us glance at the evidence that this same process is
going on in a state of nature, and has probably been going
on for centuries. -
232 THE AMERICAN NATURALIST [ Vou. XLIV
Viola cucullata is a well-marked species of wide distri-
bution, but it exhibits many anomalous forms; or as some
would say, it is ‘‘an aggregate species.’’ The capsules are
a clear green in the numerous specimens that I have seen,
with one exception. A plant, sent me by Miss Ryon from
East Lyme, Conn., has dark-purple capsules; it is quite
fertile, breeds true to seed, and in all respects but capsule
color is normal V. cucullata. How shall we account for
this aberrant form? Fortunately, with this plant was
sent also from the same colony a hybrid of V. cucullata
X sororia. The latter species at this station, as often
elsewhere has very dark-purple capsules; may we not
reasonably believe that the purple-fruited V. cucullata
is a Mendelian product of the hybrid with which it was
growing?
Viola cucullata is normally a very glabrous plant. But
I have received forms of V. cucullata that were decidedly
pubescent, from three widely separated stations: Mt.
Mitchell, N..C., Milwaukee, Wis., and Salamanca, western
N. Y. The plant from Wisconsin has a roundish leaf that
resembles that of V. sororia, a pubescent species found at
the same station. It is quite likely, therefore, that both
the leaf-outline and the pubescent peduncles of the aber-
rant plant have come about through a former cross be- `
tween the two species.
In October, 1906, I received indirectly from Miss Mul-
ford, of Hempstead, Long Island, a plant of V. affinis
that had black seeds. The species, which is as wide-
spread as V. cucullata, has normally pale-yellow seeds.
I noticed that the black seeds of Miss Mulford’s plant
were also somewhat larger than the ordinary yellow seeds
of V. affinis. A careful weighing of 200 well-dried seeds
of each lot shows the black seeds to be 49 per cent. heavier
than the yellow seeds. I surmise, therefore, that the
anomalous form is a by-product of V. affinis X papilion-
acea, a hybrid from which I have obtained forms in the
garden similar to Miss Mulford’s. I should add that
though the black seed-color is dominant over the pale
No. 520] 7 EVOLUTION IN VIOLA 233
yellow, two generations of offspring from the Mulford
plant show the black color to be stable. ,
Just the opposite effect has been brought to pass in cer-
tain plants of V. nephrophylla, a northern species rang-
ing from eastern Quebec to the Rocky Mountains, and
having black seeds in all the many specimens seen, ex-
cept the one here discussed. This plant with buff seeds
appeared in a parcel of V. nephrophylla sent from Lake
Nemahbin, Wis., in 1907, by Dr. Ogden, of Milwaukee. The
plant was in all other characters good V. nephrophylla;
the capsules were crowded with seeds which for two gener-
ations have in turn produced plants with like buff seeds.
Now from the same region Dr. Ogden sent me a few days
later the hybrid V. affinis X nephrophylla, seeds from
whick the following year gave plants with buff as well as
with black seeds. It is therefore probable that the fertile
and stable buff-seeded V. nephrophylla from Lake Ne-
mahbin is the descendant of a hybrid of this species with
buff-seeded V. affinis.
Many similar cases have come under TE In
a limited region in Salisbury, Vt., of less than a square
mile, there occurs not iofragnentiy a very pubescent form
of V. latiuscula, a species which in all other stations I
have found to be quite glabrous. On the other hand,
from three stations I have obtained perfectly glabrous
plants of V. palmata, a species normally pubescent. The
plants from two of these three stations were somewhat
infertile, thus betraying their hybrid origin.
The effect of hybridism is plainly to be seen in the nu-
merous intergradient forms that occur between closely al-
lied species of Viola. Take, for example, V. fimbriatula
and V. sagittata, merged into one species by Dr. Gray,
probably because of this intergradience. The extreme
forms differ chiefly in three particulars: the leaf-blade of
V. sagittata is narrowly lanceolate, glabrous and coarsely
toothed at the base; that of V. fimbriatula is oblong-lan-
ceolate, pubescent and not coarsely toothed at the base.
But not infrequently we find colonies of Viola fimbriatula
234 THE AMERICAN NATURALIST [Vor. XLIV
with leaves that are coarsely toothed at the base, and col-
onies of V. sagittata with decidedly pubescent leaves; in-
deed, this is the prevalent form in the middle west.
Where the two species grow together, these and various
other interchanges of characters are frequent, in accord-
ance with Mendelian principles of segregation. A like
interchange of characters is noticeable in the stemless
white violets, V. blanda, V. renifolia and V. incognita;
and also in the stemmed yellow violets, V. pubescens and
V. scabriuscula.
We often find in species of wide distribution, as for
example V. affinis or V. papilionacea, numerous forms
distinct in one or more characters. Those who are so in-
clined can break up any one of these species into a dozen
or more ‘‘elementary species,’’ as some European botan-
ists have done with V. tricolor. But there are also cer-
tain species of Viola that are not polymorphic though of
‘fairly wide distribution; for example, V. rotundifolia, V.
Selkirkti, V. hastata; and it is worthy of note as bearing
upon the thesis of the present paper, that these species
have never been found to hybridize.
It frequently happens that a subhybrid form in Viola
is so unlike either parent of the first-cross as to appear to
be specifically distinct. Many such violet hybrids have in
recent years been named and published as species: V.
Mulforde Pollard, V. notabilis Bicknell and V. aber-
rans Greene are examples. It is surely hazardous in our
present knowledge of the genus to put forth as a species
a newly discovered form of Viola, without studying it
through at least one season of growth and through one
generation of offspring. It may, indeed, transpire that
the new form, though of hybrid origin, is distinct and
stable; and if fairly wide-spread, it may be entitled to
specific or varietal rank. The bar sinister in the eseutch-
eon of its bastard ancestry may have been quite oblit-
erated. We may be here witnessing the birth of a new
species through hybridism. Allow me in closing to pres-
ent an instance that makes a close approach to these con-
ditions.
No. 520] EVOLUTION IN VIOLA 235
In May, 1906, Mr. Stone sent me from Tinicum, Pa., a
living violet plant that was quite fertile and appeared a
good species. I could not make it out a hybrid, though
perhaps predisposed at that time to place an anomalous
form in this category. For further light I visited the sta-
tion with Mr. Stone the following September; but the
most careful search failed to reveal another specimen.
It soon afterward occurred to me that it might be an off-
spring of V. affinis X sagittata, a hybrid which I had
found at the same place the year previous, and had trans-
ferred to the garden. The two plants, mother and sup-
posed daughter, appeared much unlike, the former being
quite infertile, and in most respects an excellent interme-
diate between the putative parents that grew near by. But
careful examination showed that, though no one character
of the supposed daughter was intermediate as in the
mother, yet all were to be found in one or the other of the
supposed grandparents. The leaves had the breadth and
the rounded basal lobes of V. affinis, but the length and the
attenuate apex of V. sagittata; the capsules were pubes-
cent as in V. affinis, but green and large as in V. sagit-
tata; furthermore, the peduncles were strictly erect as in
V. sagittata, not ascending as in V. affinis; and also the
seeds were brown as in V. sagittata, not buff as in V.
affinis. : :
The next move was to raise offspring of the plant, to
discover if some one of these characters was not impure
—in other words, dominant and holding latent the op-
posed character. The 23 plants subsequently raised
showed all the characters of the plant under investigation
to be pure excepting two, the pubescence of the capsules
and the dark-brown color of the seeds; for glabrous cap-
sules and buff seeds appeared in some of the offspring.
The ratio of the four Mendelian forms in the 23 plants was
12: 4: 4: 3, or 9: 3: 3: 24, an unexpectedly close approx-
imation to the theoretical ratio 9: 3:3: 1.
From eleven of these plants another generation of 204
plants was raised the past season. Among these, in addi-
230 THE AMERICAN NATURALIST [ Vou. XLIV
tion to the five possible hybrid forms, were obtained also
the four possible stable forms. So that I now have fer-
tile plants, free of all hybridity, of four sorts, viz., 18
with pubescent capsules and dark seeds, 9 with pubescent
capsules and buff seeds, 18 with glabrous capsules and
dark seeds, 44 with glabrous capsules and buff seeds.
Surely, what I have done in the garden, nature might
do in the wild, thus evolving a distinct species with three
varieties.
In justice to my subject let me say that I am far from
maintaining that hybridism is furnishing in the genus
Viola all the new forms for natural selection to work
upon. Hybridism adds no new character to a group of
species; it simply recombines in multifarious ways char-
acters already existing. However numerous the patterns
that appear in the revolving kaleidoscope, their number
is limited; and if we looked long enough we should find
them substantially recurring from time to time. To get
a strictly new pattern, we should need to insert in the
apparatus a new fragment of colored glass. In the evolu-
tion of living organisms the new piece of colored glass is
what the biologists are considering under the name of
mutation.
TERTIARY ARCHHELENIS
DR. A. E. ORTMANN
CARNEGIE Museum, PITTSBURGH, Pa.
THe Archhelenis-theory of von Ihering has now re-
ceived so much support from various sides that we may
regard it as firmly established with regard to its general
correctness. Stated in broad terms, this theory assumes
a former land connection between Africa and South
America, which is rather old. This connection is the last
remnant of a large southern continental mass (South
Atlantis, Gondwana-land), which existed since the be-
ginning of the organic history of the earth (Cambrium),
which was broken to pieces at different times, and the
remnants of which are now found in Australia, India,
Africa and Brazil. The separation of Brazil from Africa
was the last step in the dismemberment of this old con-
tinent, an event which is placed by most writers toward
the end of the Mesozoic era, although some have admitted
the possible continuation of Archhelenis into the begin-
ning of the Tertiary.
Recently, von Ihering has tried to fix the time of the
disappearance of the connection between Africa and
Brazil more exactly, and arrived at the conclusion that
Archhelenis persisted at least through the Eocene. He
discusses the question chiefly in connection with his
studies on the marine fauna of the Patagonian beds,
which he regards as Eocene.! Comparing this fauna with
the contemporaneous Tertiary faunas of the rest of the
world, he discovers certain facts, which, according to
him, ean not be explained except by the assumption that
Archhelenis was still in existence at the beginning of
the Tertiary.
1 Ihering, H. von, ‘‘Les Mollusques fossiles du Tertiaire et du Crétacé
supérieur de 1’Argentine,’’ Anal. Mus. Buenos Aires, 14, 1907.
237
238 THE AMERICAN NATURALIST [Vou. XLIV
I fully aecept the facts of the faunistic relations of the
Patagonian beds, as laid down by von Ihering. Yet I do
not believe that they demonstrate the necessity of assum-
ing the existence of Archhelenis at that time, but, on the
contrary, I believe that they point just to the opposite,
namely, that at the time when the Patagonian beds were
deposited (in the early Tertiary—it does not matter, for
the present purpose, whether we regard the beds as
Eocene or younger) the connection between Brazil and
Africa must have disappeared, and that there must have
been a deep ocean in its place.
Of the relations of the Patagonian fauna to other
faunas, the following are mentioned by von Ihering as
most important (p. 76 ff.). |
While the Patagonian fauna in general is very peculiar,
and consists preeminently of southern (antarctic) ele-
ments, yet there are certain affinities to Tertiary faunas
of the northern hemisphere. But there are hardly any
relations to North America, and the few affinities with
northern faunas are rather with the Indo-European
fauna. This, of course, means that the Indo-European
forms, which may be regarded as constituting resem-
blances with the Patagonian fauna, are not found in
North American Tertiaries. Von Ihering believes that
these peculiar conditions are to be accounted for by the
existence of a land barrier between the North and the
South Atlantic, which prevented a migration of North
American marine forms to Patagonia, while there was a
possibility for Patagonia to receive Indo-European types
from the Indian ocean along the eastern coast of Africa
and the southern coast of the Atlantic land-connection
(Archhelenis).
While I do not doubt the correctness of the view that
Patagonia did not receive the Indo-European elements
of its fauna by the direct way, from the Mediterranean
across the Atlantic, I think, the fact of the absence of
these forms from North America is not correctly under-
stood and interpreted by von Ihering. If Archhelenis
No. 520] TERTIARY ARCHHELENIS 239
existed at that time, there must have been a coast line
not only in the south, but also in the north of this land,
running across the present Atlantic from North Africa
to the West Indies. Since the forms under discussion
are most emphatically marine littoral-shells, such a coast
line would have favored their migration from the Euro-
pean waters to those of the West Indies and North
America. Thus these forms, which are found both in the
Patagonian and in the Indo-European Tertiaries, should
have been able, by all means, to reach also North Amer-
ica. The fact, however, that they are absent in the latter
parts indicates decidedly, that there was no possibility
for them to go across the Atlantic from Europe to Amer-
ica, and thus there can not have been a coast line or a
land connection between Africa and South America, but
there must have existed a deep ocean (the Atlantic),
which prevented their migration from Europe to North
America as well as from Europe by the direct way to
Patagonia.
One fact, however, remains now unexplained, namely,
the absence of North American types in Patagonia. If
the Atlantic Ocean extended uninterruptedly from
north to south, as it does now, there must have been, dis-
regarding small interruptions at Panama and in the
region of the Amazonas, a rather continuous shore line,
along which the northern forms could have migrated to
Patagonia. I think such a north-south migration actu-
ally took place, but it did not reach the southern extrem-
ity of South America on account of climatic differentia-
tions along this coast line. Von Ihering points out (p.
492) that the Patagonian fauna is characterized by the
absence of certain types of shells, which are preeminently
tropical. This very strongly suggests that the Patago-
nian Tertiary seas were not of a tropical, but of a sub-
tropical or even temperate, character. If this is true, it
is apt to furnish an explanation for the absence of North
American forms in Patagonia. The North American
fauna of the Tertiary is found from Florida to New
240 THE AMERICAN NATURALIST [ Vou. XLIV
Jersey, and some of the richest deposits are in Florida
and Alabama, parts which surely had a tropical climate
in the beginning of the Tertiary. If Patagonia was ex-
tratropical, we can not expect that this fauna should
have reached it, for its southward migration would have
been stopped by the southern boundary of the tropical
belt.
On the other hand, von Ihering points out that, while
there was no immigration of tropical West Indian and
North American types during the Patagonian time, such
an immigration took place later, when the Entrerios beds
were deposited (which he believes to be Miocene), for we
find such forms in these beds. He thinks that it is thus
demonstrated that the destruction of Archhelenis falls in
the time between the deposition of the Patagonian and
Entrerios beds. I can not admit this, for the Patagonian
beds are found far to the south (between 45 and 50° S.
lat.), while the Entrerios beds are in 30-35° S. lat. It is
true, there are localities for Entrerios beds farther to the
south (as far as about 43° S. lat.), but of the character-
istic tropical types, which are named by von Ihering (on
p. 361) not a single one is found at these southern locali-
ties (see table on pp. 357 and 358). Thus it is very prob-
able that, while at the time and the locality of the depo-
sition of the Patagonian beds an extratropical climate
prevailed, a tropical climate may have existed at the
same time farther north (north of say about 40° S. lat.).
However, we do not know the corresponding deposits of
these parts, and we only know that there are tropical im-
migrants in later deposits in about 30-35° S. lat., but
this does not prove that there were no such in the north-
ern parts of Argentina at the time of the deposition of
the Patagonian beds. In fact, the presence of certain
tropical types in the Navidad beds of Chile (p. 514).
which very much resemble the Patagonian beds in gen-
eral character, but are situated a good deal farther
north, suggests strongly, that the Navidad beds are the
tropical ‘‘facies’’ of the Patagonian beds. I do not think
No. 520] TERTIARY ARCHHELENIS 241
that a separation of the Patagonian and Chilean sea by
land is to be assumed for the explanation of the absence
of these tropical types in the Patagonian beds, as von
Ihering is inclined to do (p. 495). Of course, the Pata-
gonian beds were deposited on the east side, those of
Navidad on the west side, of the old peninsula extending
northward, and now represented by the Chilean Coast
Cordilleras, but this peninsula had an end somewhere to
the north, and around this point a communication of the
' two seas was possible, till the elevation of the Cordil-
leras de los Andes took place, and connected the old
Chilean land with the land lying to the east of it.
Further, if there was no connection of Africa and
Brazil any more in Tertiary times, the migration of the
Indo-European forms to Patagonia by the route indi-
cated above (East Africa, and south coast of Archhel-
enis) was impossible. Yet there is another way open.
As von Ihering points out (p. 81), this Indo-European
fauna reached eastward to Australia and the Pacific Is-
lands, and thus it very likely does not originally belong
to the fauna of the old Tethys (Mediterranean, North
Atlantic, West Indian seas), but consists of old Pacific
elements which extended, in the Tertiary, eastwards into
the Mediterranean part of the Tethys (Europe). The
very absence of these types in the West Indies and in
North America supports this view. And further, since
the Antarctic fauna, to which the Patagonian fauna
shows the closest affinities, is nothing but an offshoot of
the old Pacific fauna, the relations of the Patagonian to
the Indo-European forms find thus their explanation,
and the way, by which these faunas are connected, ap-
parently goes over Australia and Antarctica.
Finally, for the non-existence of Archhelenis in the
Eocene very recently a new line of evidence has been
introduced. Stromer? points out that recently quite a
number of marine Eocene deposits have been discovered
2 Stromer, E., ‘‘ Ueber Alttertiaer in Westafrika und die Suedatlantis,’’
Jahrb. kgl. Preuss. Geol. Landesanst., 30, 1909, p. 511 ff.
242 THE AMERICAN NATURALIST [Vou. XLIV
in West Africa, namely, in the region south of Sene-
gambia; on the middle Niger River; in the southern
central Sahara and in northern Nigeria; in Togo and
Cameron (Gulf of Guinea) ; and even as far south as the
Gabun, Angola and Mossamedes. Although these de-
posits are rather scattered, their Mediterranean character
has been recognized, so that it appears as very probable
that they belong to a continuous sea, which extended
south from western Europe along the west African coast.
That is was actually continuous is demonstrated, accord- +
ing to Stromer, by the distribution of the Nummulites
in these beds, which are found only in the north, and
indicate a cold northward current along the west African
coast: such a current could develop only under a similar
distribution of land as at present, namely, if the
west African coast extended uninterruptedly from south
to north, as it now does. This, of course, would show
that the Atlantic at that time existed approximately in
its present form, its northern (Tethys) and southern
(Nereis) parts being connected, and that the separating
land bridge, Archhelenis, had disappeared.
All the above considerations lead us only to one con-
clusion : that in the beginning of the Tertiary Archhelenis
had ceased to exist, and that there was no connection any
more between South America and Africa. Indeed, the
facts introduced by von Ihering in support of his assump-
tion of the existence of this land-bridge in the Eocene,
prove to be, under renewed critical investigation, the
strongest evidence for the contrary, and it has been shown
above that also some other facts, which apparently con-
tribute to the support of von Ihering’s view, may be
easily understood under the assumption that Archhelenis
had been destroyed at the beginning of the Tertiary
time.
SHORTER ARTICLES AND DISCUSSION
THE PROBABLE ORIGIN OF THE CRINOIDAL
NERVOUS SYSTEM
ALTHOUGH at first sight the nervous system of a crinoid ap-
pears to be so radically different from that of an invertebrate of
the more usual bilateral type that no satisfactory comparison is
possible between them, I believe that there is no difficulty at all
in deriving it from the latter.
The nervous system of a crustacean, worm or insect consists
typically of a supracsophageal ganglion united by a pair of
cireumcesophageal ganglionic connectives to a more or less
marked subcesophageal ganglion, from which there runs back
along the ventral side of the animal a long nerve cord, or pair of
nerve cords, marked at intervals with ganglia. The anterior end
of the digestive tube passes between the two chief ganglionic
masses, as the names of all these structures indicate.
The ancestral crinoid was bilateral, and therefore possessed a
nervous system constructed according to this plan. With the
progressive decrease in directive locomotion the ventral nerve
cord was correspondingly shortened, concurrently with the as-
sumption by the animal of a more compact form, just as the
nerve cord has been shortened in Cancer as compared with Pal-
inurus, in Dynamine as compared with Apseudes, in Cimes as
compared with Diapheromera, or, better, in the crustaceans as a
class as compared with the annelids as a class. In the erinoids
the shortening progressed still further; locomotion, other than
casual or accidental, ceased; the anterior end of the intestinal
canal became deflected upward and pressed upon the anterior
part of the supracesophageal ganglion which gave way before it
and became deeply crescentic; at the same time the ventral
nervous cord was retracted into a short protuberance from the
subcesophageal ganglion. Finally the horns of the crescent
formed from the supracesophageal ganglion met in front of the
throat so that what was originally a ganglion mass became a
nerve ring, the two connectives became broken up into numerous
eonnecting fibers, and the whole ventral nerve cord with its
243
244 THE AMERICAN NATURALIST [ Vou. XLIV
ganglia became retracted into the subcesophageal ganglion, now
become the dorsal nerve mass.
Thus we may very easily derive the radiating nervous system
of the crinoid from the bilateral nervous system of the
arthropod, the circumoral nerve ring of the crinoid being
derived from the supracesophageal ganglion of the arthropod,
and the dorsal nervous system from the subcesophageal ganglion.
In this connection it is significant that the cireumoral nerve ring
innervates the same structures and possesses the same functions
as the supracesophageal ganglion, while the dorsal nervous sys-
tem is identical with the subceesophageal ganglion, plus the ven-
tral nerve cord, in the nature of its duties.
The assumption of the pentaradiate form by the crinoids has
produced a complex condition of orientation; for the so-called
‘‘ventral’’ surface of the crinoid, in terms of arthropod or anne-
lidan orientation, is equal to the anterior end, plus the posterior
end, and plus such part of the dorsal surface as is not shoved to
one side by the approximation of the two extremities of the in-
testinal canal; while the ‘‘dorsal’’ surface of the crinoid is the
equivalent of the entire ventral surface of the arthropod, plus
more or less, possibly nearly all, of the dorsal surface.
Austin H. CLARK.
NOTES AND LITERATURE
RECENT LITERATURE TOUCHING THE QUESTION OF
SEX-DETERMINATION
In 1889 Geddes and Thomson in their book on the ‘‘ Evolution of
Sex’’ stated that ‘‘ Nutrition is one of the most important factors
in determining sex’’ (p. 47), and developed the theory that
‘** Anabolic conditions favor the preponderance of females, kata-
bolic conditions tend to produce males” (p. 47). In the revised
edition of 1901 practically the same idea is stated thus: ‘‘The
female is the outcome and expression of relatively preponderant
anabolism, and the male of relatively preponderant katabolism’’
(p. 140). The following year (1902) Beard! expressed the con-
clusion, based upon considerable evidence, that: ‘‘Any inter-
ference with, or alteration of, the determination of sex is abso-
lutely beyond human power. To hope ever to influence or
modify its manifestations would be not less futile and vain than
to imagine it possible for man to breathe the breath of life into
inanimate matter’’ (p. 763).
The two fundamental ideas here expressed—namely, that the
nature of the environment (chiefly the amount of nutrition) may
determine the sex of the developing germ, i. e., that sex is quanti-
tatively determined ; and that sex is predetermined in the germ,
i. e., qualitatively (independently of external conditions if only
they be favorable to development) have until recently sharply
divided investigators on the problems of sex. Both positions
seemed about equally well supported by numerous facts both
experimental and cytological for animals, and experimental for
plants. In only a few instances has opinion been divided over
the same form; in the majority of cases the results appeared
convincingly in favor of one or the other view.
The more recent tendency seems to be to interpret sex-deter-
mination (at least proximately) as the result of a quantitative
relation between karyoplasm and cytoplasm in the fertilized
ovum, or more strictly, between chromatin and cytoplasm. This
position rests upon the observation chiefly that in those insects
where heterochromosomes have been described the eggs which
develop into females contain the greater amount of chromatin
material (exceptions—Metapodius, Wilson; and possibly Acholla,
1 Beard, John, ‘‘The Determination of Sex in Animal Development,’’
Jena, 1902.
245
246 THE AMERICAN NATURALIST [Vou. XLIV
Payne), and has been suggested as probable more particularly by
Morgan and by Wilson. The former,” however, regards the
quantitative interpretation of sex-determination as only the
‘first rough approximation’’ (p. 348) to the solution; and the
latter? inclines to the belief that ‘‘if the idiochromosomes be sex-
determinants their difference is probably a qualitative one” (p.
189), though this may possibly be a difference merely of degree
of special activity.
Boveri’s‘ generalization that the cytoplasm and nucleoplasm
of cells bear to each other a constant ratio, and that ‘‘a ferti-
lized egg that contains more chromatin is a potentially larger
cell than one with less chromatin’’ (pp. 9-10) may help to recon-
cile the conflicting theories. If the amount of chromatin may
be rightly taken as an index of the state of nutrition or poten-
tial anabolic capacity, the apparently contradictory facts that
nutrition (environment) in one case and internal factors (per-
haps simply more or possibly more active chromatin) in the
other case determine sex, can be harmonized. If chromatin and
chromatic substances (nucleo-proteids) may be regarded as food
material or active agents in constructive metabolism, the better
nourished gametes (or such as contain more chromatin) appear
destined to produce the female sex, the less well nourished the
male sex.
Several recent investigations again affirm the opposing views,
well supported with experimental or cytological facts, though a
reconciliation is suggested from both sides on the basis of a
quantitative relationship signifying in one direction high metab-
olism (anabolism) and in the other low metabolism (‘‘relatively
preponderant katabolism’’).
The most important recent paper concerning the question of
the determination of sex is that of Russo.” This author takes
issue with the prevailing hypothesis which views the chromo-
somes as the vehicles of the determinants of hereditary charac-
ters, and objects more especially to a Mendelian interpretation of
2 Morgan, T. H., ‘‘A Biological and Cytological Study of Sex Deter-
mination in Phylloxerans and Aphids,’’ Journ. Exp. Zoöl., Vol. 7, no.
2, 1909.
3 Wilson, E. B., ‘‘Studies on Chromosomes, V.’’ Journ. Exp. Zodl.,
Vol. 6, no. 2, 1909.
+ Boren, Th., ‘*Ueber Beziehungen des Chromatins zur Geschlechts-
GP, 7 Bite. Phys. med. Gesell. Wurtzburg., Jahrgang 1908-1909.
5 Russo, A., ‘*Studien ueber die Bestimmung des weiblichen Gesch-
lechtes,’’ Jena, 1909, pp. 1-105.
No. 520] NOTES AND LITERATURE 247
sex-phenomena. The fact that in the gametes, particularly the
eggs, besides certain phosphorus-containing proteins, lecithin is
abundantly present, suggested a series of experiments to deter-
mine whether the lecithin content of eggs could be artificially
increased and whether such accession could produce a significant
physiologic modification in the germ-cells.
Russo finds that normally in rabbits and various other mam-
mals the lecithin content of eggs of the same ovary varies
greatly; some containing much, others little. This variable cell
condition indicates a shifting chemical state, expresed morpho-
logically in the form of ‘‘chromidial-bodies’’ (mitochondria,
chondriomites, pseudochromosomes, chromidial net, ete.). These
structures Russo has succeeded in producing by artificial means
(i. e., injection of lecithin), and he regards them as having
small influence on developmental phenomena.’’ He does not
deny that the nuclear chromatin plays an important rôle in
development, but he refuses to regard it as alone the material
basis of heredity. The nuclei may assist in the process of hered-
ity, but the results of his investigations on rabbits indicate that
sex and other ‘‘unit characters” (e. g., pigmentation) are a func-
tion of the degree of cell metabolism.
Russo believes that ‘‘contrary to the chromosome theory, the
characters of Mendelian hybrids in the first or dominant genera-
tion, especially as concerns the pigmentation and color of the
hybrid, do not bear any absolute relation to the chromosomes,
but that they depend in greatest part upon a specific metabo-
lism or chemical condition residing in the egg cytoplasm; that,
further, the sex of the offspring depends upon a special metabo-
lism (Stoffwechsel) of the germ-cells, and that by artificial
modification of the chemical or metabolic state (Metabolismus)
of these elements the Mendelian law (i. e., of dominance) can be
' modified in that one may fix this or that most recent variety,
as it is also possible at will to determine the sex’’ (p.
Lecithin was administered subcutaneously, intraperitoneally
and per os. The ovaries of lecithin-fed rabbits attained a size
three times as great as that of ordinary individuals and con-
tained much larger Graafian follicles. Under such treatment
the germ cells became markedly anabolic. Russo notes that in
normal ovaries some ova contain much deutoplasmie material
in the zona pellucida and the vitellus, and others little or none.
The artificially highly nourished eggs produce females; and the
lecithin-fed individuals give rise preponderatingly or even ex-
248 THE AMERICAN NATURALIST [Vou XLIV
clusively to female offspring. There are thus in rabbits two
kinds of eggs corresponding, respectively, to each sex: (1) well
nourished, highly anabolic, or female; (2) poorly nourished,
slightly anabolic (or katabolic) or male.
The sperm, containing chemical substances similar to the eggs,
are regarded as merely giving aid in the development of a process
already begun in the egg leading towards the determination of a
particular sex. That the sperm has a complementary and not an
antagonistic rôle in sex-production seems established by the fact
that the percentage of female offspring is higher when both male
and female have been subjected to the lecithin treatment before
union.
For the experiments Russo employed selected and ordinary
varieties of rabbits. His chief aim was to ‘‘fix’’ a particular
‘unit character” of the female in the offspring (mostly female)
of the first hybrid generation. The character selected was the
color of the hair. Females of recent races characterized for hair
color, 7. e., white (albino, Himalaya, Angora, ete.), were crossed
with ae of various phyiogenatiealiy older races (e. g.,
‘*Grigia’’—gray, and ‘‘Nero’’—black). The best results were
obtained from crosses between Himalaya females and ‘‘Nero’’
males. On crossing females of either albino or Himalaya races
with males of ‘‘Grigia’’ and ‘‘Nero”’ stocks the offspring of the
first generation always had the color of the male, i. e., gray or
black, respectively, showing that these crosses ordinarily conform
to the Mendelian law of dominance. Moreover, Russo notes that
in nature the number of male offspring always exceeds that of
the female, the percentage of the former being variously given
as from 52 to 58 per cent.
When the same females were subjected to the lecithin treat-
ment before conception, the offspring of crosses similar to the
above were in the first generation preponderatingly of the type
of the newer or female race. There frequently appeared atavis-
tie exceptions, interpreted as due to a late ripening of the eggs
concerned which consequently remained unaffected by the
lecithin
The most clear-cut result was obtained from the following
experiment: A preliminary experiment, several times repeated,
having shown that the ordinary cross conformed to the law of
dominance, a young well-nourished ‘‘Polacea’’ (white) lecithin-
treated female was crossed with a ‘‘Nero’’ male (black). The
resulting progeny included 6 females (5 white) and 2 males (1
No. 520] NOTES AND LITERATURE 249
white), showing clearly that the female subjected to lecithin
treatment yields a preponderance of females (with the maternal
somatic character of hair color).
Occasionally the cross between a lecithin-fed Himalaya female
and a normal ‘‘Nero’’ male resulted in several modified Hima-
laya offspring (e. g., black legs or dusky coat, ete.) among the
preponderating Himalaya hybrids. This condition is readily
explained by assuming that in such crosses ‘‘the modification of
the vitellus had not reached the necessary stage to impress upon
the embryo the character of the maternal metabolism and with
it the characteristic female features’’ (p. 16).
The cause of the concomitance of sex and particular somatic
characters is believed by Russo ‘‘to depend upon a suitable modi-
fication of the germ-cell, related in some way to the age, the
physiologic state and other conditions of the particular indi-
vidual’’ (p. 98).
The evidence here appears unequivocal that external condi-
tions (e. g., nutrition) can determine the kind of sex and
entirely vitiate the Mendelian scheme of ordinary crosses. Fe-
male sex and the maternal character of coat color moreover are
shown to be associated with a more highly nourished egg, the
artificially modified metabolism expressing itself in an abund-
ance of deutoplasmie and chromatic substances (chromidial-net)
in the zona pellucida and vitellus. The main stages in the chain
of causes culminating in female sex seems to be, (a) high nutri-
tion (lecithin), (b) increased size (preponderant anabolism),
(c) storage of chromatin, (d) femaleness.*®
A brief paper by Miss Boring’ gives the results of a careful
study of fertilized eggs of Ascaris with special reference to the
€ The relation of nutrition to sex-determination as demonstrated by Russo
for the rabbit gy 86 a possible physiologic basis for the theory of sex-
causation in man (based solely on clinical facts) as recently advocated by
Dawson to the effect gone females develop from eggs from the left ovary
and males from eggs from the right ovary;—namely, that the permanent
passive congestion in the left ovary, due to the entrance of the left ovarian
vein at a right angle into the renal vein (whereas the right ovarian vein
empties obliquely directly in the inferior vena cava) may eh a con-
dition of relatively better nutrition. Cognizance must be taken of the
fact, however, that the right ovary is frequently slightly larger geome the
left, a point which apparently contradicts the verity of this interpretation;
but cytological investigation may reveal a better nourished condition of
all of the ova of the left ovary, expressed in the presence of chromidal
nets, etc.
7 Boring, Alice M., ‘‘A Small Chromosome in Ascaris megalocephala,’’
Arch. f: Zellforschung., Ba. 4, H. 1, 1909.
250 THE AMERICAN NATURALIST [ Vou. XLIV
small odd chromosome previously noted by Herla and later also
by Boveri. This peculiar chromosome is said to be very rare in
the variety bivalens. Its representative was never discernible
in the odgonia and only very rarely in the spermatogonia. From
observations of bastard eggs the conclusion is drawn ‘‘that the
small chromosome surely comes from the spermatozodn in some
eases, and possibly from the egg in others’’ (p. 125—one instance
noted). The possibility is suggested that the small chromosome
is a sex-determining heterochromosome; but Miss Boring has
no doubt also that it is sometimes due to fragmentation.
Boveri! inclines to regard this fifth (‘‘X’’)—chromosome of
Ascaris megalocephala bivalens (present in approximately half
the eggs) as comparable to the accessory chromosome of Pyrrho-
coris. He considers it more probable that its occasional appar-
ent absence (common condition in wnivalens) is the result of
fusion with one of the other chromosomes, than that its presence
is the result of fragmentation. He concludes that the ‘‘x-chro-
mosome’’ appears to be an independent structure specific for the
male sex—as was originally believed by MeClung for insects.
In analogy with conditions in insects (e. g., Protenor), Boveri
assumes a dimorphism of spermatozoa, due to the presence of
the x-element in half of the sperm and its absence in the other
half. But the unfertilized eggs are supposed to have no homolo-
gous elements (there being no evidence of such structures) ;
hence, contrary to his recent generalization that the female fer-
tilized egg contained the greater amount of chromatin, the male
sex here seems conditioned by, or concomitant with, a relative
preponderance of chromatin. This contradiction is elucidated
by facts discovered by Boveri and Gulick (op. cit., p. 136) in
a study of the spermatogenesis and maturation of Heterakis, a
nematode of the pheasant. The spermatogonial cells have 9 chro-
mosomes; the maturation spindles of the eggs 5. Two types of
spermatids are produced, one with 4 the other with 5 chromo-
somes; and one kind of egg with 5 chromosomes. The condition
is identical with that described by Wilson for the hemipter,
Protenor.
These facts established for Heterakis, give a clue to the more
probable state of affairs in Ascaris. Boveri reconciles the dis-
erepancies by assuming a close union in the odcytes of the homo-
logues of the accessory chromosome with the other chromosomes
thus Ere their presence. In reality, then, Ascaris mega-
, Th., ‘‘Ueber ‘Geschlechtschromosomen’ bei Nematoden,’’
phe my P E Bd. 4, B: 1, 1909.
No. 520] NOTES AND LITERATURE 251
locephala bivalens would have six (6) chromosomes in the female
and five (5) in the male (apparently four (4) in each since
the heterochromosomes commonly couple with the ordinary
chromosomes).
The attempt to rationalize the assumption of such a union
involves the hypothesis of chromosome individuality in extreme
form, viz: ‘‘ We can not doubt that also in the apparently homo-
geneous nucleus of the spermium each chromosome preserves
its individuality ; but all are most closely pressed together’’ (p.
139). The greater effort here demanded (as compared with the
egg pronucleus) to separate the chromosomes in this more com-
pressed condition affects also the odd chromosome and frequently
disjoins it from its ‘‘companion.”’
Thus two more forms (from the group of the Nematodes) are
shown to conform to Wilson’s scheme of sex-determination.
And though Boveri is forced to retract (p. 137) his former state-
ment regarding a preponderance of chromatin in the female
sea-urchin as judged from Baltzer’s plates the evidence accumu-
lates that the female sex is somehow associated with a greater
amount of chromatin.®
In an extensive paper of 110 pages on sex-determination in
Polyps, Nussbaum? describes in detail a large series of experi-
ments extending from 1891 to 1897 on Hydra grisea. His dis-
cussion of results involves comparisons with the works princi-
pally of Krapfenbauer (H. fusca), Frischholz (H. fusca and H.
grisea), Whitney (H. viridis) and Annandale (H. orientalis).
The aquaria were all arranged under similar conditions of
light and heat; only the nutritive conditions were caused to vary
by changes in the amount of food supply and by induced periods
of budding. The temperature is said to have an effect on sex
only indirectly through influence on the nutrition. In contra-
distinction to the four above-named investigators, Nussbaum
maintains that the nutrition and not the temperature is the chief
factor which determines change from the asexual or budding
condition to the sexual (dicecious and hermaphrodite) ; though
he agrees with the latter two that for each species there is a
definite temperature-optimum.
9 The case of Acholla multispinoa described by Payne (Biol. Bull., Vol.
16, nos. 3 and 4, 1909) may perhaps prove a real exception, though it may
be harmonized, as Payne suggests, by assuming a greater combined activity
for the several smaller ‘‘ differential chromosomes,’’ than for the single
absolutely larger male member.
10 Nussbaum, M., ‘‘Ueber Geschleschtsbildung bei Polypen,’’ Arch.
(Pflüger) f. Physiologie, Dec. 30, 1909, Bd. 130.
252 THE AMERICAN NATURALIST [Vou. XLIV
With good feeding budding gives place to a sexual phase. On
the basis of daily observations of many cultures for a number of
years Nussbaum concludes that a more favorable nutritive con-
dition produces the female polyp. ‘‘The mass of food governs
budding and the production of sexual organs’’—and the best
nutrition produces females. The same polyp may enter upon
repeated sexual phases each separated by a period of budding;
but, while he seems to deem it possible, he has not yet succeeded
in changing the sex of the same individual polyp directly into
the opposite sex.
Here again the same general conclusion appears that sex is
consequent upon the degree of nutrition and that the best
nourished polyp produces eggs, i. e., high nutrition conditions
the female sex.
Nussbaum suggests an interesting new interpretation of her-
maphroditism (gynandromorphism) among insects where a
dimorphism of spermatozoa prevails, 7. e., where heterochromo-
somes are found. He believes it quite possible that occasionally
the reducing division may be omitted in spermatogenesis and
that the unmatured spermatocytes may develop directly into
functional sperm. Shortly before, or at the time of, the first
segmentation of an egg fertilized by such a spermatozoon, the
male pronucleus is supposed to undergo its belated reduction
division, one half (with the even number of chromosomes) pass-
ing to one daughter cell with one half of the developing egg
pronucleus, and the other half (with the odd number of chromo-
somes) with the other similar half to the other cell. Thus would
result a two-cell stage, one blastomere (female) containing one
more chromosome than the other blastomere (male). If then, as
has been experimentally demonstrated in several forms, each
blastomere gives rise to one half of the resulting individual the
symmetry of the insect hermaphrodite would be explained. Here
again sex is thought of as determined by a quantitative relation
of chromatin.
The results of the newer investigations on sex-determination
seem, at least temporarily, to have brought us back to the posi-
tion of Geddes and Thomson, namely, that femaleness is caus-
ally related to a dominating cell-anabolism and maleness to a
relatively preponderant cell-katabolism. This conclusion would
seem to be the base from which future investigations will start
in the attempt to further elucidate the fundamental mechanism
of sex-differentiation. - H. E. JORDAN.
UNIVERSITY OF VIRGINIA.
No. 520] NOTES AND LITERATURE 253
RECENT INVESTIGATIONS ON THE COMPARATIVE
ANATOMY OF CONIFERS
UNTIL quite recently there has been an increasing tendency to
regard the two important coniferous tribes which are, at the
present epoch, respectively characteristic of the northern and
southern hemispheres, viz., the Abietineer and Araucarinex, as
of different origin and not ‘Spare allied with one another. This
view of their derivation is, for example, represented by Professor
Seward in his monograph on the Araucarinex* and by Professor
Penhallow in his ‘‘Manual of North American Gymnosperms. ”’?
A similar opinion has even quite recently been expressed by Mr.
Thomson.? While the inferences of those whose conclusions are
based almost entirely on a consideration of the structure of ex-
isting representatives of the Coniferales and of their surmised
ancestors from the Paleozoic, have had the marked separatist
trend indicated above, of late quite another tendency has made
itself felt as a consequence of the structural investigation of the
Mesozoic conifers and a comparison of these with existing tribes.
An important contribution on the structure of the Jurassic
woods of King Karls Landt contains an account of a ligneous
species, which the author names Cedroxylon transiens. This
species is remarkable for the fact that it at the same time mani-
fests the ray structure of the Abietinee and in many instances
the characteristic alternating radial pitting of the tracheids,
which is a feature of the wood in existing Araucarinee. On
account of the latter feature Gothan, while referring the wood
to the abietineous genus Cedroxylon Kraus, applies the specific
appellation transiens, to indicate that in his opinion the wood in
question marks a transition from the Abietinee to the Aura-
carinee. Of the general soundness of this view there can be no
question. Nearly contemporaneously Jeffrey published an ac-
count of another Mesozoic wood presenting the same structural
peculiarities as Cedrorylon transiens, together with the added.
abietineous feature of the possession of short or spur shoots, re-
1¢¢ The Araucariner, Recent and Extinct,’’ Phil. Trans. Roy. Soc.
London, 1906.
2 Ginn & Co., Boston, 1907.
at The Mignaporophyll of Saxgothea and Microcachrys,’’ Bot. Gazette,
47, May, 1909.
t Gothan, W., ‘‘ Die Fossilen Hoelzer von Koenig Karls Land,’’ Kung.
Svensk. Vetenskap. Handlingar, 42, No. 10
254 THE AMERICAN NATURALIST [ Vou. XLIV
sembling in their anatomical relations those of the living Pinus.”
The latter author, however, differs diametrically in his point of
view from Gothan, since he regards Araucariopitys, in spite of
its numerous abietineous features, as none the less an araucarian
conifer and as indicating the derivation of the Araucarine from
an abietineous ancestry rather than the reverse, as is assumed by
than.
Quite recently Hollick and Jeffrey have published an exten-
sive memoir on the structural remains of the Cretaceous conifers
of Staten Island,’ in which they describe for the first time the
anatomical organization of the branches, leaves and cones of a
number of well-known Mesozoic conifers hitherto recognized
from impressions alone. They reach the conclusion that the ex-
ternal appearance of Mesozoic conifers is in general very mis-
leading as to their real affinities. The supposed Sequoias of the
Cretaceous, for example, turn out from the internal examina-
tion of all their organs not to belong to the modern genus at all
but to be closely related to those araucarian conifers, which are at
present limited in their range to the southern hemisphere. The
same result is reached in regard to a number of other genera,
which have been connected with the living Sequoiinex, Cupres-
sineæ and even the Podocarpineæ. These authors further con-
elude that the general structure of Cretaceous conifers of arau-
carineous affinities is good evidence for the derivation of the
Araucarinee from a stock resembling the Abietineæ and not for
the reverse mode of origin, which is universally accepted by
those whose conclusions are mainly based on a structural and
habital comparison of living conifers with the gymnosperms of
the Paleozoic, since the transitional forms are all clearly on the
araucarian side.
Sinnott has recently described an araucarian wood, which in
the former state of our knowledge would have inevitably been
referred to the abietineous genus Cedrorylon Kraus.” From the
study of the ray structure of this fossil wood and from the ex-
amination of the tracheids in connection with new criteria
recently formulated, this author comes to the conclusion that his
wood represents a type of the Araucarinex, transitional towards
s Jeffrey, E. C., ‘* Araucariopitys, A New Genus of Araucarians,’’
Bot. Gazette, Dee., 1907.
<t Cretaceous Coniferous Remains from Kreiseherville, New York,’’
Mem. New York Bot. Garden, III, May, 1909.
1 Sinnott, E. W., ‘‘ Paracedroxylon, A New Type of Araucarian Wood,’’
K Vol. ITI, Book 1909.
No. 520] NOTES AND LITERATURE 255
the ancestral Abietinee, which he names Paracedroxylon, on
account of its general resemblance to the abietineous wood genus
Cedroxylon Kraus.
In an important though brief article on the occurrence of the
“bars of Sanio’’ in recent and extinct coniferous woods, Miss
Gerry® comes to the interesting conclusion that the presence of
this structural feature, consisting of transverse bands of cellulose
interposed between the radial pits of the tracheids of the wood,
is characteristic of all conifers, except the Araucarinew. Her
results are of special significance in connection with the conclu-
sions reached by Jeffrey and Hollick, cited above, in regard to
the true affinities of the supposed Sequoias, Thuyas, ete., of the
Mesozoic. On the basis of the absence of the bars of Sanio in
well-preserved woods of supposed Cretaceous Sequoias, ete., she
arrives at the result that these are in reality of araucarian affini-
ties, as was inferred by the authors just mentioned, as the conse-
quence of the combined structural study of the branches, leaves
and cone-seales of the conifers in question.
The general result of all the investigations cited in the fore-
going paragraphs is to show that there existed during the Meso-
zoie conifers, which were clearly transitional between the abieti-
neous and araucarineous types of the present day. The pre-
dominance of the testimony moreover in favor of the Abietiner
rather than the Araucarinee having been the older coniferous
tribe is apparent. Recently Jeffrey has brought forward very
definite positive evidence in favor of this view, based on the
structure of Mesozoic pines.? Known structurally heretofore
only as to their wood, the pines of the Cretaceous, which are not
without closely allied relatives in the earlier Mesozoic, are here
described in relations to the very important features of leaf
structure. Among the abietineous remains the most significant
because the most archaic genus is Prepinus Jeffrey, which has a
detailed resemblance in foliar organization to certain Cordaitales
of the Paleozoic, as well as the centripetally formed primary
wood which is the common possession of the Pteridophyta and
the lower gymnosperms. The author was moreover able to trace |
a complete seriation among various representatives of Cretaceous
pines, in leaf organization, from the type presented by Prepinus,
to that which characterizes contemporary species of Pinus. It thus
appears that the abietineous line is definitely connected with the
8 Gerry, Eloise, Annals of Botany, Vol. 24, No. 93, Jan., 1910.
® Jeffrey, E. C., ‘f On the Structure of the Leaf in Cretaceous ona
Annals of Botany, Vol. 22, No. 86, April, 1908.
256 THE AMERICAN NATURALIST [Vou. XLIV
Paleozoic gymnosperms, particularly with the Cordaitales, and
in this respect has the strongest claim to be considered as the
oldest representative of the coniferous stock.
In a recently published article, Jeffrey considers certain
abietineous features, such as resin canals of the secondary wood,
or the occurrence of marginal ray tracheids, which are found as
abnormalities in certain species belonging to the sequoiineous
and eupressineous tribes of conifers.1° He reaches the conclu-
sion that these abnormal abietineous features of the tribes in
question are not indications of the derivation of the Abietinez
from them, as has been inferred by Penhallow and others, since
recent structural paleobotanical investigations show that the
Abietinee are immeasurably older geologically than the se-
quoiineous or cupressineous tribes. The conclusion is arrived
at that the resin canals or ray tracheids, which sporadically occur
in the woods of Sequoia, Thuya, Sciadopitys, Cunninghamia, ete.,
indicate that the Sequoiinee and Cupressines came off from the
Abietineew in the late Mesozoic or early Tertiary, after the
latter had developed marginal ray tracheids in their wood rays.
„The general result of numerous recent investigations on the
anatomy of living and extinct conifers is to show that the two
coniferous tribes which have to-day diametrical polar distribu-
tion are both very old, reaching back as far as the Paleozoic, that
now widely separated geographically and anatomically they once
flourished side by side in the northern hemisphere and were
connected phylogenetically by a series of transitional forms.
The preponderance of evidence moreover seems to vouch for the
greater age of the Abietineew. The more modern and cosmopoli-
tan tribes, the Sequoiinee, Cupressiner, Taxineæ, and Podo-
carpineæ appear further to have been derived from abietineous
forebears at a comparatively recent epoch. Even the Podocar-
pineæ of present characteristic antarctic range, appear from Miss
Gerry’s interesting investigations, to have come from the
general abietineous stock and not from the Araucarinee, as has
been the conclusion of those who have recently investigated the
microgametic structures of the araucarians and podocarps, since
the latter possess bars of Sanio, which never occur in the Arau-
carineæ.
E. C. JEFFREY.
HARVARD UNIVERSITY.
126 Traumatic Ray-Tracheids in Cunnighamia sinensis,’’ Ann. Bot..
22, No. 88, Oct., 1908.
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ADDRESS DEPT. 64
New York
‘THE UNIVERSITY OF CHICAGO PRESS
VOL. XLIV, NO. 521 MAY, 1910
THE
AMERICAN
NATURALISI
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
(i
I. A prr of ay Recent Criticisms of the Restorations of asia: Dina-
OLLAND 259
Il. Anatomical PORSE in the biisin of Pinus. revine v. silky
Ill. Facts about the “Lobster Pearl.” Professor FRANCIS H. HERRICK . . 294
IV. Shorter Articles and PEPEE
fessor BASHFORD DEAN.
An Eighteenth Century Microscope: Pro Stomato-
lepas, a Barnacle a D in ate Throat of the ia yg rei Turtle. sonar
A. PILSBRY. The Age of Speed Sires: CASPE 302
V. Notes and Literature:
Biometrics—Recent mato Studies in Variation in Social Insects :
RAYMOND PEARL mental Zoology—The g om of Extirpation at
a 2E. N. oT E. oss
of Transplantation of the Reproductive Ci ops
Wheeler on Ants: Professor G. H. PAR
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THE
AMERICAN NATURALIST
Vor. XLIV May, 1910 No. 521
A REVIEW OF SOME RECENT CRITICISMS OF
THE RESTORATIONS OF SAUROPOD DINO-
SAURS EXISTING IN THE MUSEUMS OF THE
UNITED STATES, WITH SPECIAL REFER-
ENCE TO THAT OF DIPLODOCUS CARNEGIEI
IN THE CARNEGIE MUSEUM?
DR. W. J. HOLLAND
CARNEGIE MUSEUM
ALL paleontologists are familiar with the figure of
Brontosaurus excelsus Marsh, which was originally pub-
lished in the American Journal of Science in August,
1883, and republished with modifications in the same
periodical in 1895. This figure has since been frequently
reproduced in text-books. Paleontologists are also
familiar with the restoration of the skeleton of Diplo-
docus carnegiei Hatcher, which originally appeared in
the Memoirs of the Carnegie Museum, and is reproduced
in the second volume of the English translation of Zittel’s
‘Text-book of Paleontology,” by C. R. Eastman. Since
the time when Mr. Hatcher made this restoration the
acquisition of new material has thrown much light upon
the subject, and certain changes in the pose have been
suggested, which are reflected in the accompanying illus-
tration (Plate I), which is taken from a photograph of
1 The substance of this paper was communicated to the Annual Meeting
of the Paleontological Section of the Geological Society of America on
December 30, 1909. The paper at that time was freely illustrated by means
of the stereopticon, and a number of the pictures and diagrams then used
are herewith reproduced.
259
260 THE AMERICAN NATURALIST [ Vou. XLIV
the splendid specimen in the Carnegie Museum, replicas .
of which have been generously presented by Mr. Andrew
Carnegie to a number of the leading museums of Europe.
In The Field (London) of August 26, 1905, Mr. F. W.
Frohawk, a well-known English Hushedtor, published a
note, in which he said, among other things:
The visitor to the Reptile Gallery of the Natural History Museum can
not fail to be struck by the extraordinary pose of the gigantic skeleton.
. It would be interesting to know the reason for mounting the
specimen so high on its legs, like some huge pachyderm. As it is a
gigantic lizard, why should it not be represented in the attitude usually
assumed by such animals? ... Doubtless there is some good reason
for mounting it in such an attitude; if so, information on the subject
would be welcome.
No reply was given to this query, except incidentally
by Professor (now Sir) E. Ray Lankester, who said in a
newspaper interview that ‘‘the laterally compressed
form of the body, according to the opinion of American
students, precludes the idea that the animal could have
crawled upon its belly.’’
Shortly after the restored skeleton of Brontosaurus
excelsus, which is one of the ornaments of the American
Museum of Natural History, had been erected, Messrs.
Otto and Charles. Falkenbach, assistants in the paleonto-
logical laboratory of that museum, made a model, i
Fic. 1. Small Model of Skeleton of Brontosaurus excelsus Marsh, made by
Messrs. O. and C. Falkenbach,
which they attempted to show the Brontosaurus in a
crawling attitude. I am indebted to Dr. W. D. Matthew
for an illustration of this model, which is herewith
reproduced (Fig. 1). This model was discussed at the
meeting of the American Society of Vertebrate Paleon-
No. 521] SAUROPOD DINOSAURS 261
tologists held at the American Museum of Natural His-
tory in 1906, and by common consent was judged for
many reasons to represent the impossible.
In October, 1908, there appeared in Vol. XLII of Tue
American Naturauist an article from the pen of Dr.
Oliver P. Hay, ‘‘On the Habits and Pose of the Sauropod
Dinosaurs, especially of Diplodocus.’? Dr. Hay main-
tains that in assembling the fossil remains of these ani-
mals they should have been given a ecrocodilian attitude.
At the conclusion of his article he sums up his views
in the following words:
It seems to the writer that our museums which are engaged in mak-
ing mounts and restorations of the great sauropoda have missed an
opportunity to construct some striking presentations of these reptiles
that would be truer to nature. The body placed in a crocodile-like
attitude would be little, if any, less imposing than when erect; while
the long neck, as flexible as that of an ostrich, might be placed in a
variety of graceful positions.
This article of Dr. Hay was followed by a paper from
the pen of Dr. Gustav Tornier, who, taking his cue from
Dr. Hay, has tried to show that American paleontologists
have totally erred in their conception of the structure
of the sauropod dinosaurs, and has given his views as to
the manner in which the bones of the Diplodocus should
have been assembled. His paper is embellished by a
number of cuts. Professor Tornier’s paper was fol-
lowed in the popular scientific journal Aus der Natur
by an article from the pen of Dr. Richard Sternfeld, in
which he endorses the views of Tornier and endeavors
to hold American paleontologists up to ridicule, asserting
that they have ‘‘literally, from head to foot, miscon-
structed the Diplodocus, and probably also its near
allies.” Sternfeld enlarges upon Tornier’s views and
gives some illustrations of his own.
In the manner of a man who has made a wonderful
discovery, Tornier announces at the outset of his paper
that Diplodocus is a genuine reptile—‘‘ein echtes Rep-
til.” No student of the sauropoda has ever doubted
this. But having predicated the genuinely reptilian
262 THE AMERICAN NATURALIST [ Vou. XLIV
character of the animal, Tornier proceeds thereafter to
speak of the Diplodocus as a lacertilian—‘‘ ein Eidechse.”’
There are reptiles and reptiles. Having assured him-
self of the truly reptilian character of the animal, it was
a bold step for him immediately to transfer the creature
from the order Dinosauria, and evidently with the skele-
ton of a Varanus and a Chameleon before him, to proceed
with the help of a pencil, the powerful tool of the closet- .
naturalist, to reconstruct the skeleton upon the study of
which two generations of American paleontologists have
expended considerable time and labor, and squeeze the
animal into the form which his brilliantly illuminated
imagination suggested. The fact that the dinosauria
differ radically from existing reptiles in a multitude of
important structural points seems not to have greatly
impressed itself upon the mind of this astute critic. He
intimates that the pelvis of Diplodocus is distinctly
lacertilian. He states that the great trochanter of the
femur, which he does not designate as such, articulated
Fic. 2. Reproduction of figure given by Dr, Tornier in which he endeavors
at the left to show the hind limb of Diplodocus as mounted, and at the right
the position which he claims the limb should have.
with the ischial peduncle, and takes care to show the
point of union by means of a lettered diagram, which I
herewith reproduce (Fig. 2). He takes pains to show
that (e) the great trochanter, articulates with (c) the
No. 521] SAUROPOD DINOSAURS 263
ischial peduncle. It may be said in passing that Dr.
Tornier takes very great liberties with the outlines of the
bones. His drawing is very far from accurate. Un-
fortunately actual experiment shows, first, that it is im-
possible except by smashing the ilium or breaking the
femur to jam the head of the latter into the position
demanded for it by the learned professor; but, second,
this is the only time, it is believed, in the history of
anatomical science that any one has discovered that the
great trochanter of the femur ought to be and is by
nature intended to be articulated with the ischial pe-
duncle of the ilium, thus locking the femur into a posi-
tion utterly precluding all motion whatsoever.
The next step taken by this wonder-working com-
parative anatomist was to dislocate the knee-joint. This
he proceeds to do in a most nonchalant manner, and |
leaves the articulating end of the femur peering forth
into space (see Fig. 2, g), while the tibia and the fibula
are made to articulate with the posterior edges of the
interior and exterior condyles of the femur. Having
adopted this change, he succeeds in so lowering the hind
quarters of the Diplodocus that they must rest upon the
anterior extremity of the pubie bones, which, with the
fragile ends of the ribs, not much greater in size than
those of an ox, have thrown upon them the entire weight
of the carcass. To obviate the inconveniences of this
pose the lead pencil is again brought into requisition
and the anterior vertebre are hoisted into the air and
propped up upon the scapule, the dorsal ends of which
have been glued by a hypothetical suprascapula to the
lateral processes of the last cervical vertebre (see Fig.
3). This transference of the scapula to the Tornerian
position is done in order to give, as the author says, an
opportunity to so place the scapula that horizontal mo-
tion backward and forward may be allowed to the hu-
merus, which he takes pains to inform us is strikingly
like that of a Varanus. Upon the latter point it is quite
possible to differ from the learned critic.
The anterior portion of the trunk having been thus
264 THE AMERICAN NATURALIST [Vou XLIV
elevated, the fore legs are again dislocated at the junc-
ture of the humerus with the radius and ulna and stuffed
underneath the skeleton, while the great neck is thrown
upward in the form of a reversed letter ‘‘S,’’ the Hogar-
thian lines of which no doubt suggested themselves to
the learned reconstructionist as possessing soulful grace.
A reproduction of the skeletal monstrosity perpetrated
by Tornier is here given (Fig. 3). As a contribution
gun
iy
Fie, 3. The skeleton of Diplodocus mounted according to Tornier in the correct
position “ Richtige Stellung.” °
to the literature of caricature the success achieved is
remarkable. It reminds us somewhat of those creations
carved in wood emanating from Nuremberg, which were
the delight of our childhood, and which came to us stuffed
in boxes labeled ‘‘Noah’s Ark,” and stamped ‘‘Made
in Germany.”
I should prefer to end my communication at this point,
commending the perusal of the articles by Hay, Tornier,
and Sternfeld to the attention of those of you who are
familiar with the osteology of the sauropoda as amusing
illustrations of the manner in which it is possible for
gentlemen possessing entirely inadequate acquaintance
with a subject to ‘‘darken counsel by words without
knowledge.’’
Inasmuch, however, as Professor Tornier’s opinions
and his misleading diagrams and figures have been given
- some currency in journals intended to popularize science,
No. 521] SAUROPOD DINOSAURS — 265
it seems to the speaker that the present is a suitable
occasion in which not merely to demonstrate the utterly
absurd character of the opinions of Hay, Tornier, and
Sternfeld, but also to bring out into clearer light the
reasons why American paleontologists, and for that
matter the leading paleontologists of Europe also, have
concurred in regarding the sauropod dinosaurs as having
possessed the power to assume the position which has
hitherto been given them. At the risk, therefore, of
occupying some of your precious time I wish to take up
the subject a little more thoroughly and by the help of a
series of illustrations to make my meaning clear.
I shall begin with the structure of the pelvis in the
sauropod dinosaurs. I herewith give illustrations (Fig.
4) taken from the specimens in the Carnegie Museum of
the pelves of Brontosaurus, Diplodocus, and Haplocan-
thosaurus, the last closely allied to Cetiosaurus of Owen.
Fig. 4. 1, pelvis of Brontosaurus; 2, pelvis of Diplodocus; 3, pelvis of Haplo-
canthosaurus. From specimens in the Carnegie Museum.
Any one who has a merely rudimentary knowledge of
the pelves of the dinosauria in general knows that they
are distinctly ornithic in type, and not lacertilian, nor
erocodilian, Professor Tornier to the contrary notwith-
standing. Seeing is believing, and I also give illustra-
tions of the pelvis of a crocodile, of Varanus, of Iguana,
266 THE AMERICAN NATURALIST [Vou. XLIV
and of Uromastrix (Figs. 5-8). Compare these for a
moment with the pelves of the huge sauropod reptiles
and you see immediately that there is an enormous dif-
Fic. 5. Pelvis and hind limb
of crocodile.
Fig. 6. Pelvis of Varanus.
ference in general, and in countless details, which it is
not worth while to consume your time in describing.
Taking up now the articulation of the femur with the
via E of Iguana. I, Fic. 8 Pelvis of Uro-
Ilium; h, act a femur ; ot, ‘Bee mastris.
ond peiie anter.
acetabulum of the pelvis, we discover in the first place
that the head of the femur in the lacertilia differs re-
markably from the head of the femur in the sauropoda.
No. 521] SAUROPOD DINOSAURS 267
In the lacertilia the greater trochanter is reduced in
size and in some genera is practically obsolete; when
present and articulated it looks backward, downward,
inward. On the other hand, the second trochanter in the
recent lacertilia is enormously developed, looking down-
ward, forward, and outward (see Fig. 7). In the sauro-
poda, as in the ratite birds, the second trochanter is
obsolescent or wholly obsolete. The illustrations already
given may help to make my meaning clear. In this con-
nection it is well to study the head of the femur and the
structure of the pelvis in the struthious birds. The
analogy between these and the dinosauria has often
been pointed out. The facts to which I have called your
attention have great anatomical significance. A com-
parison of the head of the femur of the crawling reptiles
of to-day with the femur of the sauropoda shows at a
glance that in the latter the proximal end of the femur
is more like that of birds than of recent lizards. It was,
as we all know, in consequence of the recognized simi-
larity of the pelvic girdle and the head of the femur to
the corresponding structures in the ratite birds that
Owen, Marsh and all other competent students have as-
signed the femur the position which has almost uniformly
been given to it in restorations of the sauropoda, as well
as of other dinosaurs.
But let us for the sake of experiment give the femur
the same relative position which it has in the lacertilia,
in which the second trochanter plays so great a part.
To do this it is necessary to rotate the head of the femur
in such a way that the great trochanter will point down-
ward and backward. The accompanying diagrammatic
illustration shows the femur of the Diplodocus adapted
to the acetabulum after the analogy of Varanus and
Iguana (Fig. 9). Of what earthly use the hind limb of
the Diplodocus could have been to him in such a position
I leave you to determine for yourselves. It has been
suggested that kindly nature, to meet the requirements
of the case, must have channeled the surface of the earth
and provided the Diplodocus and its allies with troughs
268 THE AMERICAN NATURALIST [ Vou. XLIV
in which they kept their bodies while the feet were em-
ployed for purposes of locomotion along the banks. The
Diplodocus must have moved in a groove orarut. This
Fic. 9. The hind limbs of Diplodocus arranged after the analogy of the recent
lacertilia.
might perhaps account for his early extinction. It is
physically and mentally bad to ‘‘ get into a rut.”
Assuming that the articulation of the femur after all
was not as it is in the lacertilia, and accepting, merely
for the sake of argument, the pose of Professor Tornier,
who, though contending that the creature was a lacer-
tilian—‘‘ein Hidechse’’—nevertheless, constrained by
obvious difficulties, in his drawings does not give the
femur the characteristically lacertilian pose, I have taken
pains to place the bones of the replica of the Diplodacus
now in course of preparation for the Imperial Academy
at St. Petersburg as nearly as is possible in the position
which Professor Tornier demands that they should have.
I have accepted Tornier’s ‘‘richtige Stellung’’ for the
time being, and have collocated the bones in the position
which he demands for them, and I have the pleasure
herewith of submitting to you photographs of the bones
thus located (Figs. 10 and 11). In the first place you
will observe that it is beyond possibility, when locating
No. 521] SAUROPOD:’ DINOSAURS 269
the bones in this manner, to bring about anything like a
plausible position of the head of the femur in the ace-
tabulum. ‘The ridiculous articulation of the great tro-
chanter with the ischial peduncle demanded by Professor
Tornier, who seems to have mistaken the ischial peduncle
Fig. 10. View from behind of pelvis and femur of Diplodocus mounted
according to the Tornierian prescription. i.p, Ischial peduncle; g.t, great
trochanter; a.p, acetabular surface of pubis; a.i, acetabular face of ischium.
for an anti-trochanter, has already been alluded to. Of
course we could not accomplish such an articulation, but
we have come as near to it as the bones will allow.
Placed as nearly as is possible in the situation in which
Professor Tornier demands that the bones shall be put,
the head of the femur stands in no relation whatever to
the articulating surfaces of those portions of the pubis
and the ischium (a.p and a.i) which enter into the com-
position of the acetabulum. The lower surface of the
head of the femur is left out of all relation to these
obviously articulating surfaces at a remove from them
of at least six inches. Furthermore, in swinging the
20 THE AMERICAN NATURALIST [Vor. XLIV
bones into the acetabulum in such a way as to throw the
distal end outward, the head of the femur necessarily
enters and penetrates the opening of the acetabulum,
invading the pelvic cavity and occluding the same. But
this is not the worst. The distal end of the femur is left,
as Tornier’s figures themselves show, protruding into
space without any surface whatever with which to artic-
Fig. 11. View from side and front of femur and pelvis of Diplodocus mounted
after the Tornierian prescription.
ulate. Iam fully aware that inthe lacertilia the joint made
by the femur with the tibia and fibula, especially in young
individuals, is provided to a high degree with cartilagi-
nous connections, and the ends of the bones are covered
No. 521] SAUROPOD DINOSAURS 271
with great cartilaginous epiphyses, which in the bones
of the fossil animals we are considering have not been
petrified and preserved, but making all allowance for the
existence of these cartilaginous masses at the points in-
dicated, it is impossible to conceive that the broad ex-
panded heads of the tibia and fibula should merely come
in contact with the internal and external condyles of the
femur at two small points, in each case not larger than a
sixpence. The pose given to these bones by Dr. Tornier
represents nothing else than the complete dislocation
of the femur from the tibia and fibula.
Dr. Tornier labors long with the scapula and the
humerus. As I have already stated, he claims that the
humerus of Diplodocus is startlingly—‘‘verbliffend’’—
like that of Varanus. It is wonderful what a man can
see who has determined to see things! If you will sim-
ply take the trouble to compare the humerus of the
sauropod dinosaurs with
that of a Varanus I think
you will be able without
opening your eyes very
widely to discover a num-
ber of startling differ-
ences. In addition to fall-
ing into error as to the
startling likeness existing
between the humerus in
the sauropoda and the
lacertilia, he makes a x
multitude of grossly in- Fıc. 12. Reproduction of figures given
accurate and misleading Seapula and fore limb of Diplodocus as
statements in uttering e came it should be (right figure).
the special plea which he
makes for his theory. It would be wearisome to recall
them. One of the more noticeable misstatements is made
when he declares that the coracoid bone belongs on the
lower side of the belly—‘‘Bauchunterseite.’’ The cor-
acoid, as we all know, is a sternal element and has noth-
ing whatever to do with the “Bauch,” or belly. He
272 THE AMERICAN NATURALIST [Vou.XLIV
ignores the fact that the superior surfaces of the an-
terior ribs and the lateral processes of the anterior dorsal
vertebre unite to form a surface evidently adapted to
the end of providing a field over which the long dorsal
blade of the scapula can play. He demands for the
scapula a vertical position so as to give to the humerus
an opportunity, as he says, to move in a horizontal plane
backward and forward. He states that a vertical posi-
tion of the scapula is universal among recent reptilia,
which is not the case. It is true of the lacertilia, but
it is not true of the crocodilia. I herewith give a re-
production of a drawing copied from Blainville of a
erocodilian skeleton, and another copied from Brühl
(Fig. 13), both of which show that the scapula in the
Fig. 13. 1, the skeleton of an alligator after Blainville; 2, skeleton of croco-
dile after Briihl, showing position of scapula
crocodile has a position in the articulated skeleton similar
to that which it has in the mammalia. But lest some
one may say that the artists were mistaken, I am able
through the kindness of Dr. Geo. C. Johnston, of Pitts-
burgh, the well-known radiographer, to exhibit a num-
ber of X-ray photographs showing the scapula in posi-
tion in the common American alligator? (Fig. 14).
These photographs show the entire accuracy of the
drawings of Blainville and Brühl. And I am prepared
to further verify the drawings by an garo of an
2 At this point the lecturer threw upon the sereen a number of projec-
tions from X-ray photographs showing the limbs of the fii ss in
different attitudes. Only one of these is — in the text.
No. 521] SAUROPOD DINOSAURS 273
alligator in the flesh, in which the parts surrounding
the scapula have been dissected away, showing the
scapula in the same position which is given by Blain-
ville and Brihl. Any one who cares to verify the ac-
curacy of my statements can easily do so. The scapula
in the crocodile does not lie in the position which is given
Fie. 14. X-ray photograph of scapula and humerous of alligator in position
with foot thrown backward as far as possible. (Photographed by Dr. Geo, C
Johnston, Pittsburgh, Pa.) The scapula is not vertical.
to the scapula by Mr. Tornier in his restoration and it
certainly did not so lie in the Diplodocus, but the lateral
processes of the anterior dorsal vertebre as well as the
upper external faces of the anterior ribs united to form a
surface to which the scapula manifestly conformed itself
when in position. Any one who carefully studies the
vertebre and the proximal ends of the anterior ribs will
see that there is here provided by nature a plane adapted
to the inner surface of the scapula.
For the sake of experiment I have placed the scapula
in the position demanded for it by Mr. Tornier, and have
swung the fore limbs into place as he demands that they
shall be put (Fig. 15). The result is in every way
amusing. It leads in the first place to the entire disartic-
ulation of the humerus from the radius and ulna. But
as a secondary consequence it leads to a rather remark-
able result, which the Berlin critic did not think of. In
the position which Professor Tornier demands for the
elements of the fore limb, the foot must fall into a posi-
tion with the toes turned inwardly, while put into the
274 THE AMERICAN NATURALIST [Vou.XLIV
position which he demands for the hind limbs the toes
of the latter necessarily point outwardly. The accom-
1
2
Fic. 15. 1, rear view of scapula and fore limb of Diplodocus mounted accord-
ing to the Tornierian prescription; 2, side view of ditto.
panying diagram (Fig. 16) shows you the position which
the hind feet and the fore feet assume when placed as
Professor Tornier demands they shall be placed. Now,
attributing to the humerus backward and forward mo-
tion in a horizontal plane, you will see, as the dotted
lines in the diagram show, the result which is reached
when the humerus is thrown into a line parallel with the
line given to the femur. The toes of the manus point
inward and backward. The animal was ‘‘pigeon-toed’’
in front, while its hind feet were planted like those of a
grenadier. The animal moved forward with the hind-
feet, moved backward with its fore feet. If Tornier is
right it must necessarily have been somewhat ‘‘balled
up.”
The Berlin critic denies the possibility of a backward
and forward movement of the humerus in the scapula
in a vertical plane. As an actual fact, in the judgment of
No. 521] SAUROPOD DINOSAURS 275
competent American investigators, the articulating sur-
face of the humerus did thus move in the scapula, and the
great projection on the outer side of the proximal end of
the humerus, showing every evidence of having been pro-
vided with enormous muscular attachments, gave the ani-
mal the power to move the limb in the direction indicated,
this projection being strictly analogous in function to the
great trochanter of the humerus as it exists in the mam-
malia to-day. The statement that the downward pro-
Fic. 16. Diagram showing position of the foot of Diplodocus when mounted
and moved according to the Tornierian prescription.
jecting angle of the coracoid at its union with the scapula
to form an acetabulum for the humerus precluded back-
ward and forward motion in a perpendicular plane, as
Tornier avers, is not borne out by an examination of the
skeleton im situ. The humerus was capable of thus
moving through a very long are.
Professor Tornier utterly ignores in his discussion a
very important point, and that is, the structure of the
ribs of the Diplodocus as compared with the structure
276 THE AMERICAN NATURALIST [ Von. XLIV
of these parts in the recent reptilia. I throw upon the
sereen for purposes of easy comparison views of the ribs
as they are arranged in recent crawling reptiles and of
the ribs as they exist in the sauropoda, and more par-
ticularly in Diplodocus (Fig. 17). A glance at this dia-
eam
Fic. 17. TS dorsal rib articulated in 1, aetan 2, Varanus;
Iguana; 4, Orocodilus; 5, Diplodoc
gram must be sufficient to Show you the enormous dif-
ferences which exist, and to reveal to one who has the
least mechanical aptitude that the body, or ‘‘barrel,’’ of
the Diplodocus was constructed upon an ornithic rather
than upon a lacertilian model. The articulation of the
ribs does not lend itself to the idea that the animal pro-
gressed upon its belly.
Professor Tornier says that the long tail of the sauro-
pod dinosaurs was intended to be earried at full length
upon the ground, to stiffen and guide the movement of
the anterior portion of the body. He speaks of it as
intended for anchoring the body, describing it as ‘‘ein
No. 521] SAUROPOD DINOSAURS 277
Verankerungsmittel.’’ No doubt it did to a certain ex-
tent so function, but to regard it as having been an in-
strument for promoting, as Sternfeld indicates, a wrig-
gling motion—‘‘schlingelnde Bewegung’’—is to attribute
to the organ properties which it hardly possessed. The
tail, while capable, no doubt, when the animal assumed
a crouching position, of functioning as Tornier demands
that it shall, must nevertheless have been to a very large
degree used also as a support upon which the animal
could when necessary prop itself, as upon one of the
legs of a tripod, as undoubtedly was the case with the
carnivorous dinosaurs, to which the sauropoda are not
so very distantly related.
The theory, which has been proposed by Dr. Hay, that
it was impossible for these huge sauropods to rear up-
ward, seems to me to be one that any one who has care-
fully studied the movements of animals, and especially of
reptiles (turtles excepted), must repudiate. We know that
certain of the smaller lacertilia to-day, when in rapid mo-
tion, assume a bipedal pose. Professor Osborn in one of
his papers has given us a reproduction of the figure of
Chlamydosaurus in a running attitude, taken from an
instantaneous photograph by Saville-Kent (Fig. 18).
Fie. 18. Chlamydosaurus running. After Saville-Kent. Copied from Osborn.
Even more striking than the posture shown in this pic-
ture is the position constantly assumed by a well-known
lizard of our southwestern and western country, Crota-
phytus collaris Say. I regret that although I have had
a number of these animals in captivity at our museum
I never took the pains to have photographic snap-shots
made of them when rapidly running across the floor.
They assume when so doing a position in which the body
278 THE AMERICAN NATURALIST [ Vou. XLIV
is far more perpendicular than is the case in the picture
before you, and they carry the tail even higher. Ordi-
narily these lacertilians crawl, trailing the tail behind
them, but when alarmed they rise upon their hind feet
and throw the tail upward, moving along with great
speed. I do not advocate such a position for the tail
of Diplodocus, but, simply because it is long, to declare
therefore that it must have necessarily trailed with its
whole length upon the ground, does not appear to me
to be reasonable. Animals with tails relatively quite
as long, and even longer, are known to-day to hold them
elevated, and there was proportionately as much mus-
cular power, as shown by the muscular attachments, in
the tail of Diplodocus, as there is in the tail of a Crota-
phytus or a Chlamydosaurus. To declare as Mr. Hay
does, that these animals must have moved as crocodiles
and could not by any possibility have raised themselves
from the ground, does not appear to me to be logical. In
fact, those of us who have hunted alligators know that in
life even alligators raise themselves high upon their
legs when running, and get away like a dog at a sort
of a trot.
Tornier indulges in a lengthy criticism of the pose
given to the feet in recent reproductions of the Diplodocus
and demands that they shall be placed in a plantigrade
position. He thus takes issue with Mr. Hatcher and
with others who have carefully examined the subject.
Professor Abel, of Vienna, in criticizing Dr. Hay’s
article, has very aptly pointed out that the manner in
which the metacarpals articulate in the pes and manus
indicates a more or less digitigrade position. Those of
us who are familiar with the feet of the sauropod dino-
saurs know very well that in their structure, as indicated
by the facets of both the proximal and distal end, there
is strong evidence that they were not plantigrade in the
sense in which the feet of existing reptiles are planti-
grade. I throw upon the screen a diagram showing the
proximal ends of the metacarpal and metarsal elements
(Fig. 19). They arrange themselves in a semicircle
No. 521] SAUROPOD DINOSAURS 279
both in the hind foot and fore foot. This is less marked
in the hind foot than in the fore foot. Such an arrange-
ment of the metacarpals and metatarsals is significant,
as has been pointed out by
Hatcher and Osborn and is i?)
clearly shown by Abel.
Sternfeld brushes Abel’s 1
criticism to one side, sta-
ting that it can be easily
got rid of because. the cw
same arrangement exists in
the feet of animals which are
plantigrade. I would recom- Ses “showing a
mend Dr. Richard Sternfeld metacarpals ; 2, ot mara a i
to more carefully study the SPRAT
anatomy of plantigrades. The structure of the feet of the
sauropod dinosaurs differs immensely from that of the
feet of all recent plantigrades and all the recent reptilia.
We have evidence of a rather conclusive character as
to the fact that the sauropod dinosaurs were decidedly
digitigrade in the one existing specimen of a sauropod
footprint, which is happily preserved, a figure of which
I throw upon the screen (Fig. 20). You will see as you
examine it that the animal must have been provided, as
Professor Hatcher long ago pointed out, with a very
large foot-pad, and that its track is not at all like the
track of any of the recent lacertilia. The evidence of
this footprint is impressive and ought to go a long way
toward confirming the view, which I believe is the only
view which we can maintain, that these animals were more
or less digitigrade in the pose of their feet.
The form of the limbs, long, straight and pillar-like,
in this respect differing vastly from the limbs of the
creeping lacertilia and crocodilia, suggests that they
were intended to support a weight thrown upon them
from above. The femur of the crocodile, as you know,
is bent, and the femora of many of the recent lacertilians
likewise show a distinct curvature of the axis. The
same thing is true of the fore limbs, notably in Varanus.
280 THE AMERICAN NATURALIST [ Vou. XLIV
The axis of the proximal end of the humerus in Varanus
lies in a plane differing as much as forty-five degrees
from the plane of the axis at the distal end. ‘This is not
true in the case of the sauropod dinosaurs. ‘The limbs
were intended to bear a burden placed mainly above, and
Fig. 20. Footprint of.sauropod dinosaur. Specimen in the Carnegie Museum.
their structure seems to plainly indicate this. It is in
short impossible to articulate the limbs in such a position
as to impart to the animal a crawling attitude. We have
experimented a score of times and have tried different
poses, only to come back again to the position which we
have given to the reproduction of Diplodocus and which
is the position that has generally been accepted by osteol-
ogists as the correct position for such animals when
standing or moving forward. Our reproductions may
be, as they have been contemptuously styled by Hay,
‘‘light-legged and straight-legged,’’ but no one who
has had the matter practically in hand has yet been able
to suggest any way of escaping the conclusion that these
creatures were at all events more or less ‘‘straight-
No. 521] SAUROPOD DINOSAURS 281
legged.’’ For their ‘‘light-legged’’ qualities nature is
solely responsible, though I fail, standing before these
huge bones, to see why anybody should so describe them.
Students of the lacertilia and of the testudinata may
sneer, but it is beyond possibility to adopt the sugges-
tions which they from time to time make, that those of
us who are engaged in studing the dinosaurs shall squeeze
these creatures into the forms with which they are famil-
iar. The critics possibly do not realize that weeks and
months and years of study have been spent by those who
have been charged with the task of assembling these
remains, and that the prescriptions, which they now
furnish, have been already tried without their sugges-
tion, and have for good reasons been found wanting. It
is easy for a knight of the quill, who has never practically
attended to the matter, to find fault. The latest attack
upon those who have been making a special study of the
sauropod dinosaurs has only served in the mind of the
speaker to prove the correctness of the careful work
which has been done in the past by students on both sides
of the Atlantic. Evolution has had something to do
since the sauropod dinosaurs walked the earth, and to
say simply because the lacertilia of the present day
ereep and crawl that in Mesozoic times there were no
reptiles which walked, is to go further than the facts
seem to warrant. The pinnipedia and the cetacea live
in the waters: it does not necessarily follow that their
ancestors were aquatic in their habits and that their
limbs were like those which they possess. Because
snakes are to-day without feet or with only vestigial feet,
it does not follow -that the ancestral forms in remote
antiquity moved as they move. Because a Varanus
crawls to-day it does not necessarily follow that a sauro-
pod dinosaur crawled. There is every evidence that
they did not crawl, but that the restorations of Marsh,
Osborn, and others are substantially correct in many
important particulars. It is “ʻa far cry” from the
erocodilia, which, by the by, existed contemporaneously
282 THE AMERICAN NATURALIST [Von XLIV
with the sauropoda, and the genera Brontosaurus, Moro-
saurus, and Diplodocus.
The Tornierian hypothesis may be dismissed, I think,
as not within the range of the possible. It has, as one
of my learned paleontological friends in Europe jocosely
remarked to me, ‘‘only this feature to recommend it, that
it accounts for the speedy disappearance of the sauro-
poda, because if true, their lives must have been spent
in indescribable agony, every joint being dislocated.’’
Both Dr. Hay and Professor Tornier indulge in specu-
lation as to the food of Diplodocus. Tornier emphat-
ically repudiates the idea that the animal was herbivorous
and suggests that it was piscivorous. Sternfeld pictures
it as squatting on the banks of streams and feeding on
snails, bivalves, and amphibians. Hay approves of the
suggestion of the present speaker, that Diplodocus may
have fed upon alge. In this field we are all more or
less left to our imaginations, and one man’s guess is as
good as another’s. In view of the fact that cycads were
numerous at the time when the Diplodocus and its allies
lived and died, it may not be improper to renew the sug-
gestion that possibly these plants furnished the food of
the sauropod dinosaurs. However the terminal buds
would have been poor fodder, being woolly and harsh,
and the leaves are as stiff as wires and could not have
been masticated by such teeth as the Diplodocus pos-
sessed. On the other hand the interior of the stems of
the cycads, ‘‘sago-palms,’’ is in all recent species a
veritable mine of nutritious food, and was presumably
the same in the ancestral forms. While the compara-
tively feeble dentition of the Sauropoda would not have
been of much use in getting at these supplies of starchy
food, the heavy claw-like armature of the feet was quite
equal to the task of ripping open the thin outer bark of
the stems, and this accomplished, a single cyecad’ stem
of some of the larger species would have furnished a
good meal of soft food capable of satisfying the hunger
even of a Diplodocus. This suggestion has been freely |
discussed by the speaker with Dr. N. L. Britton of the
No. 521] SAUROPOD DINOSAURS 283
New York Botanical Garden, and seems plausible. It
is thrown out as a hint worthy of consideration. If the
terminal end of a cycad could have been torn away this
also would have given access to the mass of food in the
stem. The feeble dentition hardly seems equal to the
task of tearing away this upper growth, but if it was,
we then might have a reason for the great elongation
of the neck.
Before I conclude these remarks I desire to say that
I am not without hope that recent discoveries made by
the Carnegie Institute will tend to throw a flood of light
on the whole subject. We have found what paleontol-
ogists have been searching for for forty or fifty years,
three skeletons of sauropod dinosaurs lying articulated
where they died. They are imbedded in hard sandstone,
the work of removing which from the bones must involve
a vast expenditure of time and effort; but in one case
at least we know already that the vertebral column lies
in position, articulated from end to end. Apparently
hardly any disturbance has occurred and the bones even
to the minutest tuberosities and rugosities are as perfect
as when the animal died. The sternal ribs are present.
When we succeed in carefully working out these huge
skeletons from the surrounding matrix we shall probably
be able to clear up some of the disputed points in the
osteology of the sauropod dinosaurs.
ANATOMICAL CHARACTERS IN THE EVOLU-
TION OF PINUS:
IRVING W. BAILEY
HARVARD UNIVERSITY
Pinus is the oldest genus of the conifers and the most
important and interesting, whether considered from the
botanical, economic or aboricultural standpoint. Occur-
ring as it does in many species throughout the whole
northern hemisphere, from it are derived many of the
most valuable timbers and extractable products of com-
merce. In accordance with the general impression, that
flourishing genera are modern, since they show an obvi-
ous adaptation to existing conditions of environment, it
has been assumed that Pinus is of comparatively recent
origin and marks the last word as it were in coniferous
development. Recent investigations however of the oc-
currence of Pinus in the American Cretaceous, show that
in the lower levels of that epoch, species of pines were
apparently much more numerous than they are at the
present time. It is accordingly apparent that so an-
cient a genus as Pinus and one so richly endowed with
an abundant modern progeny supplies a particularly
favorable subject for evolutionary investigation.
It has been the practice in the past to arrange plants
systematically on the basis of external characters alone,
chiefly on the superficial features of their floral organs
and leaves. In the case of so ancient a genus as that
under consideration, this procedure has peculiar diffi-
culties connected with it, since in the tremendous period
of time during which it has been in existence, its exter-
nal characters have undergone many puzzling changes.
The internal structure of the genus however has shown
1 Contributions from the Phanerogamie Laboratories of Harvard Uni-
versity, No. 22.
284
No. 521] THE EVOLUTION OF PINUS 285
less range of variability and greater constancy in defi-
nite lines. On account of the long geological range of
- Pinus, anatomical characters, notoriously more constant
than any others found in the higher plants, have had
time to become considerably diversified. As a result of
the action of this principle, it is much more easy to dif-
ferentiate two such species as Pinus strobus Linn. and
P. palustris Mill. from one another anatomically than
distinct Cupressineous genera such as Chamecyparis
and Thuya. This arises from the fact that the Cupres-
sinew, to which the two last-named genera belong, are
of very recent origin compared with many of the species
of Pinus.
Before attacking the anatomical differences which
mark the main lines of evolution in pines, it will be well
to consider the artificiality of the groups into which they
may be divided by the use of solely superficial characters.
Such characters are the number of leaves in the fascicle,
the deciduous or nondeciduous nature of the leaf-sheath,
the texture of the cone-scale and the relative size of the
seeds. Quinate leaf fascicles formed, for example, a
very satisfactory basis for the classification of pines
before those of the southern United States and Mexico
became known to science. In Europe, Asia and northern
North America, the possession of quinate leaf fascicles
is a constant character of soft pines of the Strobus and
allied sections. In the southern region of North —
America, however, are found hard pines such as P.
Torreyana Parry, P. arizonica Englm. and P. Monte-
zume Lamb. with leaf fascicle containing five leaves.
On the other hand, a persistent leaf sheath such as is
a feature of the hard pines is absent in P. chihuahuana,
P. leiophylla and P. Lumholtzii, quite typical pines of
the group in other respects. Nor is the texture of the
cone-seale or the position of the apophysis on the umbo,
characters which are used to distinguish the larger
groups of Pines, any less exempt from disconcerting ex-
ceptions. The American nut-pines, as well as those of
286 THE AMERICAN NATURALIST [Vow.XLIV .
Asia, although belonging to the soft pine series have the
thick cone-scales and median dorsal umbo of the hard
pines. Nor is the nut-like character of the seed a con- .
stant character, for the nut-pine of Italy is a hard pine,
while those of America and Asia are soft pines. If we
seek for really dependable criteria for the classification
of pines, we have to go below the surface. The single
leaf-trace, for example, is absolutely constant throughout
the soft-pine series as is equally the case with the double
foliar bundle in the hard-pine series. Similarly, the
soft pines are characterized by a single row of resin-
canals in the first year’s growth which is duplicated or
further multiplied in the hard pines. Englemann has
further indicated the value of the number and position
of the resin canals in the leaf for diagnostic purposes.
An extremely important anatomical character for the
separation of the two great series of living pines is the
nature of the tracheid-like cells on the margins of the
wood-rays. The nature of the pitting in the tracheids
of the wood and the central cells of the wood-rays like-
wise supply valuable criteria for the establishment of
smaller subdivisions. It will be inferred from what has
been said, that anatomical characteristics in the case of
Pinus are very constant in broad lines and consequently
are for the establishment of a natural classification, in-
dicating the evolution of the genus, of the greatest
value. External characters, on the other hand, are
much subject to variability.
Two main series of pines, the hard pines and the soft
pines, may be clearly recognized, in accordance with ana-
tomical characters. For example, the groups of which
P. strobus Linn. and P. silvestris Linn. are types, are
quite distinct. The latter species is characterized with
the remaining hard pines, without exception, by the
double foliar fibrovascular bundle, two or more rows of
resin canals in the first ring of woody growth and den-
tate or reticulate marginal tracheids of the wood-rays.
The former species, together with the other soft pines,
No. 521] THE EVOLUTION OF PINUS 287
has throughout the single leaf bundle, the single row of
resin canals in the first woody ring and smooth-walled
marginal ray-tracheids.! These two great races of pines,
which may be traced from the Cretaceous to the present,
may be subdivided on the basis of other characters, in-
ternal and external. Within the subdivisions differ-
ences in floral and foliar characters are much less vari-
able than in the main lines.
The nature of the parenchyma in the wood rays and
the characters of the pits which connect them with the
tracheids are features of considerable evolutionary and
diagnostic importance in the various smaller subdivi-
sions of the genus under consideration. For example,
among the soft pines we find a group illustrated by the
nut pines and foxtail pines of the United States, and
by the nut pines of Asia (P. Gerardiana Wallich. and
P. Bungeana Zuce.), which are characterized by the pos-
session of thick-walled ray parenchyma, with very small
lateral pits having distinctly cireular borders (Fig. 1).
These pits are usually four in each ‘‘eross field” (a
cross field is the area of intersection of a ray cell and a
tracheid) and quite distinctly separated from each other.
The opening on the side of the tracheid is slit-like and
often exceeds in length the diameter of the pit. The
opening on the side of the ray cell is circular or lentic-
ular and smaller or nearly equal in diameter to the
border. In most of the nut pines and fox-tail pines
these pits are rather uniform in size and in diameter,
the same as the lateral pit in the marginal tracheids of
the rays. In P. Bungeana of China the pits are of
large size, with widely lenticular openings and more
approximated than in the other nut pines. Small lateral
pits such as those just described with distinct circular
borders are characteristic of the ray cells of most of
the conifers and are conveniently termed ‘‘piciform.’’
1 Smooth-walled except for occasional spiral markings (see Fig. 1) which
are quite distinct from the heavily sculptured reticulate and dentate mar-
ginal tracheids of the hard pines.
Paaie Il
st, Vor. XLIV
American NATURALI
OO A AL
>
No. 521] THE EVOLUTION OF PINUS 289
EXPLANATION OF PLATE
Fic. 1. Radial section of Pin Balfouriana, showing the thick-walled
character of the ray parenchyma, vey characteristic piciform pitting of the nut
pines, and a ray tacheid with spiral markings which are characteristic of this
species. x 500,
Fic. 2. Radial section of the root of Pinus tæda, showing the variation
in the aise of the pits, the distinctly bordered outlines and the increase in width
of the oriface with increase in size of the PERET x 800.
Fic. 3. Radial section of Pinus Ayacuite, showing large pits with distinct
circular borders and their fusion in places into large pits with oblong borders.
I Radial section of Pinus Lambertiana, showing the formation of
one or two medium-sized pits by the fusion of 2-4 small pits. The fusion has
progressed most rapidly on the tracheid side and the ghost-like remains of the
parenchyma partitions may still be seen. x 200
Fie. 5. Radial section of Pinus flexilis James, showing on the upper side
the process by which four medium-sized pits, diye by fusion, are fusing in
turn into one or two medium-sized pits. ie the center two medium-sized pits
are fusing into a single large pit, saig the bottom two pits, in — h the
tracheid wall has fallen away before the pas enchyma wall, ma
be s The
host-like remains of the divisions of four and five pial pits are ines iiie
0.
Fie. 6. Radial section of Pinus palustris, showing piciform pits, the in-
ae in size of these, and their fusion into irregularly shaped pits of many
form x 500.
290 THE AMERICAN NATURALIST [Vou. XLIV
In the majority of the hard pines of the United
States, we find ray pits somewhat similar to those of
the nut pines. ‘There are present one to eight small
pits in each cross-field (Fig. 2). These pits, however,
are very variable in size, number, form and structure.
In some species, and in certain regions in almost all
species, small piciform pits may be found (Fig. 6) oc-
curring with these. In most species are pits with cir-
cular borders of larger size and wide slit-like or lentic-
ular orifices (Figs. 2 and 6). In places these pits become
approximated and the borders fuse to form a single
irregular border surrounding an elongated irregular
pit. In certain species such as P. palustris Mill., P.
Murrayana A. Murray, P. teda Linn., etc., numerous pits
of large size may originate in this way. These are
often crescentic, long oval, sausage-shaped or widely
lenticular in form (Fig. 6). In hard pines we see two
distinct lines of specialization in the formation of large
pits, a tendency for the piciform pits to simply increase
in size or a tendency for pits of large dimensions to be
formed from the fusion of smaller ones. Hand in hand
with the transition from small piciform to large pits
there occurs a transition from thick to thin-walled ray
parenchyma cells. Certain Pines (e. g., P. Murrayana
A. Murray) show all gradations from thick-walled cells
such as are characteristic of nut pines to very thin-
walled cells, such as occur in the rays of P. strobus .
Linn. It is of interest to note that pit fusions take
place equally in both thick- and thin-walled ray ele-
ments. Hither the thick- or thin-walled type of cell may
predominate in the ray of the various hard pines. In
the seedling and the woody axis of the cone of such
pines, we find the ancestral piciform type of pitting well
represented, and in the cone-axis in particular the ray
parenchyma is thick walled.
In both the hard and soft pines there is a group chara-
acterized by the possession of one or two very large pits
in each cross-field (Figs. 3 and 5). In places, however,
No. 521] THE EVOLUTION OF PINUS 291
these may be represented by several small pits, and
transitions may be found showing the development of
these large pits from the smaller ones by fusion. In
Fig. 5 is seen a condition characteristic of P. strobus
Linn., P. silvestris Linn., P. Laricio Poiret., P. Thun-
bergii Parl., P. Koraiensis Sieb. et Zucc., P. resinosa
Sol., P. Cembra Linn. and other pines with large lateral
ray pits. In the upper part of Fig. 5 the stages in the
development of two large pits from four small ones may
be made out, while in the central region appears the
origin of a single large pit from two smaller ones. In
the lower part of the same figure may be seen instances
of multiple fusion, such as are particularly character-
istic of the soft pines, where the pit openings on the
side of the tracheids often fuse before those on the side
of the ray, so that the ghost-like relic of the separating
ray wall may still be observed. In Fig. 4 is seen a con-
dition, which may be considered to illustrate the forma-
tion of pits of medium size in Fig. 5. One or two rather
small pits are being formed in most cases from the
fusion of from two to four very small piciform pits.
In Fig. 3 is seen a condition characteristic of certain
soft pines (P. Avacuite Ehrenberg, P. albicaulis Englm.,
ete.) where the large-bordered pits have formed and are
fusing in places to form elongated pits with oval out-
lines. The large pitted soft and hard pines show in the
seedling a reversion to the ancestral condition of numer-
ous small pits and in their cone-axes piciform ray pits
are characteristically present. Such pines have ordi-
narily thin-walled rays cells, with the exception of such
intermediate species as P. Lambertiana Doug. and P.
Ayacuite Ehrenb.
With this review of the ray pitting in modern pines,
it will be apparent that in the nut and fox-tail pines we
have exclusively piciform pitting in the lateral walls of
the ray. This condition is of interest because it per-
petuates the type of pitting which has been invariably
found in the rays of Cretaceous pines as well as in
292 THE AMERICAN NATURALIST [Vou. XLIV
Prepinus Jeffrey, which must be regarded as a very
antique representative of the pine-like conifers. This
is particularly significant on account of the other an-
cestral features presented by the nut pines. In both
the hard and soft pines of the present epoch we find a
gradual transition from the thick-walled rays cells with
abundant piciform pitting of the ancestral type to thin-
walled cells with few large compound pits. These large
pits have been formed for the most part by the fusion
of smaller pits, although in some instances they appear
to have been derived by the simple enlargement of the
piciform type of pit. It is of interest to note that the
succiniferous pines, which gave rise to the Baltic amber
in the late Eocene or early Oligocene, already show the
transition from the piciform to the large type of pit.
Conwentz notes that there may be from one to four
pits in each cross-field and that the number decreases
with the increase in size. He further notes that in
certain regions the pits are predominantly small and in
others large, but draws no conclusions as to the origin
of the latter. From a consideration of the mode of
formation of the large ray pits of Pinus, we see that
the two main divisions of the genus fall roughly into
two principal subgroups, one less specialized with one
or several small pits in each cross-field of the wood ray
and the other more highly specialized with large infre-
quent pits in thin-walled ray cells. These subgroups
grade into one another, but by recourse to other fea-
tures of anatomical specialization as well as to external
characters, a satisfactory basis for further subdivision
along true evolutionary lines is obtained.
Summary AND CONCLUSIONS
1. By a study of the anatomy of fossil and living
pines certain lines of descent may be somewhat clearly
discerned.
2. Cretaceous pines as well as Prepinus Jeffrey were
1 Conwentz, Monog. d. Balt. Bernsteinbaeume, pp. 55-56, Tab. XIV, 7,
Tab. X, 4.
No. 521] THE EVOLUTION OF PINUS 293
characterized by thick-walled ray parenchyma and pici-
form lateral ray pits, by the absence of marginal ray
tracheids and by abundant tangential pitting of the ~
autumnal tracheids.
3. The development of ray-tracheids, the disappear-
ance of thick-walled ray cells, the origin of large com-:
pound ray pits and the loss of tangential pitting in the.
autumnal tracheids are all features of the evolutionary
development of the pines of the present epoch.
4. The large lateral pits of the rays in modern species
of Pinus have taken their origin for the most part by
the fusion of small pits with distinct circular borders.
5. The hard and soft pines with very large lateral
ray pits are the most highly developed living pines.
The type of hard pines represented by P. resinosa in
North America and P. silvestris in Europe, represent
in the concurrent development of very large generally
solitary lateral ray pits, with dentate marginal ray
tracheids and the obliteration of tangential pitting in
the autumnal tracheids, except in the seedling and in
the woody axis of the. cone, the most highly developed
and specialized condition among living pines.
6. The nut pines of North America and Asia have
piciform lateral ray pits and thick-walled ray cells and
in these features approach most nearly to the conditions
of structure found in Cretaceous pines.
7. The hard pines of the United States, with the ex-
ception of P. resinosa, show a great range of variation
from piciform to compound lateral ray pits. The soft
pines present a parallel series of gradation in ray
pitting. ;
In conclusion, I wish to express my thanks to Pro-
fessor Jeffrey for material of Cretaceous and other
pines and for aid in securing the photomicrographs
‘with which this article is illustrated. To Professor
Jack I am indebted for specimens of the woods of
Asiatic pines and to Mr. E. W. Sinnott for the oppor-
tunity of examining serial sections of the seedlings and
cone-axes of a number of pines.
FACTS ABOUT THE ‘‘LOBSTER PEARL”
PROFESSOR FRANCIS H. HERRICK
‘ WESTERN RESERVE UNIVERSITY
TurovucH the kindness of Dr. H. M. Smith, of the
U. S. Bureau of Fisheries my attention was recently
called to reports of the discovery of a ‘‘lobster pearl,’’
which had a wide circulation in the newspaper press.
In an article credited to the New York Times, Mr.
Herman Meyer, a pearl dealer in New York, to whom
this object had been sent for examination, is reported to
have described it as follows:
As best I can see, the pearl has none of the laminated structure of
a pearl produced by a shell. But, while it seems one homogeneous
mass, at the same time it is as much a pearl as a lobster can produce,
and as true a pearl for a lobster as is a regular pearl for a shell.
Lobsters are not in-layers, and the inside meat of a lobster does not
move as does the inside of a pearl shell. In my opinion it is a lobster
pearl.
In reply to a letter of inquiry on the subject, Mr. Al-
fred Eno, of Jamaica, New York, gave this account of
the finding of the ‘‘pearl’’:
In July, 1907, accompanied by F. W. Denton, of Hollis, Long Island,
I was eating dinner at the Orient Point Inn, Orient Point, L. I., and
besides other things, we had some lobsters which had been caught in
Plum Gut, off the end of Orient Point, the day before. Mr. Dunton
broke open one of the claws of the lobster he was eating, and in biting
into the meat, his teeth came in contact with a hard substance
Mr. Eno kept this ‘‘hard substance’’ as a curiosity,
and two years later sent it to the dealer in New York,
who, as related above, pronounced it to be a true pearl.
The following further details were given to me in a
letter by Mr. Meyer:
The pearl was about 7 millimeters in diameter; nearly round, not
smooth; the color was a light manilla, about that of the inside of the
shell after boiling. The hardness was about 3; the texture was solid,
294
No.521] FACTS ABOUT THE “LOBSTER PEARL” 295
without layers, and the fracture was waxy but not brittle nor con-
choidal. It had no place where it seemed to be attached to anything,
and it had no lustre beyond that of beeswax. To all appearance it
seemed the same material as the inside of the claw, without crystalline
structure and without layers. Every appearance of the pearl and the
manner of the finding, and the two men who found it indicated that it
was not a fake. I deal with many of these things, almost daily, and
could have determined that fact.
Later through the courtesy of Mr. Eno, I was able to
make a careful examination of the so-called ‘‘pearl,’’
and to secure the photographs, which are here shown.
While my findings, which will be now given in detail, do
not support the view expressed above—that we are deal-
ing with a true pearl-like body in any proper sense—
they in no way detract from the biological interest of
the object, which is without doubt unique.
Description.—The body called a ‘‘pearl’’ is chiefly re-
markable for its form, for when seen from one side or
pole it has the appearance of a
nearly symmetrical sphere, 11 milli-
meters in diameter (Fig. 1). That
it is not in reality regular, but has
a long axis at right angles to a flat-
tened side, is better seen by refer- oe gee Wa ea
ence to Figs. 2 and 3, in which the pear,” seen from side par-
object is represented four times its Aea axis of ingrowth.
natural size. Its absolute weight is
0.9785 gram.’ It is-of a light buff color, and in all essen-
tial respects resembles the shell of any lobster’s claw,
when seen from the inside, and in the dried state (Fig. 4).
The surface of the body is neither chalky nor waxy,
but shines faintly, and has a distinct punctate or granu-
lated appearance. The flattened pole or side, which
bears the marks of a knife, and was evidently once
rougher than now appears, represents, without any
1For this determination, as well as for the specific gravity of the
‘*pearl,’’ and shell of the lobster’s claw, I am indebted to my friend Pro-
fessor H. W. i Aan cer of Western Reserve University.
296 THE AMERICAN NATURALIST [VoL. XLIV
doubt, the original ‘‘stalk’’? or bond of union with the
rest of the shell. Close to this base rises a crest one
third of an inch long (seen to left of star in Fig. 3),
and from this a rather conspicuous furrow diverges and
passes diagonally up one side of the mass. In this
furrow close to what we regard as the base of attach-
ment, lies a large hair-pore (over star), which is visible
to the eye, and into which a needle-point can be easily
thrust, while around this base a dozen smaller but quite
similar hair-pores can be readily detected with a
magnifying glass.
seen from the side
ing an obligue groove runn it up from
the base of attachment. cae hair-pore
growth. Four times natural size. near the base is over the star.
The punctuate or granulated surface of the body
(Figs. 2 and 3) is seen upon microscopical examination
to be due to minute elevations, which are thickly and
rather uniformily distributed. Each of these elevations
is crater-like, having what appears like a central pore,
from which radiate very fine creases or strie.
The shell of the lobster, although apparently a solid
armor, is very sensitive, for it is virtually a strainer,
being penetrated in its every part with multitudes of
No.521] FACTS ABOUT THE “LOBSTER PEARL” 297
minute vertical canals, which give passage to either
sense-organs (sensory sete, bristles or ‘‘hairs’’), or to
glands (ducts of the tegumentary glands), and thus put
the soft and sensitive skin in direct relation to its outer
environment. The pores of the tegumental glands open
on crater-like elevations similar to those described
above, but lie far below the limits of visibility to the
naked eye. These glands themselves are usually not
over .15 millimeter in longest diameter, and while the
length of their ducts is not commonly more than .15
Pm. 4 P —— aph of oes inner easier of the shell, from the lower side of
the toothed claw, owing listers t. p.), which represent the hair- Rj
The larger satan areas ($. p.) near the margin are sieve-plates, which g
passage to hundreds of sete. Four times natural size
mm., plus the thickness of the shell at that point, their
diameter is only .008 mm. ‘The hair-pores, on the other
hand, are sometimes visible, being .15 mm. in diameter
or larger, while many are much smaller than this, and
when the shell from the under side of the big claws is
seen from the inside, they are found at the summit of
large blister-like elevations (Fig. 4), though too small
to show in the photograph. In other places, as in the
shell from the upper side of the big claws, the pores of
298 THE AMERICAN NATURALIST [Vou. XLIV
this type usually lie at the bottom of corresponding de-
pressions. We consider that the minute elevations on
the surface of the so-called pearl mark the positions of
tegumental glands, the only other possible conclusion
being that they represent extremely minute and no
longer functional hair-pores. In any case they prove
that the structure of this body tallies with that of the
rest of the shell.
It may be added that between the conspicuous ‘‘cra-
ters’’ of the more prominent and functional hair-pores
(on the inner surface of the shell of the big toothed
claw), innumerable smaller granulations occur which do
not appear to belong to functional sete or to glands, while
along the lower outer margin of this claw, where the
sete are bunched, each elevated area has the appearance
of a sieve, bearing hundreds of holes. Two of these
areas, which correspond to very marked depressions on
the outside of the shell appear at the upper right hand
side of Fig. 4 (s.p.), close to the outer margin of the
toothed claw, and near its tip. The magnification, how-
ever, is not sufficient to show the pore-canals. The
hard shell of the lobster is further vertically striated
and horizontally laminated, and the same laminated
structure can be seen at the base of the body in ques-
tion, where a knife has been applied.
The specific gravity of the sphere was found to be
1.45, and that of a part of the dried shell of a toothed
claw (from upper surface of propodus, near the hinge-
joint of a large hard-shelled individual) was 1.43.
It is thus evident that in color, texture, structure and
specific gravity, the body under analysis agrees with
the shell, being peculiar only in its form, and in the
position which it occupied in the meat of the claw. It
is not a ‘‘pearl’’ in any sense, but an integral part of
the shell, to which it was joined at its short stem or
base, until the claw was broken open by the finder.
Origin.—It is safe to say that no proper pearl can be
formed in a crustacean, and presumably in no other
No.521] FACTS ABOUT THE “LOBSTER PEARL” 299
arthropod, since the hard shell is a differentiated por-
tion of the outer ends of the epithelial cells themselves
and in direct organic connection with them, except un-
der the peculiar conditions which determine the molt.
The shell of a pearl-secreting mollusk, on the other
hand, is a true secretion product, to which deposits are
successively made by epithelial cells having a different
relation to the shell, which is never cast off. Assuming
that a foreign body could by any means find lodgment
between the hard and soft parts of a lobster’s skin, it
would not be free to move as is the case with a grain
of sand inserted beneath the mantle of a bivalve mol-
lusk, and if it did not immediately set up a process of
regeneration at the point of lesion, the foreign body
would be surely lost at the succeeding molt.
If the shell of the claw to which this spherical body
pertained had been preserved, its origin could have been
traced with greater certainty, but all things considered,
it seems to be a vagary of the process of regeneration,
due in all probability to some peculiar injury, leading
to an ingrowth or pocketing of the skin at that point,
instead of to the usual protuberance. It represents a
permanent ingrowth of a part of the shell, started in
all probability when this was soft, and not later
smoothed out or effaced at any subsequent molt. While
it would be impossible to prove that this body was not
formed, as we see it, during the interval between two
molts, it seems quite possible that it has survived more
than one casting of the shell, in which case we should
have a succession of ‘‘pearls,’’ similar to this one, but
probably forming a progressive series as regards their
size and solidity.
A eruder suggestion would be that this sphere repre-
sents one of the grinding tubercles or ‘‘ molar teeth’’
of the crusher claw, like the large proximal and usually
symmetrical tubercle of the dactyle, pressed into the
meat of the claw in some unaccountable manner, and not
later restored to a normal condition. The presence of
300 THE AMERICAN NATURALIST [Vou.XLIV
tegumental glands, assuming that these have been cor-
rectly identified in the body in question, might lend
some support to this idea, for the tubercles are formed
by fusion of the sharp teeth, near the apex of each of
which a tegumental gland is seen to open, up to the
fourth and to even later stages of development before
the adult types of claw have been differentiated. I
da 5 bf i
ingrowth being marked by arrow. ‘The horiz
pon canals (hair-pores or capillary ne of the t
only roughly indicated; a, area of ingrowth; ep, chitin-forming vias of
soft skin; h. s., hard shell; p. c., canals eee shell; mu, mu
am inclined, however, to regard the body as the result
of regeneration, due to injury, in the way suggested
above.
Reduced to the simplest expression, the ingrowth and
shell proper bore the relations shown in Fig. 5, where
the axis of invagination is marked by the arrow. The
ingrowth involves in succession the soft skin (dermis
and chitin-secretin epithelium), the calcified non-pig-
mented and pigmented strata, and the thin outer enamel
layer of the hard shell, but the superficial area of in-
No.521] FACTS ABOUT THE “LOBSTER PEARL” 301
growth (marked a) may be represented here as extended
too far below the surface. The relations, however, are
the same, whether this pocket is deep or shallow, and no
attempt is made to express any possible mechanical
conditions which might determine the inward rather
than outward direction of such a fold.
SHORTER ARTICLES AND CORRESPONDENCE
AN EIGHTEENTH CENTURY MICROSCOPE?
EARLY microscopes are uncommon and our knowledge of the
sequence of their forms is in part to be gained by random dis-
coveries. The instrument shown in the figure was obtained
recently from the antiquary Meyer in Ziirich (who said that it
had formed part of the collection of Sir Henry Angst), and it
is worthy of comment, both for its early date, and its admirable
preservation.
It dates, in all probability, from the early years of the eight-
eenth century. It resembles in essential regards John Mar-
shall’s? microscope of about 1700 and Hertel’s* of 1716. Indeed
it may possibly be slightly earlier than the Marshall instrument,
for in some regards it is more archaic. Thus it conserves the
tripod-shaped support, and lacks the mechanical focusing adjust-
ment. It is, moreover, not an instrument of common class in
which such features would be retained at a late date by reason
of economy, for its workmanship is throughout precise and ele-
gant. On the other hand, it is furnished with a sub-stage mirror
which suggests a transitional form to the Hertel stand. The
stage and the supports of the barrel are of brass, as well also as
the upper rim of the eyepiece, which is provided with a dust-
proof sliding cover, as in early spy-glasses. The barrel and its
supporting tube are of carton; the former is covered with green
paper which bears rings as guides for focusing, and gilt bands,
the latter is decorated with Chinese shagreen. The base of: the
barrel, the mounting of the objectives and the region of the eye-
piece are of ebony. The base of the stand is octagonal, orna-
mented with moulding and furnished with a drawer for acces-
sories. It is quite similar to the Marshall instrument in this re-
gard, and in the turned supports of the eyepiece and of the ob-
jective.
There is but one eyepiece, its lenses measuring 1 inch and
1? inches in diameter, and it can not be removed from the stand.
* Recently presented to the American Museum of Natural History.
2Cf. Harris’s ‘‘Lexicon Technicum,’’ 1704, and figured by Carpenter
(VIL. ed.), 1891, p. 136.
Op. cit., pp. 137-138.
302
No. 521] SHORTER ARTICLES AND CORRESPONDENCE 303
There are five objectives, numbered, of which No. 1 is the high-
est. The power of magnification is as follows:
Eyepiece and objective 520 diameters (at 10 inches).
Eyepiece and objective 4 = 28 diameters (at 10 inches).
Eyepiece and objective 3 = 50 ey (at 10 inches).
Eyepiece and objective 2 = (broken)
Eyepiece and objective 1 = 330 a. (at 10 inches).
The lenses are simple (achromatic doublets dating only from
the early nineteenth century) and are diaphragmed extensively.
304 THE AMERICAN NATURALIST [Vou. XLIV
In fact, the lens of the highest objective is enclosed in a brass
eapsule which is perforated on either side, the perforations
measuring about 1⁄5 of an inch in diameter. With the highest
power there is an extraordinary working distanee—one eighth
of an inch. The maximum magnification, by the way, corre-
sponds roughly with that of a modern Leitz microscope, having
a No. 6 objective and No. 1 eyepiece.”
The accessories include stage-forceps, a small bull’s-eye con-
denser, a hand lens, forceps, extra concave mirror, a long
handle (?), a plano-coneave lens, and ten objects mounted dry
in sockets in a wheel-like carrier. The objects are still in place
and include pollen, flea, wing of fly, spider and insect scales.
BASHFORD DEAN.
ses acs nrc A BARNACLE COMMENSAL IN THE
ROAT OF THE LOGGERHEAD TURTLE
While investigating the parasites of the loggerhead, Ca-
retta caretta, at the Marine Laboratory of the Carnegie Insti-
tution at Tortugas, Florida, Professor Edwin Linton found
numerous small barnacles partially imbedded in the mucous
membrane of the upper end of the gullet. Many sessile bar-
nacles are known to live externally on marine turtles, whales,
ete., but up to this time none has been known living internally.’
One group of Cirripedia, the Rhizocephala, consists wholly of
parasitic forms which penetrate their crustacean hosts through
the external integument. The barnacle discovered by Professor
Linton which we will call Stomatolepas, seems to be the first
commensal form of the thoracic cirripedes.
Stomatolepas has about the size and shape of a split pea, the
oral surface being flattened. The calcareous walls form a shallow
bowl which is imbedded about half of its depth in the membrane
of the gullet or posterior part of the mouth of the host.
Stomatolepas pregustator n. sp.
The walls form a very broad, shallow cup, nearly circular in
contour, and about twice as wide at the opening as at the base.
The base is flat, circular, excessively thin, but sufficiently calci-
fied to be rigid and retain its shape when dried. The plates of
the wall are composed of two layers, an inner layer, thin, dense
and transparent, and an outer covering of several layers of thin-
1 The stalked barnacle Dichelaspis lives in the gill cavities of crabs, but
is not truly parasitic or commensal.
No. 521] SHORTER ARTICLES AND CORRESPONDENCE 305
walled cells. Externally a shallow radial sulcus in the cellular
surface marks the sutures between the plates. Each plate has a
triangular smooth median area at the base, where the outer cel-
lular layer is lacking, and the arched projecting upper ends of
the plates also lack the cellular layer. The summits of the
rostral and lateral plates are broader than the bases and strongly
arched; the cardinal plate projects less above the cellular
Ñ ny
Nd
et
Wili
ay
N
Fic. 1. Stomatolepas pregustator, lateral view and diagram of the oral face.
layer and is lower than the others. Internally the plates of the
wall are glossy, show no sheath, and are transversely ridged, the
ridges very narrow, parted by wide smooth intervals and about
twelve to fifteen in number; the basal fourth or third of each
plate is smooth.
Length of the walls 6.7, diam. 6, height 3 mm.
The opereular plates protect less than half the area of the
orifice, are very thin, glossy, white and smooth both outside and
within. They are long and narrow, the terga in contact with the
scuta but not articulated or interlocking in any way. The scuta
are longer than the terga, tapering to a point at the rostral end,
rounded at the tergal end.
The cirri are rather short. The first has unequal rami of 8
and 12 segments; the rest have subequal rami, the sixth pair
having 20 and 22 segments. The segments are armed with two
pairs of long spines, and on some of the median segments a third
extremely minute pair. Posteriorly there is a pair of small
spines at the distal angle of each segment.
The penis is about as long as the cirri, very densely annulate,
bearing very few minute hairs. There is a dense terminal pencil
of very short hairs.
The mandible has four large spines and a blunt, multispinose
lower angle. The maxilla has two large spines above followed by
a small notch, below which there are 7 to 10 spines.
Stomatolepas belongs by its non-articulated scutum and ter-
306 THE AMERICAN NATURALIST [Vou. XLIV
gum to the subfamily Coronuline as defined by Gruvel, being
most closely related to the genera Tubicinella Lam., which lives
on the skin of whales, and Stephanolepas Fischer, a barnacle
which lives imbedded in the plates of Thalassochelys imbricata.
Both of these have the wall more or less tubular and conspicu-
ously annulated externally. In Stomatolepas the wall is de-
pressed and broadly bowl-shaped, and covered externally with
a mass of thin-walled cells.
Henry A. PILSBRY.
THE AGE OF SPEED SIRES
The contribution by Professor F. R. Marshall in THE AMERI-
CAN NATURALIST for January, 1909, on the age of speed sires,
escaped my notice until recently called to my attention. In that
article Professor Marshall refers to the fact that I found the
average age of trotting sires to be 10.43 years, and that by ta-
king all sires in four generations of ancestors of 2:10 trotters I
found the average age at approximately 14 years.
Professor Marshall objects to this comparison as not being a
fair one on the ground that by going back four generations
from our 2:10 trotters we go back into the formative period of
the breed. This formative period, he asserts, followed the descent
from Hambletonian 10, foaled in 1849, and involved his sons,
which were used largely in the stud until old age. This he holds
produced an abnormal number of old sires at that period of his-
tory, and that by including them in my tables I was drawing
unwarranted conclusions from what was a mere incident. This
he reinforces by showing that the immediate sires of 242 trotters
in the 2:10 list were of the same age that I found for the normal
breeding age of 1,000 cases.
In this matter Professor Marshall labors under a misappre-
hension. The average age of 10.43 years for sires which I found
was the average as it existed in the ‘‘formative period’’ from
1840 to 1890. The ‘‘Register’’ from which they were taken was
published in 1892 and contained an alphabetical list of all stand-
ard horses from the earliest date up to immediately before 1892.
The tabulation was taken alphabetically from the index and the
10.43 is an accurate representation of what occurred when the
grandsires, great-grandsires and great-great-grandsires of our
2:10 trotters were living and being bred.
There is, in this matter, food for profound thought, and, with-
2 ‘í Monographie des Cirrhipédes on Thécostracés,’’ pp. 9, 270.
No. 521] SHORTER ARTICLES AND CORRESPONDENCE 307
out being too accurate in decimals, I will briefly state the situ-
ation as it exists. The immediate sires of our 2:10 trotters are
of an average age of 10.4 years. The grandsires are the im-
mediate sires of the sires and dams of 2:10 trotters, and as
immediate sires they should be 10.4 years of age, which was
the average age of sires at the time they became sires in these
pedigrees. But they are not. In these pedigrees they are 12.5
years of age. Evidently something has happened to disturb the
normal conditions.
Again, the great-grandsires were the immediate sires of the
grandsires, and they became such when the Hambletonian family
was breeding at 10.4 years between generations. But they did
not become sires in these pedigrees at their own average age at
reproduction, but at 13.5 years. Going back one more genera-
tion in these pedigrees we find the sires to be 14.5 years, going
another generation we find them at 15 years, and going still
another generation we find a total of 467 horses being sires at
an average age of 15.98 years!
Certainly, no one in his senses will believe that horses were
ever bred in this or any other country at such average ages as
these for any considerable body of them. Something extraordi-
nary has occurred, and that something deserves careful thought
and a reasonable explanation. That this matter is really extraor-
dinary I will illustrate by calling attention to another feature.
Some of the horses which appear as sires in the different gen-
erations were sent to the race track, while others were never
raced. When a horse is raced, he spends his early years on the
race track and is retired to the stud after his racing career is
over. As a consequence, of two brothers, one of which went to
the track and the other of which went directly to the stud, the
one which is raced becomes a sire at the higher average age, and
they should appear so in these pedigrees. But they do not.
The ages previously given are the ages of the sires which had
no standard records. The sires with records which appear in
these pedigrees appear in each and every generation at an aver-
age age of less than 10 years.
Now, why is this? No reference to a formative period is an
explanation when both kinds of horses were living and breeding
at the same time. In the best pedigrees, those horses which had
standard records appear at less than the average breeding age,
while those which had no records appear at about four years
above the average breeding age. CASPER L. REDFIELD.
NOTES AND LITERATURE
BIOMETRICS
Recent Quantitative Studies on Variation in Social Insects.—The
social insects (ants, bees, wasps and termites) because of the
differentiation of their populations into ‘‘castes,’’ distinguish-
able from one another in somatic characters, present a whole
series of interesting problems in variation, heredity and morpho-
genesis. These animals afford very alluring material with which
to undertake biometrical study of various problems within the
fields mentioned. It is a matter of comparative ease to get rela-
tively large numbers of individuals. The firm exoskeleton
makes measurement, and the preservation of material unchanged
for future measurement, comparatively easy. Finally, in addi-
tion to the wide variety of somatic structure to be found in the
several castes, the relation of these castes to sexual and asexual
modes of reproduction also adds to the intrinsic biological
interest and usefulness of the material for the study of general
problems. :
In view of these considerations it is somewhat surprising that
more biometric work has not been done with the social insects as
material. So far as the writer is aware there has as yet been
but one quantitative study of variation in ants, that of Kellogg
and Bell (10). With bees the case is somewhat better. Here
we have, besides the earlier work of Koschewnikow (11, 12) and
Bachmetjew (1, 2, 3, 4, 5 and 6) the careful quantitative studies
of Casteel and Phillips (7), Kellogg and Bell (loc. cit.) and
Kellogg (9). Miss Entemann’s (8) study of variation in the
coloration of Polistes, which was quantitative in character, was
the only study of the kind on wasps before 1907.
During the last two years two papers dealing with variation
in wasps have been published from Pearson’s Biometrie Labora-
tory. The first of these, by Wright, Lee and Pearson (16),
deals with the results of a study of the variation exhibited by
the individuals of the several castes (queens, drones and
workers) taken from a single nest of Vespa vulgaris. From the
material contained in this nest it was possible to get measure-
ments of 129 queens, 130 drones and 129 workers. The length
and greatest breadth of each wing were measured, as well as
the dimensions of various ‘‘cells’’ marked off by the wing veins.
Altogether seven absolute measurements were made and from
308
No. 521] NOTES AND LITERATURE 309
these six indices were calculated. The first point brought out
by the measurements is that the wings of queens are larger than
those of drones, and the drones in turn possess larger wings than
the workers. There are some differences in the proportions of
the wings in the three castes, though these differences are not
relatively so great as those in absolute size. There are only
slight differences, either in absolute size or proportions, between
the wings of the two sides of the body. All these are facts
easily enough ascertainable by direct observation. The biomet-
rical expression makes more precise and accurate what was
already known. In regard to the absolute size of the wing the
worker is absolutely and relatively more variable than the drone,
and the drone than the queen. In regard to the proportions of
the wing (as measured by the indices) this relation is nearly
reversed, though the differences are much smaller; the drone
is slightly less variable than the worker, and the queen is less
= variable than either. The degree of relative variability, as meas-
ured by the coefficient of variation, is exceedingly small for
some of the dimensions of the wasp’s wing. The mean coeffi-
cients for queens’ wings are for absolute dimensions 1.57 (right
wing) and 1.54 (left wing) and for indices 1.28 (right wing)
and 1.25 (left wing). These are among the smallest variabili-
ties yet recorded.
The highest correlations between wing dimensions were found
in the workers, and (with the exception of a single pair of
characters) the lowest correlations in the queens, the drones
taking an intermediate position. The index correlations were
found to be nearly all negligibly small. On the basis of this
result the suggestion is made that these wing proportions, as
given in the indices, ought to be useful taxonomic characters.
The point of greatest interest brought out by this first study
of wasp variation is the relative variability exhibited in the
different castes, as compared with what has been found for bees.
There can be no doubt apparently that in bees the drones are
more variable than the workers. This result was announced on
rather dubious statistical grounds by Casteel and Phillips (7),
criticized by Lutz (13), but abundantly confirmed by Kellogg
(9) and by Pearson’s (16, p. 422) reductions of the data of
Casteel and Phillips. In the wasp the drones are distinctly less
variable than the workers.
A second study of variation in wasps already referred to has
appeared quite recently. The work was done by Thomson, Bell
and Pearson (14) and deals with the comparative variability
310 THE AMERICAN NATURALIST [VoL. XLIV
of queens taken from a single nest, on the one hand, and of an
equally large sample of queens, presumably taken at random
from the ‘‘general population’’ of queens, on the other hand.
Such a comparison is obviously of a great deal of interest bio-
logically. First as to the source of material for the study: The
queens from a single nest were the same ones that were used
in the first study discussed above. The ‘‘general population’?
queens were obtained in the following way:
The queens for this second investigation were obtained in the spring
of 1908 in the neighborhood of Gerard’s Cross. As soon as the first
queen wasp appeared, a reward of 1 d. was offered for each queen
wasp brought, and considerably over 200 were then rapidly collected.
. The specimens came in small numbers, sometimes one at a time,
en alive, and there is no reason to doubt that they represent a genu-
ine sample of the queen wasps of the autumn of 1907, which survived
the winter and were starting in the spring of 1908 to establish their
nests.
This ‘‘general population’’ material collected in the way
described would appear to be open to serious criticism from
several points of view. In the first place, as pointed out by the
_ authors, these ‘‘ general population’’ queens represent a different
locality and season of the year from the single nest queens with
which they are compared. Nothing is known about the effect
of environmental and seasonal influences upon the characters
studied. In the sécond place, it is difficult to find in the sen-
tences quoted above, which is all the information that is offered
touching the point, any real concrete evidence that these queens
collected on the bounty system really were, as a matter of fact, a
truly random sample of the ‘‘general population’’ of queen
wasps. Since they all came from one restricted locality more
than a suspicion is raised, considering the habits of wasps and
the relative frequency and distribution of wasp nests, that they
may all have emanated from a very few original nests. If they
did the whole paper is vitiated. It is not of course meant to assert
that they did come from a few nests only, but it is desired merely
to point out that the authors of the paper apparently have no
evidence (and made no attempt to get any) that they did not
so originate. It might be held that the values of the biometrie
constants calculated for these queens constitute evidence that
they are a random sample of the general population. But this
is merely arguing in a circle. It is precisely equivalent to say-
ing that two and two make four because four is made by two
and two. The constants are, in the first instance, calculated and
No. 521] NOTES AND LITERATURE 311
their values are subsequently used in the discussion on the
assumption that the material is really a random sample of the
general population. The discussion of the biological import of
the constants has no significance if this assumption is not true.
This being so, it is not feasible to turn around and say that the
values of the constants prove the randomness of the material.
On the basis of this rather dubious material the discussion of
a very interesting question of inheritance is undertaken. The
characters dealt with are the same as those of the former paper.
The first point brought out is that there is a slight but definite
differentiation between the ‘‘single nest’’ and the ‘‘general pop-
ulation’’ queens. The authors state that they are not clear as
to what is the cause of the differentiation. The main point of
the paper turns on the relative variability of the two groups.
Taking first the standard deviations (the coefficients of variation
show the same thing), it appears that the ‘‘single nest’’ queens
are roughly only just about half as variable as the ‘‘general
population’’ queens. A long discussion follows regarding the
question of whether the amount of this reduction in variability
in the single nest is what would be expected on the basis of the
law of ancestral inheritance. The general outcome is that it is
not! There are, however, so many biological factors about which
the authors avowedly have no data at all, concerned in the pro-
duction and interpretation of the observed results, to say noth-
ing of the general difficulty about the randomness of the
‘‘oeneral population’’ sample, that the discussion fails to be very
convincing in any direction. This particular case well illus-
trates a tendency which seems likely to do a good deal of harm
to the biometrical cause, so far, at least, as biologists are con-
cerned. The whole discussion of inheritance in wasps in this
paper rests on a series of premises and assumptions regarding
wasp biology, which are made without any attempt whatever first
to learn by direct investigation the actual biological facts. This
method of developing a long and involved theoretical argument,
with very far-reaching ultimate conclusions, upon an exceedingly
slender basis of facts, gives such discussions of heredity a highly
academic, not to say Pickwickian, flavor. In general one can
not help feeling that if one becomes seized of a desire to know
how characters are inherited in wasps the direct and straight-
forward way to set about easing his intellectual pangs is to breed
wasps under controlled experimental conditions and observe the
results. The technical difficulties of dealing with this particular
material in this way would doubtless be considerable, but prob-
312 THE AMERICAN NATURALIST [Vou. XLIV
ably not absolutely insurmountable. In any event it would seem
that indirect methods of studying inheritance should be only a
sort of last resort when direct methods have failed or can not be
applied.
The correlations are also found to be reduced in the nest as
compared with the ‘‘general’’ population. The amount of this
reduction is shown to be that which would be expected as a
statistical consequence of the observed reduction in variability
of the one population compared with the other.
Warren’s (15) termite paper contains a wealth of interesting
biological data. It presents the constants caleulated from a very
extensive series of measurements of the character head breadth
in the different castes of several species of South African ter-
mites. The bulk of the data are from one species, Termes nata-
lensis. A typical nest of this species contains the following
kinds of individuals: (1) A single king and a single queen,
these being the only sexually mature forms present; (2) soldiers
of two sizes, asexual; (3) workers of two sizes, asexual; (4)
winged males and females, not sexually mature; (5) young or
immature members of castes (2), (3) and (4). Some of the
more interesting results which come out of this work are as
ollows:
There is considerable seasonal variation in the individuals of
the same nest. The mean is smallest and the absolute varia-
bility greatest in material taken in November, and the mean is
greatest and the absolute variability least in March material.
Warren offers the following explanation of this result:
This seasonal variation probably arises from two causes at least:
(1) the elimination of the physically unfit, (2) post- “adult” growth
With reference to the first cause it may be noticed that it is very prob-
able that more individuals arrive at maturity from August to November,
that is during the first rains, than at other seasons, and therefore the
stunted adults will be more abundant during this period, with the
result that the mean would be lowered and the standard deviation
would be raised. By the time that March arrives the small and weakly
individuals of the nest are likely to have died, and consequently the
mean will be raised and the standard deviation will be diminished. The
second, and perhaps more potent influence, is that the so-called
“ adults ” appear to grow to a certain extent even after their exoskele-
ton has become hard and yellow.
The workers of 7. natalensis are on the average less variable
than the soldiers. The ratio of worker variability to soldier
variability is about 0.8. The sexual castes are less variable than
the asexual, both in T. natalensis and as an average of the study
No. 521] NOTES AND LITERATURE 313
of other species of termites. The variability of a ‘‘general popu-
lation” of T. natalensis obtained by adding together random
samples of 100 individuals each (the small soldiers being the
caste chosen) from 30 different nests. The coefficient of vari-
ability obtained from this population was 7.02 as compared with
3.02 as the average coefficient for single families (i. e., nests).
There is thus a reduction here, as in the wasps, of about 50 per
cent. in variability in passing from ‘‘general population’’ to
single nest. The ‘‘inter-nest’’ correlation of the means between
any two castes is about 0.9. The author points out that:
It is curious that the correlation between similar castes (large and
small soldiers) does not appear to be greater than that between dis-
similar castes (small soldiers and large workers).
From a study of the correlation between the coefficients of varia-
tion it appears that:
In any given nest when one caste happens, say, to be particularly
variable, it does not follow that every other caste is correspondingly
variable. From a priori reasons one would have expected that the
variability of the different castes in a nest would have been closely
related, if the variability is to be regarded as an inherited character.
If, on the other hand, the variability is to be mainly referred to nur-
ture or to the general environmental conditions, the above results are
intelligible.
Bachmetjew (5, 6) has developed an intricate and highly
organized theory regarding the existence and origin of poly-
morphism in the normal bee colony. This theory is supposed
by its author to rest upon a solid ‘‘statistisch-analytische’’ foun-
dation. In reality this statistical ‘‘foundation’’ is of such char-
acter as to make one wonder at times whether the author (by
training a physicist and presumably familiar through that dis-
cipline with the elementary principles at least of the mathe-
matical theory of probability) is really serious, or whether he 1s
not perpetrating a great biometrie practical joke. The character
with which Bachmetjew has dealt in bees is the number of hooks
on the anterior margin of the posterior wings. His central thesis,
which he at once proves (?) and then forthwith applies to aid
in still greater biologico-metrical onslaughts, is to the effect that
if a group of individuals (size of group not specified and appar-
ently not regarded as in any way important) shows two observed
maxima of frequency, with respect to a character expressed in
integral or discrete units (e. g., hook number), then the eggs (or
seeds) from which the individuals of the group originated were
fertilized. If, on the other hand, but one maximum of frequency
314 THE AMERICAN NATURALIST [ Vou. XLIV
is to be observed, then the individuals developed parthenogenet-
ically. This neat, though somewhat far-reaching, generalization,
rests solely and simply on the location by inspection alone of
modes or maxima of frequency in samples of from about 50 to
150 individuals! Nowhere in Bachmetjew’s papers is there any
indication of such a concept as that the observed frequencies
might have a probable error ever having disturbed the placid
progress of the reasoning.
To give these comments point some of Bachmetjew’s frequency
distributions may be examined. Here are some distributions
supposed (with a mathematical naiveté probably nowhere to be
paralleled in scientific literature) to show two maxima of fre-_
quency at the points indicated by the bold faced type
(Bachmetjew (5)).
A. (p. 6) B. (p. 4) CT) D. (p. 9)
1 1 1 2
2 1 9 5
9 7 11 13
ll 28 27 19
21 31 - 27 15
21 18 22 15
21 9 11
16 2 2 80
5 2 2
2 99 110
1
110
It certainly demands the most consummate scientific insight
to discern why the two modes in A and C, for example, should
be located as they are. And again the unenlightened statistician
wonders what it is about the second 15 in D which makes it a
mode rather than the first 15. Is it possessed of a different
essence or aura, say a sort of transcendental ‘‘fifteenness’’?
Or again, to take but one more example, who would have sup-
posed that distribution E had two modes while F had but one?
(Bachmetjew (5)).
E. (p. 8) F. (p. 19)
2 1
5 1
10 1
“22 4
24 8
No. 521] NOTES AND LITERATURE 315
12 15
8 18
100 20
: 100
This is indeed esoteric biometry! So much so that it seems
hardly advisable to review the theoretical considerations which
are made to flow from the sort of statistics presented.
LITERATURE CITED
1. Bachmetjew, P. Ein Versuch, die Frage über die Parthenogenese der
Drohnen mittels der analytisch-statistiechen Methode zu lösen.
Allg. Zeitschr. für Entomol., Bd I
2. ——— Eine neue Methode zur Ismi der Frage über die Pisthowpetess
bei Drohnen. Russische Bienenzucht-Liste, Bd. VIII, Nr. 1.
Moskau, che (In Russian.)
Der Unterschied ae ee eae falschen Drohnen von den
ene Ts) betra set dio Standpunkt der an rap en ae
tischen Methode aus. e Bienenzucht-Liste, Bd.
4. oskau, 1904. (In pero Also publ hea in Gaia in
Insekt.-Börse, Bd. XXI, No. 47, pp. 371-372. 4,
4, ——— Kin Versuch, Datorer mit Dickel zu versöhnen. Zeitschr. für
Naturw. und Geograph., Nr. 4 and 5. Moskau, 1904. (In
ussian.)
Analytisch-statistische Untersuchungen über die Anzahl der
Die genes analytische Methode im Dienste der Bienenkunde.
(Hym. ntom. Zeitschr., 1910, pp. 15-22.
7. Casteel, D. B., and Phillips , E. F. Comparative Variability of Drones
and Workers of the Honey Bee. Biol. Bulletin, Vol. VI, pp. 18-
37, 1903
8. Enteman, Wilhelmine M. Coloration in Polistes. Carnegie
Institution of Washington, Publ. No. 19, 88 pp. 1904.
9. Kellogg, V. L. Variation in R PREEN Insects. Science,
N. S., Vol. XXIV, No. 622, pp. 695—699, 1906.
10. V. L., and Bell, R. G. Studies of Variation in
nsects. Proc. Wash. Acad. Sci., Vol. VI, pp. 20 1904.
11. dieu enna ane s nora zur Naturgeschichte der Biene (Apis
mellifica L.).—Nachricht. der Kais. Gesellsch. der Liebhaber der
N:
Sii, Anthropol., eF Ethnogr., Bd. XCIX; Arbeit. der Zool.
Abth., Ba. XIV, 1 Lief. (144 pp.) Moskau, 1900. (In Russian:
cited after Backine etjew.
12. ———- Materialien zu der Naturgeschichte der Biene deg. mellifica
L.) 2 Lieferung. Ueber den Polymorphismus bei Bienen und
anderen Insekten.. Ibid., Bd. XIV, 181 pp. rele 1905. (In
Russian; an abstract has been published by Bachmetjew in Zeitsch.
f. wiss. ‘Tascktenbiel. Bd. V, p. 246, 1909.)
13. Lutz, F. E. Variation in Bees. Biol. Bulletin, Vol. VI, pp. 217-219,
1904,
316 THE AMERICAN NATURALIST [Vou.XLIV
14. Thomson, E. Y., Bell, J., and Pearson, K. A Second Codperative Study
of Vespa vulgaris. Comparison of Queens of a Single Nest and
Queens of a General Population. Biometrika, Vol. VII, pp. 49-
15. Warren, E. Some Statistical Observations on Termites, mainly based
on the Work of the Late Mr. G. D. Haviland. Biometrika, Vol.
VI, pp. 329-347, 1909.
16. Wright, A., Lee, A., and Pearson, K. A Codperative Study of —
eens: and Workers in Vespa vulgaris. Biometrika, Vol. V, pp.
407-422, Pl. XXII, 1907.
RAYMOND PEARL,
EXPERIMENTAL ZOOLOGY
The Effects of Extirpation and of Transplantation of the Reproduc-
tive Organs in Insects.—Meisenheimer’ has carried on extensive
experiments with moths for the purpose of determining whether
the differentiation of the accessory genital organs and of secon-
dary sexual characters is dependent on the ovary and testis or
whether their development is independent of the sex glands. The
material used was chiefiy the moth Lymantria (Oeneria) dispar
L., which has a marked sexual dimorphism and recovers well from
the effects of operation. The caterpillar passes through five moults
before pupation, the first moult taking place about five days after
hatching, and each later one in from eight to twelve days, accord-
ing to temperature; pupation takes place in about six days after
the last moult and lasts for three or four weeks. The operations
consisted of removal of sex glands, removal of anlage of accessory
genital apparatus, transplantation of sex gland of the opposite
sex, and removal of wing anlage. The operations were done on
all six caterpillar stages, the extirpation of sex glands being done
by means of an electrice needle in the first two stages, and by a
knife in later stages. The mortality was very great, only 51
caterpillars surviving the electrical operation out of 1,250, and
176 out of 537 surviving when the organ was cut out.
In moths from caterpillars whose testes had been removed, the
vasa deferentia ended blindly; otherwise the accessory sexual
apparatus was perfectly normal. In one ease, the vasa defer-
entia had fused at their free ends, owing to their proximity at
the time of healing. The secondary sexual characters, such as
the size, coloring and markings of the wings, were of the normal’
male type. When, in addition to castration, the anlage of the
accessory sexual organs, including the vesiculæ seminales, ductus
ejaculatorius, penis and most of the vasa deferentia, was removed,
1 Experimentelle Studien zur Soma- und Geschlechts-Differenzierung.’’
Erster Beitrag. Von Prof. Johannes Meisenheimer. Jena, Gustav Fischer,
1909.
No. 521] NOTES AND LITERATURE 317
there was no trace of these organs in the moth; all that remained
of the sex apparatus was a rudiment of the vas deferens on each
side and the chitinous supports of the copulatory apparatus
whose anlage had not been removed. To make sure that the
lack of the accessory organs was not influenced by the absence
of the testes, some experiments were done in which the testes were
left intact and merely the anlage of the accessory organs was
removed. As a result, moths were obtained whose testes were
normal and the short ducts leading from them filled with mature
sperm, but none of the accessory apparatus was present whose
anlage had been removed. There was no influence on the sec-
ondary sexual characters when castration was followed by
removal of the anlage of the accessory organs.
In moths whose ovaries had been removed there was usually
no effect on the accessory sexual organs or on the secondary
sexual characters. Sometimes, however, there was a slight effect
on parts of the accessory apparatus, such as an increase in the
ramifications of the cement glands, an increase or a decrease in
the length of the oviducts. Likewise there was sometimes a
slight effect on the secondary sexual characters, in that the
ground color of the wings was somewhat darker than normal.
When the anlage of any part of the accessory sexual apparatus
was removed, that part was not present in the adult.
The transplantation of a testis into the body of a female from
which one ovary had been removed was successful in only one
case. The operation was done in the third caterpillar stage
when the testis is still quite small and at a low stage of develop-
ment. The testis developed normally in the body of the female
and was found to contain mature sperm. The ovary was also
well developed. The transplanted testis had no influence what-
ever on the external somatic characters, which were of the usual
female type. :
When one or both ovaries were transplanted into a castrated
male, the development of the ovary was usually normal. Some-
times one or two of the ovary tubes failed to develop, owing
probably to lack of room, since the ovaries were always best
developed in the largest males, where there was most space. In 20
out of 111 moths with transplanted ovaries, the ovaries united
with the vasa deferentia, one ovary with one vas deferens, or
two ovaries united with one vas deferens or, in two cases,
each ovary with a vas deferens. The histological structure of
both ovary and vas deferens was normal, but the eggs never
passed down the vas deferens. In one case, one testis was left
at the end of a vas deferens and an ovary inserted in the vas
318 THE AMERICAN NATURALIST [ Von. XLIV
deferens just below. They both developed normally, but the
duct served as an exit for the sperm only, not for the eggs. The
transplanted ovary had in no ease an influence on the secondary
sexual characters; the only difference between these moths and
normal males was the fact that the eggs made the abdomen bulge
somewhat.
Some experiments in transplanting were tried on Orgyia gono-
stigma because of its marked sexual dimorphism and because it
remains in the caterpillar stage for about eleven months. Only
two males survived the operation, and although the ovaries had
been in the male body from September 11 till June 20 and
were well developed, there was no evidence of any effect on
somatic characters which were of the typical male sort.
Investigations as to the effect of the operation on such psy-
chical characters as sexual instincts led to the conclusion that
these characters are independent of sex cells and of parts of the
sexual apparatus. In castrated moths, in moths deprived of
their copulation apparatus, and in males with transplanted
ovaries, the sexual instinct was found to be as strong as in
normal males.
In another series of experiments, the anlage of the wing, a
secondary sexual character, was removed at the time of castra-
tion in order to determine whether the new anlage laid down in
the absence of sex cells would have the same sexual character
as the old anlage laid down in the presence of the sex cells. In
the control series, in which the sex cells were left intact and the
anlage of the two wings of one side was removed after the second,
third and fourth moults it was found that in one fourth of the
cases there was no regeneration; in the rest, all amounts of regen-
eration occurred up to an almost complete wing, all of the regen-
erated wings being perfectly normal in markings which occurred
in the-same relative position as in the normal wing. From the
fact that the whole wing is present in miniature and not merely
the root of the wing is present, Meisenheimer concludes that the
wing has not grown out from the stump of the old anlage which
was left, but that a new anlage center has been laid down, per-
haps by the old stump which has gained new relations with the
tracheae. The difference in the amount of regeneration he
attributes not to the amount of tissue left in operation, but to
the length of time elapsing before pupation. In cases where
this was shortest, about the time for normal moths, no regenera-
tion took place; when this was somewhat longer (from 10 to
14 days longer) some regeneration took place; when this was
longest (from 17 to 37 days longer) almost complete regenera-
No. 521] NOTES AND LITERATURE 319
tion took place. The pupa period remained about the same as
normal, whence the conclusion is reached that regeneration takes
place during the caterpillar stage and differentiation during the
pupa stage. In the castrated series, in which the wing anlage
was removed, it was found that the wing developed its normal
sex character, although no sex cells were present. There was a
difference in the amount of regeneration just as in the control
series. Likewise in males with transplanted ovaries, the regen-
erated wing was of the normal male type, and exactly corre-
sponded with its unregenerated mate.
From these experiments Meisenheimer concludes that in these
moths primary sex cells have no influence on secondary sex char-
acters or on sexual instinct. He therefore does not agree with
the theory that internal secretions from the sex glands affect
the soma. Both primary and secondary sexual characters are to
be traced back to the young germ cells, since the secondary are
not influenced by the primary during ontogeny.
E. N. BROWNE.
ANTS
The last number in the Columbia Biological Series is a volume
by W. M. Wheeler* on ants. It is the largest number in the
series, containing nearly 700 pages, but the unusual interest of
the subject justifies the size of the publication. After an intro-
ductory account of ants as dominant insects, the author devotes
several chapters to their structure and development. Then fol-
ows a discussion of polymorphism in which the interesting
problem of the non-reproductive worker in relation to heredity
is fully elucidated. After this come chapters on the classifica-
tion and distribution of ants and on their geological history.
The remainder of the body of the text contains a most fascinating
account of the habits of ants. Following a consideration of the
habits of ants in general, of nest-building and of the ponerine
ants, the most primitive and generalized type of modern ants,
is a succession of chapters on special habits and relations.
These include accounts of the driver ants, the Huns and Tartars
of the insect world; the harvesting ants, which, though they are
grain-gatherers, are not strictly speaking grain-planters; the
fungus-growing ants, whose subterranean fungus-gardens are
fully described and beautifully illustrated ; the honey ants, some
of which serve their colonies as living receptacles for stored
sweets; and, finally, the slave-making ants, which in extreme
cases ~~ to be absolutely dependent upon their captive workers.
* Wheeler, W. M., ‘‘ Ants, their Structure, Development and Behavior,’’
New nay ‘The RER ER University Press, 1910, pp. xxv + 663; 286 figs.
320 THE AMERICAN NATURALIST — [Vou. XLIV
In appropriate places between the various chapters on these
special groups are interpolated chapters on the supposed mutual-
ism of ants and vascular plants, on myrmecophiles, of which
among arthropods alone 1,500 species are known, on parasites,
and on compound nests. The portion of the text dealing with
the habits of ants is concluded by three remarkable chapters on
the sensations, and instinctive and plastic behavior of ants,
which, as a body of mature judgments on this most subtile field
of animal investigation, is of the highest order. Any one who
wishes to reach sane conclusions in the study of the habits of
ants should ponder these chapters with care. The volume con-
tains five excellent appendices: the first, on methods of collecting
and studying ants; the second, a key to the subfamilies, genera
and subgenera of North American Formicide; the third, a list
of the deseribed ants of North America; the fourth, on the
extermination of noxious ants; and finally, a bibliography of
over 2,000 titles. An ample index brings the volume to a close.
The brief outline of the subject matter of the volume as already
given indicates the breadth of treatment accorded the material by
the author. Asa result the volume ought to find numerous read-
ers beyond the professionals. Its pages throw many side-lights on
human affairs which show that the sluggard is not the only one
that might profit from the ant. Although the volume is based
upon the studies of a world-wide range of myrmecologists, the
reader is met at every turn with the author’s extensive and inti-
mate first-hand acquaintance with his subject. This acquaint-
ance gives his critical comments unusual value.
In a book of such high general excellence it might seem ungra-
cious to point out minor defects. As a matter of fact, however,
the few that were noticed served only to increase the initial im-
pression of thoroughness and accuracy. The illustrations, which
are of the same high order as the text, are occasionally without
any indication as to magnification (original Figs. 35, 37, 38, 39,
etc.), and in a few other instances omissions occur, as in Fig.
271, in which the descriptive lettering of the legend is not
repeated in the figure. In the text on page 108 giantism is
probably a slip for the more usual gigantism. But even such
slight defects as these are rare and the book presents an unusually
clean appearance for a first edition. The treatment of the sub-
ject is so masterly and the material make-up of the volume so
excellent that the biologists of this country may well look with
pride upon this work as an American product.
G. H. PARKER.
9 CALLOWHILL STRERBT, PHILADELPHIA, PA.,
BOOKS WILLIAM J. GERHARD,
2209
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THE
AMERICAN NATURALIST
Voi. ALIY June, 1910 No. 522
THE BOTANICAL SOCIETY OF AMERICA!
I. THE NATURE OF PHYSIOLOGICAL
RESPONSE
BY THE LATE PROFESSOR CHARLES R. BARNES
UNIVERSITY OF CHICAGO
Livine plants could hardly have been observed at all
without recognition of the fact that they are affected by
external conditions. These effects, when first observed,
were undoubtedly interpreted as mere conditions of liv-
ing, and our interpretation to-day has hardly gone be-
yond this. A moderate temperature, an adequate supply
of water, and the normal light are necessary for green
plants; and when these conditions are suitable the gen-
eral behavior of the plant is affected. All its processes
have a healthy tone; it flourishes; and the factors which
operate to produce this condition are declared to be tonic.
When the effects of external agents are studied more
closely, several peculiarities appear. Even these tonic
factors are seen frequently to produce quite limited
changes in behavior, though they may act simultane-
ously upon all parts of the body. Especially is this the
case when there is some sudden change in the intensity
or direction of these factors. Thus if the air tempera-
ture falls a few degrees on some spring day when the
crocuses are in bloom, the perianth segments promptly
curve inwards and close the flower. Or if the sunlight is
1 Invitation papers read at the sixteenth annual meeting of the Botanical -
Society of America, Boston, 1909.
321
322 THE AMERICAN NATURALIST [Vou. XLIV
obscured by clouds, the dandelion heads are soon folded
together by the straightening up of the involucral bracts.
No other changes are visible, though others may be de-
tected by appropriate means.
Again, external agents may act on only a limited region
of the plant, in which case the obvious effects may be re-
stricted to some special part, either that immediately
acted upon or one at a greater or less distance from it.
Thus if the cotyledon alone of a Panicum seedling be
lighted from one side, the hypocotyl, 20 mm. or more
away, instead of continuing its equal growth, may curve
abruptly.
In these two cases of limited visible change, the phe-
nomena are explained by asserting that the protoplasm
is irritable and responds to an external change called a
stimulus. In fact, there is an inclination, after endowing
the protoplasm with such ‘‘ properties” as ‘‘irritabil-
ity,’’ ‘‘automaticity’”’ and ‘‘self-regulation,’’ to be satis-
fied with the words and there make an end. Such a tend-
ency, wide-spread in the prescientific days, undoubtedly
springs from the wonder with which one confronts an
uncomprehended intricate mechanism. It finds expres-
sion, for example, in a common saying about this or that
industrial machine: ‘‘It seems to have almost human in-
telligence.’’ Of course no one supposes the machine
really endowed with other than physical qualities, oper-
ating through the matter and the energy with which it
is supplied. Yet the vitalism, which dominated the
earlier years of physiology, even yet controls our speech
and our thinking, and indeed lately shows signs of re-
vival.
Vitalism, assuming living matter to be endowed with
special powers, called vital in distinction from physical,
is itself in part an expression of helplessness in the face
of an uncomprehended mechanism, the living body, and
in part an interpretation of nature in terms of our own
consciousness. To seek explanation in that direction is
to proceed from the simple to the complex; but the ex-
planation of phenomena must be a process of analysis,
No. 522] PHYSIOLOGICAL RESPONSE 323
not of synthesis, and so of necessity proceeds in the other
direction. We may not believe it possible to account for
the behavior of living things by considering them as
mechanisms whose actions are to be described in terms of
matter and energy; and certainly it is not possible to do '
this now for any but the simplest actions. Yet it must
not be forgotten that all the progress that has been made
has been made in this direction; so that it commends
itself to us both by the a priori and the inductive method.
The phenomena of response are probably the most
complicated to be seen in the plant, and as yet we are far
from being able to describe them completely in terms of
physics and chemistry. I purpose only to present some
suggestions on the nature of these phenomena, as a con-
tribution toward the mechanistic conception of the plant,
in the hope that this presentation may help to rid us of
some of the subconscious vitalistic notions that are apt
to cling so persistently about our thought and speech.
First let us consider the relation of the phenomena of
response in living and non-living matter. To speak of
response by non-living matter can occasion no surprise.
Sachs, long ago, in his ‘‘Lectures on the Physiology of
Plants,’’ pointed out the fact that response is not pecu-
liar to living things, citing as an example the crystals of
the yellow iodide of mercury, which change their con-
stitution and color when stimulated by various agents—
a scratch sufficing to initiate a change which spreads
gradually through the whole. Many other, substances
behave similarly. To explain such a change we predicate
a state of metastable molecular equilibrium, the upset-
ting of which at one point incites a spreading disturb-
ance, as a row of properly spaced blocks fall.
There is another sort of response in non-living matter,
which is conditioned by external factors. In moist air
many anhydrous salts and oxids unite with water, and in
some cases in proportions differing with the amount of
the vapor pressure. Thus, anhydrous copper sulfate, at
a temperature of 50° C. with the vapor pressure gradu-
ally increasing from zero, would take up one molecule of
324 THE AMERICAN NATURALIST [ Vou. XLIV
water and become the monohydrate as soon as the vapor
pressure reached 4.5 mm. of mercury. As soon as it
reaches 30 mm. the monohydrate takes up two more mole-
cules and becomes the trihydrate; while at 47 mm. and
above the trihydrate adds two more molecules and be-
comes the pentahydrate. Conversely, should the vapor
pressure fall below 47 mm., the pentahydrate loses water
and is transformed into the trihydrate, and so on. The
constitution of the copper sulfate, in fact, precisely re-
sponds to the vapor pressure of water around it. Many
like cases might be cited. The peculiarity of these is that
while the external factor may change steadily, the phys-
ical response will be discontinuous. Among the multi-
farious phenomena of irritability in plants are some
which are so nearly parallel to the behavior just de-
scribed as to suggest an analogous causation.
It is possible that the application of the term irritabil-
ity to the behavior of crystals will seem an unwise strain-
ing of its usual sense. Irritability has often been
enumerated among the distinguishing properties of
protoplasm. Even Sachs wrote:
Irritability is the great distinguishing characteristie of living organ-
isms; the dead organism is dead simply because it has lost its irritability.
But if we are to consider irritability as a property—
a characteristic—of protoplasm, it must be understood
to be a conditional property, as strictly limited by cir-
cumstances as are the properties of non-living matter.
Steel may be highly tenacious at certain temperatures;
but at the temperature of liquid air it is as brittle as
glass and can be pulverized by a blow. A frond of
Laminaria when wet is a tough flexible strap, but when
dry it is so rigid and brittle that it can be broken to frag-
ments by slight bending. Many a plant is clearly irri-
table at moderate temperatures when well watered and
lighted, but loses its irritability completely under adverse
conditions. Becquerel has dried seeds for six months in
a vacuum with barium hydroxid at 40°, sealed them for
a year in a glass tube exhausted to 0.002 mm. of mer-
No. 522] PHYSIOLOGICAL RESPONSE 325
eury, kept them in liquid air at a temperature of — 190°
for three weeks and in liquid hydrogen (— 250°) for
three days. Is it possible to conceive of irritability ex-
isting under such conditions? Is it, indeed, possible to
conceive of life as latent? I think not. Irritability must
be counted as completely lost during this time, and as
regained when the seeds germinated, as they did when
suitable conditions were furnished. To emphasize the
conditional nature of this quality, it may be better to
describe protoplasm when irritable as in a state or con-
dition, instead of following the example of the physicist
in saying that it possesses the property of irritability,
of which it may be as surely dispossessed as steel may be
of its tenacity.
Of recent years Bose has the merit of having insisted
upon the essential similarity of response in living and
in non-living matter. His ‘‘Plant Response’’ and ‘‘ Com-
parative Electro-physiology’’ are based upon this con-
ception; and though they contain much that can not be
approved, I am in complete accord with the thesis that
plants are intelligible only as mechanisms whose be-
havior, though more complicated than that of non-living
systems, is to be described by analogous laws.
While recognizing the essential unity manifest in the
behavior of all matter, we must nevertheless discriminate
between physical and physiological response. It is not
possible, however, to use these terms as they have been
used, even by Bose, to designate, respectively, the re-
sponse of non-living and living matter, since many of the
responses of organisms are purely physical. Physical
response, as I conceive it, is marked by the fact that the
energy applied to the body is a full measure of the effect
produced. Thus, when the conductivity of a selenium
plate is altered by light, the molecular disturbance (if
we so explain it) is initiated by the radiant energy, and
the effect is precisely measured by the energy applied
from the outside. The selenium contributes nothing. It
is acted upon, and its condition is altered for the time
326 THE AMERICAN NATURALIST (Vou. XLIV
being, by the external agent. The effect dies out shortly
after the agent ceases to act. Whether there is a loss of
energy or a gain, no further change ensues in the system,
unless it is acted upon from the outside.
Physiological response, on the other hand, though at
bottom of the same sort, differs in that the external agent
produces an upset that releases energy previously ac-
cumulated, so that the effect exceeds that due to the ini-
tial energy acting upon the organism. That is why, in-
deed, the term stimulus was originally applied to such an
agent; it brings into action energy often vastly greater
than its own. In this case there is a run-down of energy.
The system contains less than before by as much work as
has been done in response to the stimulus. Repeated
responses lead to exhaustion of the accumulated energy,
when further stimulation is impotent. To explain such a
situation Bose’s theory of molecular strain is inadequate ;
we are driven to take account of stored energy, and not
a direct supply. For if the depleted system be kept
under conditions as nearly uniform as possible, it pro-
ceeds to recover energy by the incorporation of new ma-
terial with its potential energy. The protoplast assimi-
lates food and presently is ready for new response to any
stimulus. It is the cyclic character of their’ energetics
that characterizes living things, no less in the phenomena
of response than in nutrition.
Even a casual examination of the various responses of
an organism shows clearly that some of them are to be
classed with the physical and others with the physiolog-
ical, as above defined. If so, it is plain that it is not mere
responsiveness that marks living things, for non-living
matter responds; it is the ability after a loss of energy
by response to regain, by the aid of the environment, a
condition which makes response possible once more.
This is no mere restoration of a molecular equilibrium
which has been disturbed or relief from molecular strain ;
it involves acquisition of energy. How far this is due to
a direct intake of energy and how far to the utilization of
potential energy in available foods, our present knowl-
No. 522] PHYSIOLOGICAL RESPONSE 327
edge of the energetics of plants does not enable us to de-
cide. Certainly we can not accept the source proposed
by Bose, when he writes:
And now we see that the fine ramifications of fibrovascular elements
over as wide an area as possible in the leaf provides a virtual catehment
basin for the reception of stimulus. The expanded lamina is thus not
merely a specialized structure for the purpose of photosynthesis, but
also a sensitive area for the absorption of stimulus, the effeet of which
is gathered into larger and larger nerve trunks in the course of its
transmission downwards into the body of the plant.
It is of course possible to use the term stimulus to
designate any external or internal agent that produces an
effect upon the organism, and response for the effect
produced; but that use of the terms tends to confusion.
Yet, besides the erratic treatises of Bose, some recent
text-books use the words in this way. One, for example,
reads: ‘‘Responses to water stimuli.—The primary re-
sponses of the plant to the water of the habitat are four:
namely, absorption, diffusion, transport, and transpira-
tion.” It is hardly necessary to point out that if such
processes are responses, then every change that occurs
in nature is a response and every agent a stimulus. By
such a usage we should lose the whole value of the dis-
crimination embodied in the terms.
The less clearly plant processes are conditioned ey the
environment, the more likely they are to be reckoned
responses to stimuli. Growth, for example, is often con-
sidered a response to stimuli; but it seems most likely
that it is quantitatively deiseniiied by various factors
(turgor, temperature, oxygen, food, ete.), any one of
which may limit it. Stimulation by gravity or light may
be an added factor, interlocking with one or more of
them, and, by inducing local variation in the rate of
growth, producing curvature; which is obviously a
physiological response, for when the effect of the stimu-
lus passes away the ordinary rate may be resumed.
In considering the energetics of response, it is essen-
tial not to forget that many stimuli inhibit actions going
on at the time excitation occurs. There are many famil-
iar examples of this among animals, but few in plants.
328 THE AMERICAN NATURALIST [Vou. XLIV
One well known is the interference of stimuli in tendrils.
As Fitting showed, friction on the dorsal side of tendrils
which usually curve after irritation of the ventral side,
inhibits the curvature, not by setting up a countervailing
rate of growth, for it apparently has no power to influ-
ence growth, but by interfering with the reaction some-
where between perception and the growth response.
Here, if the stimulus were a source of energy, or limited
the reaction, the double excitation should produce a
doubly strong response. Nor can the well-known inter-
ference of light or sound waves in unlike phases be cited
as an analogy of the inhibition in this case, because no
such superposition is possible. It must be admitted that
in cases of this kind the energy of the stimulus is not
directly related to the response.
Of course, in urging this I must not be understood as
denying that the excitation is often proportional to the
intensity and duration of the stimulus, and that the final
response may be influenced by the amount of excitation ;
the point is only that potential energy is released in
amounts not at present referable quantitatively to that of
the stimulus.
On analyzing the varied reactions to stimuli, it will be
found in many cases that it is possible to recognize two
well-marked phases, which may be designated primary
and secondary. In other cases no such distinction can be
made. One of the primary phases of response is known
as perception, a word which, as used by plant physiolo-
gists, is entirely without psychological implications.
Whatever change in the protoplasm is connoted by that
term takes place almost instantly, as shown by the phe- ~
nomena of summation. Stimuli of extremely brief dura-
tion—say a small fraction of a second—so transient that
they produce no observable effect, nevertheless, if re-
peated at proper intervals, finally give rise to a reaction.
The brevity of each period of stimulation gives indica-
tion of the speed of the perception change; for if no
effect were produced by a single stimulus, repetition
could have no effect.
No. 522] PHYSIOLOGICAL RESPONSE 329
Another primary phase of response is the propagation
of the excitation. The disturbance called perception
propagates itself, that is, it initiates in adjacent material
a corresponding change, progressing from point to point,
as shown by secondary effects produced at a greater or
less distance from the point where the stimulus is ap-
plied. The precise character of the change itself has
been little studied in plants, though the rate of propaga-
tion is known to be of the same order of magnitude as
that in the nerves of the lower animals—say 1 to 10 mm.
per second.
The secondary phase of response is manifested either
separately by turgor mechanisms and by growth mechan-
isms, or by the two conjointly. In turgor mechanisms
altered turgor of the cells in a definite region causes dis-
placement of parts attached. In growth mechanisms
local differences in the rate of growth of the organ dis-
places the adjacent parts. When combined the earliest
displacement is due to turgor, and this is made permanent
by growth.
Examples are so familiar that they need hardly be
cited, and a single one of each will suffice. When the tip
of a leaflet of Mimosa is stimulated by burning with a
lens, the excitation is propagated to the petiolule of the
leaflet, the turgor of its upper and anterior cells is so re-
duced that those on the opposite side compress them,
bending the petiolule sharply and so carrying the leaflet
forward and upward. The disturbance may spread to
other leaflets and even to the base of the petiole, with
appropriate curvatures in each motor organ.
When a primary root is placed horizontal, perception
occurs mainly in the tip, the excitation is propagated
backward, and the secondary response appears as differ-
ential growth of the cells chiefly in the third and fourth
millimeter from the tip, which produces the well-known
curvature.
Though much diseussed, it is not clear whether the
secondary response of tendrils depends on a growth
mechanism or a turgor mechanism. I am inclined to be-
330 THE AMERICAN NATURALIST [ Vou. XLIV
lieve that there is here a combination, the first curvature
being due to a turgor change, which is fixed with unusual
promptness by growth.
The movements of minute motile organisms, whether
autonomous or induced, can hardly be analyzed, so inti-
mate are the relations of the primary and secondary
phases of response, if indeed they are separable.
All physiological responses when analyzed show the
same general relations, no matter how varied the stimuli
and the end reactions. If there were nothing more than
the general applicability of Weber’s law, this would be
enough to suggest that there is some fundamental unity
in the responses. There are, however, many other fea-
tures that point in the same direction. It is obvious that
the common factor is not to be found in the later phases
of the response, where the structure of the organ may
play a determinative rôle; nor in the direction from which
the stimulus acts, which is known to determine often the
direction of movement. Bose has sought to show that all
cells when stimulated exhibit two concomitant responses,
by which, it seems, he would account for all the phenom-
ena of plant life, even to the ascent of water! Without
assenting to his applications of the observations, we must
say that Bose has done good service in showing that a
mechanical contraction follows stimulation, and that
change in electric potential occurs simultaneously. This,
I think, we may consider established for a large number
of plants, and it is very likely true of all. A study of the
negative electric variation leaves us quite in the dark as
to its significance, and though we are constantly tempted
by electric analogies in the description of nervous phe-
nomena, we gain no real insight yet into the rôle of
electric stresses in organisms, because our knowledge of
their causation is too vague.
In concomitant contraction and electric variation we
have a two-phase phenomenon, which should be capable
of further analysis. Is there any simpler action—more
fundamental—which may produce both? To this ques-
tion the recent work of Lepeschkin and Tréndle, supple-
No. 522] PHYSIOLOGICAL RESPONSE 331
menting earlier investigations, suggests an answer.
Turgor variations have long been studied, but a reason
for them has been sought in vain. We now know that
various agents change the permeability of the protoplast
to solutes, and that this sensitiveness is not limited to the
specialized cells of a gland or a motor organ, but char-
acterizes even the mesophyll. That this behavior occurs
where there is no obvious relation to the functions of the
organ, suggests at once that it inheres in the protoplast
as a fundamental quality, in virtue of its chemical consti-
tution or its molecular structure. It is perfectly easy to
understand that this structure may be modified by the
radiant energy already known to alter the permeability
of the protoplast; and many other stimuli are of a kind
to influence the unstable chemical compounds that com-
pose protoplasm. If that estimate be verified by further
researches, we shall be justified in considering variability
in permeability as a basic property of protoplasts.
It will be evident enough that a change in permeability
will permit the escape of some of the cell sap, with con-
sequent shrinkage of the protoplast, stretched as it is by
osmotic pressure, so that Bose’s contraction would nat-
urally result. Whether the escape of the solutes would
account for the negative electric variation, I do not pre-
tend to say, for the present theories as to electromotive
force do not afford any light on the situation. Therefore,
until the relation of electric stresses to other phenomena
is better known, we must leave this question in abeyance.
The primary and secondary phases of a response may
be understood readily in conformity to this conception.
The sufficient stimulus or the summated excitation
changes the constitution of the protoplast, and this change
spreads along the protoplasmic lines of communica-
tion, until it reaches a region where the changed turgor
results in a curvature, either directly, as in turgor mech-
anisms, or indirectly, by altering the rate of growth, as
in growth mechanisms. That the turgor changes re-
ported in the root undergoing geotropic curvature appar-
ently do not harmonize with this theory is probably due
332 THE AMERICAN NATURALIST [Vou. XLIV
to the untimeliness of the observations. It is said that
when the curvature is taking place the turgor of the cells
on the concave side is unchanged and on the convex side
lowered. But by the time curvature is well under way,
the turgor conditions immediately following excitation
may have undergone complete alteration, if we may judge
from similar changes in motor organs. Thus, the orig-
inal turgor, lowered on excitation (according to theory)
by the increased permeability of the under side, may
have been regained, while the very growth itself of the
convex side may be responsible for the reduced turgor
then observed on that side.
The responses of recoil and orientation in motile or-
ganisms are easily interpretable in terms of this concep-
tion, and though the application is purely hypothetical,
it is no more so than the current explanations. Just such
a change as results in changed permeability of the walled
protoplast to solutes of the great vacuoles might take
place on the passage of a naked protoplast into or out of
a stimulation zone. How such a change can reverse the
mechanism of movement is not explicable at present; but
the new conception introduces no new difficulty. For ex-
ample: If a change in surface tension is predicated as
the result of excitation and the occasion of recoil, it is
just through some change in chemical constitution that
such an alteration in surface tension might come about.
If the organism be one which orients itself to one-sided
stimuli, orientation may as easily result from a local
change in constitution as in any of the ways assumed by
current theory.
No one is more keenly aware than I that these all are
matters of speculation. They are presented as such.
My hope is that they will direct attention to this phase of
plant behavior and will stimulate thought, which should
first clarify our conceptions, and then suggest lines of
research.
II. THE PLACE OF PLANT RESPONSES IN THE
CATEGORIES OF SENSITIVE REACTIONS
PROFESSOR FREDERICK C. NEWCOMBE
UNIVERSITY OF MICHIGAN
More than two decades ago in the hands of Darwin,
Sachs, Wiesner, Pfeffer, Strasburger, Stahl and others,
the principal sensitive reactions for both fixed and free-
moving plants had been determined. At that period, in
animal biology only a few scattered papers had appeared
on sensitive reactions. The zoologists approached this
study through human psychology; starting with intelli-
gence and reflexes in the highest animals, they cast a
glance now and then toward the lower metazoa, and
talked of reflexes and instinct. Plants, not standing in
the line of descent which has its climax in man, were
studied in an objective manner with no attempt to bring
their reactions into a scheme of comparative psychology.
For the past two decades more attention has been paid
to the study of behavior in the lowest animals, with the
result that a great body of literature has already arisen,
some of it tainted with anthropomorphism, but the most
of it describing simply and carefully the reactions of the
protozoa and the lower metazoa.
This independent activity on the part of the plant and
animal biologists has resulted in the upbuilding of two
almost independent bodies of literature on the behavior of
lower organisms. Such early workers in the field as Ver-
worn and Loeb compared and identified the reactions
which they saw in the lower animals with those already
published for plants; but as the zoologists have worked
on, and more workers have come into the field, there has
arisen among the botanists a feeling of uncertainty as
to the significance of the terminology employed by the
zoologists, and a hesitation in identifying plant reac-
tions with those of the lowest animals. Thus, Francis
333
334 THE AMERICAN NATURALIST [Vou. XLIV
Darwin, in his presidential address before the British
Association for the Advancement of Science in 1908,
intimates that he does not understand Loeb’s use of the
term ‘‘tropism.’’ Botanists, probably quite generally,
are in doubt as to whether Jennings’s ‘‘trial and error’?
description can be applied to plant reactions. The exist-
ence of these two bodies of literature, and the uncertainty
as to the significance of terms, calls, to my mind, for an
examination of the phenomena of response in plants and
in the lower animals, to the end that doubt may be re-
moved as to the applicability of the same terms to both
plant and animal response.
Proceeding to compare these two groups of organisms,
we may say that both have fixed and free-moving forms.
Most of the plants are fixed, and a group of their well-
known reactions which botanists call ‘‘tropisms’’ are
exactly simulated on the animal side by hydroids, as re-
corded by Loeb.? Geotropie and heliotropic bendings of
the so-called stems and the so-called roots of the hydroids
differ in no way from the manifestations of these phe-
nomena in the stems and roots of plants.
Most of the lower animals are free-moving, and it is
upon the phenomena of movement in these forms that
the most of the animal studies have been made. Among
plants, corresponding studies have been made upon the
movements of bacteria, antherozoids and the swarm-cells
of alge and fungi. A study of the literature describing
the behavior of the protozoa and of the free-moving
plants must convince one that the stimuli and the re-
sponses are the same in both divisions of organisms.
There are animals with amceboid movements and plants
with amoeboid movements, both animals and plants with
cilia, and both with flagella. We may go a step farther,
and consider the stimuli that influence the movements of
these plants and animals. We have learned that both are
directed in their behavior by gravitation, light, chem-
icals and the electric current. The behavior in the plant
1 Science, XXVIII, 353.
2 tí General Physintogy.? i L 103.
No. 522] PLANT RESPONSES 335
group can be described by the same terms as used for the
animal group.
Before proceeding farther in the comparison of plant
and animal responses, we must consider the relation of
responses in fixed forms to those in free-moving forms.
It is well known that botanists generally use the terms
‘*tropism’’ and ‘‘taxis’’ to distinguish movement in the
fixed organisms from that in the free-moving. Some zo-
ologists also, among them Verworn, observe the same
practise. The majority of zoologists, however, following
the lead of Loeb, omit the ‘‘taxis’’ designation wholly,
and include the movements of both fixed and free-moving
forms in the term ‘‘tropism.’’ This is merely a ques-
tion of terminology, and need not occupy our time here.
It is more important to consider whether the behavior of
the fixed and that of the free-moving lower organisms
are enough alike to be regarded as fundamentally the
same. We may cite an analogy by saying that a traction
engine may one hour be pulling a load along a road, and
the next hour it may be stationary and operating a
threshing machine. To enable it to do the one or the
other requires but a slight alteration in the form of con-
nection of its parts, a slight change in its mechanism.
A swarm cell of the alga, Ulothrix, may alter its direction
under the application of a slight stimulus, and swim
toward the source of light. It may, a short time later,
fix itself to the substratum, and now bend as a fixed or-
ganism toward the source of light. One can readily be-
lieve that the two reactions are the same except for the
difference in the mechanism.
Besides the evidence for the fundamental similarity of
sensitive processes in fixed and free-moving organisms
furnished by the foregoing example, is the evidence pre-
sented by the quality of relation of stimulus and response
in the two kinds of organisms: Both kinds of organisms,
according to their structure, show simple positive or neg-
ative movements toward or away from the source of stim-
ulation; both kinds are sensitive to the same kinds of
336 THE AMERICAN NATURALIST [Vor. XLIV
stimuli, such as gravitation, light and chemicals; and
both kinds vary their response according to their physio-
logical state. In the various published observations
which treat of the reactions of fixed and free-moving or-
ganisms, the authors regard the responses as belonging
to the same class; and we may so regard them here. It
might be said also, that the majority of reactions in the
middle and higher metazoa are regarded by some as the
same in kind, differing only in degree from the reactions
of the protozoa. With the more complex reactions of
the higher metazoa, botanists have little to do.
What now are the characteristics of these sensitive
phenomena in plants and animals by which we class such
phenomena together?
1. On both the plant and the protozoan side, the organ-
isms possess no nerve cells. We used to be taught that
for a reflex action there must be an afferent nerve, a
ganglion and an efferent nerve. Such a chain is no
longer necessary for a reflex according to definition.
Pfeffer speaks of reflex acts in plants, and Massart,
Jennings, Bohn and others expressly state that the
tropisms of plants and nerveless animals are to be denom-
inated reflexes, or, more specifically, non-nervous re-
flexes.
2. By the term ‘‘tropisms’’ (including ‘‘taxims’’),
the botanist has understood those direction movements
of plants due to external stimuli, such as gravitation,
light and chemicals. But this use of the term is now too
broad.
The zoologists apply the same term to similar move-
ments of the lower animals. But not all zoologists adopt
the definition of a tropism as the definition is understood
by the botanists. To the botanist, ‘‘tropism’’ always im-
plies a response due to what is known as the indirect ac-
tion of a stimulus; that is, the stimulus produces first an
excitation, the sunitbtion sets up a wave, or impulse,
which is transmitted to the reaction protoplasm, whose
action gives the sensitive response. The controversy
No. 522] PLANT RESPONSES 337
over the implied meaning of ‘‘tropism’’ as applied to
animals seems to have arisen mostly through the attempts
of Loeb and his followers to simplify the conception of
the sensitive processes, to conceive of the stimulus as
directly producing the reaction, as one might think of a
heliotropie curve in a marine annelid produced directly
by the sun’s rays shortening the muscles on the sunward
side. The controversy among the zoologists wages about
the terms direct and indirect. Indeed, the banners of the
opposing forces may be said to bear respectively but
these two mottoes. On the one side the herald has pro-
claimed these terms to the satisfaction of the botanists;
that is, all sensitive reactions are indirect; that is, they
are complex, the stimulus producing a change in the pro-
toplasm, local or wide-spread, and this excitation of pro-
toplasm producing an impulse, over a lesser or greater
distance, setting in operation, or releasing, energy which
brings the visible response. On the other side, the terms
are but obscurely defined, and the nearest we come to a
definition is that the excitation and the reaction are local.
Among plants there may be cases in which the excita-
tion and reaction are local, and there are certainly cases
in which a considerable part of the plant is affected.
Rothert, experimenting with the coleoptile of the oat,
found that he could induce positive heliotropism when
only the basal, motile, part was illuminated, the rest be-
ing shaded; or he could obtain the same reaction when
the basal part was shaded and only a millimeter of the
tip of the leaf was illuminated. In the former case, for
aught we know, the whole process was local; in the latter,
it certainly was not local. Yet there is no doubt in our
minds that the processes were the same in both cases.
In both cases there were excitation, conduction, reaction;
only in the latter case, the excitation was in a different
part of the plant, and the conduction was over a greater
stretch than in the former. Yet it is over the differences
which these two illustrations show that the controversy
has arisen over direct and indirect response. A case
338 THE AMERICAN NATURALIST [ Vou. XLIV
known to occur in plants seems to me to illustrate fairly
well the so-called direct response of the zoologists: The
leaves of some plants roll up when illuminated by the hot
sun, due to the loss of water on the illuminated side.
This is certainly direct, but most biologists would call it
a mechanical, and not a sensitive response.
It has already been said that botanists accept the in-
direct method as applying in all cases to plants; and
almost all zoologists take the same view with regard to
animal reactions. We may conclude, therefore, that the
term ‘‘tropism’’ may be used in the same sense for both
plants and animals. The ‘‘tropism’’ resulting from
direct action has not yet been demonstrated for either
plants or animals. This conception of the significance of
the term ‘‘tropism,’’ as presented in the foregoing para-
graphs, is not simple, but very complex; and in attempt-
ing to analyze the behavior of organisms, we meet with
several conditioning phenomena, some of which may now
be described. The terminology used in the following
paragraphs is taken mostly from the zoologists, and bot-
anists will note that the same terms are applicable to
plant response.
One of the most widely extended of these observed phe-
nomena is the variability of the response when the same
external conditions are operating. Thus, Strasburger
found the swarms-cells of Ulothrix and other alge, during
their early active period, positively heliotropic, but neg-
atively heliotropic during their later active period. The
change in disposition of the peduncle of the poppy, of the
Narcissus, and of the members of various other plants,
is familiar to all botanists. All of the foregoing changes
in disposition can be referred, for want of a clearer under-
standing, to internal changes incident to age. These
internal conditions which influence the response to ex-
ternal stimulus are called also the physiological state.
The foregoing examples are illustrations of the influence
of physiological state on response.
The physiological state may also be altered, and hence
No. 522 PLANT RESPONSES 339
the reaction of the organism may be altered, by an ex-
ternal agent which is not the stimulus to response. The
rhizomes of Adoxa and Circea, in normal surroundings
growing horizontally because of their diageotropism, be-
come positively geotropic when exposed to light, and
grow toward the earth. The rhizomes of some other
plants, in similar treatment, become negatively geotropic.
Experiments have shown that these changes of direction
in growth in these rhizomes are not heliotropic, but due
to a change in disposition toward gravitation. Light does
not cause the bending, but changes the physiological
state, and gravitation causes the bending. Another il-
lustration of a change in disposition due to external
agency is furnished by the behavior of seedling peas and
vetches which become more heliotropie when the atmos-
phere contains small quantities of illuminating gas, or of
carbon monoxid. Loeb found that Volvox, some crusta-
cean copepods and other organisms, are rendered more
responsive to light by putting a weak solution of carbon
dioxide, acetic or hydrochloric acid, in the water in which
they are swimming. This author suggests that this influ-
ence on the physiological state® is due to the acid pre-
venting the formation in the organism of some anti-posi-
tive substance, normally generated. This hypothesis may
not be supported by future study, but there is some evi-
dence offered in its behalf, and it is a worthy attempt to
come a step nearer to the intimate processes.
The ‘‘trial and error’’ hypothesis as applied by Jen-
nings to some phenomena of behavior in protozoa is de-
fined by him as ‘‘the selection through varied movements
of conditions not interfering with the physiological proc-
esses of the organism.’’* The term itself, ‘‘trial and
error,’’ has lately been abandoned by Jennings,°® but the
value of the hypothesis as describing behavior he still
maintains. It is plain to see that the so-called direction
movements, or tropisms, as they have been generally
* Archiv f. Physiol., 115, 1906, 564.
+‘ Behavior of the Lower Organisms,’’ 1906.
5 AMER. NATURALIST, October, 1909.
340 THE AMERICAN NATURALIST [ Vou. XLIV
recorded for our fixed plants, can not have their behavior
included in this category; for by them there is appar-
ently no selection through varied movements. Our typ-
ical plant tropisms show that one movement or curve, and
that is unvaryingly toward the assumption of the new
position of equilibrium. The response is what Bohn has
called resistless. The term is expressive, and may be
useful; but we must not forget that all reactions of lower
organisms are resistless.
There are recorded, however, the results of two series
of experiments with plants which seem to me to range
themselves with the phenomena described as ‘‘selection
through varied movements.’’ I refer to the establish-
ment of half-hourly geotropic rhythm in the stems of
Taraxacum and valerian, and of quarter-hourly helio-
tropic rhythm in the cotyledons of Phalaris and Avena,
by the work of Francis Darwin and Miss Pertz. If there
is doubt as to whether the rhythms just noted illustrate
the first part of Jennings’s hypothesis for the descrip-
tion of the origin of behavior, namely, ‘‘the selection
through varied movements of conditions not interfermg
with physiological processes,’’ there can, I believe, be no
doubt that the establishment of these rhythms illustrates
the second part of the hypothesis, namely, that the ‘‘reso-
lution of one physiological state into another becomes
more rapid after it has taken place a number of times.’’
The gradual shortening of the period of oscillation, in the
plants used by Darwin and Pertz, till the half-hourly or
quarter-hourly rhythm was established, seems to me to
express the more rapid resolution of one physiological
state into another. ©
Though the idea of trial and error seems capable of
application to but few of the recorded reactions of fixed
plants, it is descriptive of the movements of bacteria,
swarm-cells and spermatozoids. For these plants, by
varied movements, finally arrive at a condition of the en-
vironment which does not interfere with their physiolog-
ical processes.
No. 522] PLANT RESPONSES 341 -
Another descriptive for a group of phenomena in be-
havior, used in both botany and zoology, but in quite dif-
ferent senses, is differential sensibility. Pfeffer applies
this term to all of the tropistic processes of plants, in-
cluding the typical tropisms and the shock-movements;
and it is, as he says, true that it is only by a perception
of difference in the stimulus on the two sides of an or-
ganism that we obtain any tropism. On the other hand,
Nagel uses the same term—Unterschiedungsempfindung
—in application to the shock-movements alone. Jen-
nings, I believe, uses the term in Pfeffer’s sense, Loeb
and Bohn with nearly the same meaning as Jennings’s
trial and error idea, or, at least, they would claim that
the trial and error phenomena are a combination of
tropisms and responses to differential sensibility.
To Summarize: In considering the foregoing phenom-
ena, only the so-called direction movements of fixed or-
ganisms and the locomotory movements of free-swim-
ming organisms have been referred to.
The organisms considered—plants and protozoa—have
no nerve-cells, but nevertheless, their reactions are, and
may be, spoken of as non-nervous reflexes.
While the responses in fixed and free-moving organ-
isms are different in their external manifestations, the
relations of stimulus and response and the conditions of
operation of stimulus and response are much the same in
both classes of organisms.
The terminology as introduced and generally used by
botanists has been chosen as mere designation of the ob-
vious stimulus and the direction of movement of the
organism. Hence tropism or taxism is used to designate
all the responses which animal biologists, with closer at-
tention to details of behavior, have subdivided into a
larger number. In botany, therefore, the term tropism
should be used in a more restricted sense than at present.
In both plant and animal behavior, this term may be
restricted to those simple movements which result in
342 THE AMERICAN NATURALIST [ Vou. XLIV
placing the organism in a certain direction with reference
to the direction of the stimulus.
The term fright-movement or shock-movement or re-
cou (or a still better one) may be used to describe those
responses due to a sudden change in the environment.
Some of these shock-movements are doubtless tropisms,
but perhaps not all. These are the movements that are
due to differential sensibility (Unterschiedungsemp-
findung) in the sense of Loeb, and to transition stimula-
tion (Uebergangsreizung) in the sense of Pfeffer.
There might also be some designation for the series of
responses which Jennings attempted to name as ‘‘trial
and error,’’ a complex of tropisms and shock-movements,
influenced by a varying physiological state.
Very recently Bohn has proposed to account for all
behavior of lower organisms under four designations: |
mechanical reflexes (tropisms), vital rhythms (a group
of autonomous movements of the botanists), differential .
sensibility and associative phenomena.
The ideas contained in these terms are all illustrated
by plant behavior. But the terms are inadequate, for
they are not coordinate. Some of them refer to re-
sponses, some to physiological state.
Before closing, reference might be made to Semon’s
book, ‘‘Die Mneme,’’ the ideas in which, especially re-
garding associative phenomena in behavior, aid one in
gaining a possibly clearer conception of the origin of
some reactions of organisms.
Besides the reactions treated in the foregoing pages,
for which a harmony has been attempted between the
students of plant and animal behavior, we all know that
there are groups which need a better and more expressive
terminology than now is in use. As an illustration of
phenomena needing more precise terminology, I might
refer to the reactions known as epinasty and hyponasty.
A very complete and apparently adequate terminology
for all sensitive, non-nervous, reactions is given by Mas-
sart in Annales de l’Institut Pasteur, 1901, and a transla-
tion of the same in Biologischem Centralblatt, 22, 1902, 9.
THE LARVA AND SPAT OF THE CANADIAN
OYSTER
J. STAFFORD, M.A., PAD.
McGILL University
II. THe Spat
In the first part of this article, dealing with the larva,
I have already indicated that, in the progress of my re-
search, it soon became necessary to plan means of pro-
curing young oyster spat for comparison with my sup-
posed oyster larvæ before I could feel satisfied that the
latter were in reality larve of the oyster. Of the common
bivalve mollusks only Ostrea and Anomia live fixed to
objects of support, so that the matter has some appear-
ance of simplicity in the fact that all free-living forms
: may be eliminated. But careful examination of eel-grass,
rock-weed and other marine plants, of shells, stones,
timbers and other objects revealed no young spat, and I
was forced to wonder where the oyster secreted itself at
this stage of its life. I examined sand with the micro-
scope to find if, like many bivalves, the young oyster
might burrow for a time, but with no better result.
Bundles of brush were tied to submerged rocks, or
weighted with stones and sunk at various places. These
were examined at intervals but without success. Each
failure suggested some new possibility that required
examination and occasioned delay. Time was flying, it
was getting late in the season, and each day brought no
further progress. What stupendous obstacles present
themselves to the investigator and how simple after one
has once mastered them!
A copy of Jackson’s work,? procured for me at this
time by Professor Wright, was particularly opportune,
and I owe to it much by way of information and suggest-
1 AMER. Nat., XLIII, Jan., 1909, pp. 31-47.
? See literature 12 of part ay
343
344 THE AMERICAN NATURALIST [Vou. XLIV
EXPLANATION OF PLATE
The plate nian gare Sar “I, The Larva” was intended to be lithograpbed
of the Saye size but was reproduced smaller and lost detail. I find from meas-
urements the figures are magnified about 30 diameters. To agree whet it the
figures k x 3 of this plate, “ II. The Spat,” are magnified 30 diam
Fios. 1, 2, Young spat of Canadian si from the right WERT side |
as they occur attached. ETS 30 diamet
e khe Uy high, sho Gane ne and spat shells
Am 2. Spa hi bees The re val shell grows no larger, the spat shell
grows to the adult cae saad ston are sketched in but the liver is left out,
as it would obscure iad par
Fic. 3. Spat 1.5 mm, for aes on.
Figs. 4-12. a taravat sections of oyster spat 1 mm, high (compare Fig. 2),
viewed from aal tagai so that left and right of the figures correspond with the
observer, sections are in order from anterior to posterior but are not
successive. a shells ane been decalcified and are somewhat diagrammatic,
thin left and thick right va
Section rerig region of upper lip and transversely to anterior
Mamont of left inner Pyarzesje
Fic. 5. Thro outh, upon irked parts same as preceding. The lower lip
is borne by the eiere end of the abdomen (region of the foot).
. 6. Mouth open at ences closed in to esophagus at left. ` Rudiments of
Pek pi lower palps.
Fig. T opgi and tips of filaments of right ipak CREEA
Fic. 8. Abdomen with five liver-follicles about the opha
Fig; 9. Tarda eter of stom pik: dioak oa ok to enter it,
al be ey pe right and left stalks of liver. Three other gio ‘tollicles
ar well Soe inferior lobe of the stomach, the visceral ganglia an
the e ‘cies ‘hemib
Fie. 10. Thro papis aneio edge of adductor muscle, posterior end of gill.
1g. 11. Through adductor and tip of inferior lobe of stomach. Several
liver follicles.
Fic. 12. Posterior edge of adductor with rectum descendin
IGS. 13-18. Transverse sections of spat 2, 2.5, 3, 3.5, ne 5 mm, high. Not
1@. 13. aa gg mouth a 2 mm. spat, showing labial pa
FIG. of 2.5 mm, spat, rrio anter ior edge ag aaa, show-
ing the Has Minami slit ealag out fro supra-branchial cavity on the
m th
right side and the ru e fen the right sidro ad aii Right and left pies
filaments are cut longitudi
G
. 15. Similar pecans f 3 mm. spat but slightly in advance and cut short
above, TR rudiment of ieft Serer hemibranc
Fig. Slightly behind mouth of 3.5 mm. spat, cut off a to show ali
four abil Salen: sae ile and portion of stomach abov
Fie oug spat, showing septa between piis hrasti cavi-
ties of ta and pria kenaan the position of the original ctenidial axis.
Fic. 18. Section ve 5mm. spat through adductor muscle and eh ganglia,
The upper free edges of the mantle right and left of the rectum are very irreg-
ular. The branchial septa stop short of this section so that the supra-branchial
cavity is es above all four hemibranchs.
a, anus; ab, abdomen; be, rer 69 al apart bs, branchial septum; bv,
blood vessel; gf, gill filament; i, stine; l, liver, lig, left inner hemibranch
(gill) ; i — r lip; Ip, lower ioe oan, Is, left oat of prodissoconch (larval
shell) ; Is’, left valve of dissoconch (spat shell); m, mantle; mo, mouth; mt,
h
mantle vole cle; oe, esophagus; pd, posterior adductor cle; r, rectum; rig,
right inner “oemibranch se ; rs, right prodissoconch; rs’, _ gag iva
prodissoco: 8’, dissoconch; sbe, caus nehial cham sbs, ra-
sup
branchial slit; es aa as upper lip; up, upper labial mini vg, visceral
ganglia; wt, water tube
an WS
ea thas
BP
r
346 THE AMERICAN NATURALIST [Vou. XLIV
iveness. The method of putting out glass*® for the re-
ception of fixed forms of animal life I had already be-
come acquainted with at St. Andrews while working on
.the clam, but the present was the occasion to try every
means that could be devised and quickly applied. I ac-
cordingly took what objects could be easily procured and
constructed and set out traps calculated to capture full-
grown larval oysters at the time of their fixation. The
idea is the same throughout all forms of the method; the
particular turn in application was my own. Window-
glass was cut into strips 26 inches so as not to be too
big to use on the stage of a compound microscope, the ad-
vantage of glass being that one can use either transmitted.
or reflected light and can turn it over so as to see, through
the glass, the attached side of the oyster. These strips
were stood on end in deep erocks, about a dozen in each
crock, and kept from falling against one another by wire
racks, the object of placing them vertical being to mini-
mize the aggregation of sediment on their surfaces. The
traps were then planted at various places where there
were oysters—off Curtain Island where the oysters were
large, and off Ram Island Point where there were many
sizes of young oysters. The crocks were sunk in gravel
just below low-tide level and made secure against the
buoyant force of water and the lateral action of waves
and currents by building stones around them but leaving
the tops open. It was thought that larve, either swim-
ming about or swept about by the waves, might drop into
the crocks where the water would be comparatively still
and find it easy to cling to the glass during the first stages
of fixation.
Ram Island Point appeared to be the most favorable
place and that was about six miles from the station, but
daily visits were made, the strips of glass were one by
* Ryder, Comm. Fish. Maryland, 1881, p. 57; Bull. U. S. Fish Comm.,
1882 (1883), p. 383. Horst, Bull. U. S. Fish Comm., 1882 (1883), p. 165;
S. Fish Comm., 1884 (1886), p. 906. Möbius, Zool. Anz., Jan. 22,
1883. Winslow, Bull. U. S. Fish Comm., 1884, p. 354. Jackson, Science,
1888, p. 230 (Vol. XI, No. 275); Mem. Bost. Soc. Nat. Hist., 1890, p. 285.
No. 522 ` THE CANADIAN OYSTER 347
one withdrawn and examined with a lens, and whenever
a suspicious looking speck was observed the glass was
put in a pail of sea-water and taken to the station to be
examined with a compound microscope.
The strips soon became dirty, receiving a slimy coat
speckled with sediment, plants and animals. There were
bacteria, diatoms, algæ, protozoa, sponge-spicules, hy-
droids, polyzoon-colonies, worm-larve, crustacean larve,
small snails, ete. It seemed as if everything but oysters
could be obtained. So far as I saw, I had neglected noth-
ing that might contribute to the result in view. Could it
be that my suspected larve were not oysters, that there
were no oyster larve or oyster eggs in the water! Once
more I was bewildered.
At length, on the sixteenth of August, I discovered a
single minute oyster-spat, bearing unmistakable marks
of recognition and enclosing within the lately deposited
spat-shell the prodissoconch of the free-swimming larva.
On the nineteenth I found a second (Fig. 3), and on the
twenty-second a third (Fig. 1). Everything speedily þe-
came clear. My experiments had been running ahead
of nature. Oyster larve had been in the water, but they
were not ready to transform into spat. They had to
wait their time. On the thirty-first of August a fourth
was taken.
After finding the first oyster-spat on glass I at once
directed increased attention to natural marine objects
and on the second of September I found a spat on the
surface of a half-grown oyster-shell. From this time for-
wards they were to be found in increasing numbers and
on various objects and, after being once shown them, the
deck-hands of the steamer Ostrea could also find them.
I have found spat on the shells of the oyster, mussel, clam,
quohog, bar-clam, razor-clam, round whelk and on stones,
but they must occur on many other objects as well. Judg-
ing from the numbers of half-grown oysters that carry
periwinkle-shells at their umbos, it would seem that the
periwinkle is a common base of fixation, although I did
348 THE AMERICAN NATURALIST [ Vou. XLIV
not succeed in finding any with young spat attached.
The dark color of the winkle, of course, makes it easy to
overlook the smallest spat, and besides, these shells are
frequently speckled or spotted with plant colonies such
as Ralfsia verruscosa, the small colonies of which may
simulate young oyster-spat in size, shape and color.
One can distinguish the difference with a lens or by feel-
ing them with a knife-blade. The young of Crepidula
formicata, a low conical-shelled gastropod, is sometimes
more difficult to distinguish, but with a knife-blade one
can slide it along the base of attachment or pry it off and
note that there is no under shell but a broad clinging and
creeping foot. Anomia is one of the closest relatives of
the oyster, but, from its shape and color, is usually not
difficult to distinguish. Upon prying it off, the thin lower
valve of the shell can be seen to have a hole through
which a short stalk of attachment passes and permits
movement. The oyster becomes fixed by means of a se-
cretion, presumably from the edge of the mantle, which
cements the left valve close and fast to the supporting
rock or shell.
The spat caught on glass did not, of course, occur in
regular order of progression in size: the first measured
.87 X 1.03 mm. in height and length, the second 1.58 X
1.20, the third .51 X .55, the fourth .86 X .95. Similarly
the first found on an oyster shell measured 2.4 X 2.3,
while those subsequently procured varied from less than
1 mm. to 6 mm. in height.
The shell of the larva is longer than high, and this is
true not only for each valve but also for the whole shell,
even when the far umbo, through tilting of the shell,
stands up above the near one. The youngest spat agree
also with this statement, but when about 1 mm. in height
the proportions become reversed, and from this time for-
wards the shell grows fastest below and at the postero-
inferior angle. On this account it is more useful at first
to build comparative measurements on the height rather
than on the length—the height, both for the larva and for
No. 522] THE CANADIAN OYSTER 349
the spat, being the vertical measurement from the top of
the umbo to the lowest level of the opposite edge when
the prodissoconch is placed in the position of a creeping
clam.
The spat caught on glass exhibited the characteristic
color of the pelagic larva—the smallest varying towards
pink, the larger towards brown. Those taken on opaque
objects, on the other hand, presented a different appear-
ance—instead of having a pink, reddish or brown colora-
tion as one would expect from comparison with the larva,
or, instead of having a white appearance as might be
looked for by comparison with the older spat and adult
oysters, they preserved a shining, dark, metallic lustre
with a few faint radial lines. In the center of the dorsal
region could be distinctly recognized the larval shell
(prodissoconch) of the oldest free-swimming stage, pre-
senting a uniformity of appearance in all the specimens,
and measuring in the neighborhood of .369 X .384 mm.
in height and length.
The spat-shell (young dissoeconch) is deposited by the
thickened rim of the mantle in layers along the ventral
and terminal edges of the larval valves, but not to any
extent along the dorsal or hinge edge, which explains
the concentric lines below the umbos. The latest de-
posited parts around the margins are very thin and
delicate and exhibit a prismatic structure. At first the
shape varies little from that of the prodissoconch, but
soon the dissoconch becomes extended fore and aft of the
hinge-area in a manner that suggests the wings (ears)
of a scallop-shell, the lower parts preserving a pretty
uniformly curved outline. Later these ale cease to be
conspicuous and the whole outline may become irregular
and variable. Deep or shallow concentric creases pre-
serve more or less indication of stages of growth, and at
places may be portions of radial lines. The deeper con-
cavity of the left valve remains noticeable for a time
after fixation takes place, particularly in sections, but
a little later the lower valve seems to lag behind the
350 THE AMERICAN NATURALIST [ Vou. XLIV
upper one in growth, appearing thinner and flatter, while
the upper one is thicker and more curved. At a still
later period the growing edge of the lower valve becomes
free and the valve again acquires a deeper cavity than
the upper one, preserving this difference throughout life.
While the developing oyster is free to swim or to creep
it is, of course, natural to describe it in terms suitable to
such permanently free-living species as the clam. The
more pointed end, that ordinarily precedes in locomotion
and from which may protrude the velum or the foot, is
the anterior end. The foot is postero-ventral to the
velum. The umbos are postero-dorsal. The hinge is
dorsal, i. e., between and in front of the umbos. The
longest diameter is horizontal, and the height is a vertical
line at right angles to the length. With the growth of
the spat it becomes difficult to retain such ideals as con-
tinuously useful marks of description. At periods vary-
ing somewhat with the individual they become more or
less modified. Preserving the original orientation of
the prodissoconch, the height of the dissoconch soon be-
comes greater than the length, the hinge and umbos come
to mark the narrow anterior end of the spat, and the
larval shell sinks into insignificance. Its left valve fre-
quently becomes obliterated by growth of the surface of
attachment, but its right valve may often be found until
late in the life of the spat, although it is liable to be-
come destroyed by weathering of the umbo-region.
While its position marks the anterior end of the oyster,
it has long since been carried up on the tip of the umbo
of the dissoconch out of reach of the hinge or of the
growing parts, but its anterior end still points in a gen-
eral way in the direction of the anterior end of the adult.
This position and relationship is correlated, as will be
seen later, with the increase of growth of the lower and
posterior parts of the oyster’s body, which occasions
more or less of a rotation round the great adductor mus-
cle, and resulting in longer or rounder forms of shell with
a straighter dorsal and a much curved ventral border.
No. 522] THE CANADIAN OYSTER 351
The right, upper, valve remains flatter and smoother, the
left, lower or attached valve, more deeply hollowed,
rougher, with more conspicuous concentric furrows, and
often with blue tipped projecting processes.
Note on the Asymmetry of the Shell—In the free-swimming larva
the greater convexity of the left valve can not be due to external condi-
tions in the life of the larva since both valves are developed under like
conditions, but must result from a cænogenetie modification of bio-
genesis, which is to say that the difference in the two valves was first
developed after some remote but free and symmetrical ancestors of
the present oyster took to a fixed mode of life, becoming attached by
simply cementing the left valve fast to a solid substance upon which
it rested, and that somewhat later in the phylogenetic development the
hereditary transmission of this character became modified to precede,
in the life of the individual, the conditions which originally ealled it
into existence. It is conceivable that gravity was the prime incentive
both to the occasion for fixation on one side and to the first asymmetry.
Many other mollusks have been similarly modified, e..g., Anomia,
Pecten, Mya, deep-bodied animals that habitually fall over on one side
as soon as locomotion ceases. When once developed there may have
been an advantage in transmitting the lob-sidedness to earlier and
earlier stages in the offspring, which could take place by natural selee-
tion. Such an advantage might well be the determining that the
heavier left side of the larva, when settling to the bottom or when
creeping movement ceases, should promptly come in contact with the
point of fixation and insure the most favourable relative positions for
the activity of other organs whose function had been perfected under
like conditions in the adult. The temporary transfer of the greater
convexity to the upper valve in young stages of the spat can be ex-
plained by the fact that for a time the growth of the lower valve
follows, as it is cemented to, the surface upon which it rests, while the
upper valve is free for growth in every direction. When a sufficient
surface of attachment is secured the edge of the lower valve becomes
free, and then the greater convexity soon reverts to the left valve again.
In living spat the mantle can be often seen protruding
beyond the edge of the shell, but in preserved specimens
it is retracted, sometimes close up to the gills and body,
so that the soft parts of the animal may occupy only a
half to a third of the cavity of the shell. In the youngest
stages the margin of the mantle is thickened, and the
beginnings of tentacular processes are present. Differ-
ences in the two sides afterwards become noticeable, such
352 THE AMERICAN NATURALIST [ Von. XLIV
as thickness, length, and the greater freedom of the right
side from the body, where, for a considerable area in
front of the adductor muscle, there is open communica-
tion from the supra-branchial chamber to the outside at
the dorsal edge of the shell (Figs. 14, 15).
The anterior adductor muscle is present for a time in
the spat, and appears to move upwards and backwards
from its original position in the larva, until it is crowded
to the edge and disappears before the oyster reaches 1
mm. in depth. The posterior adductor muscle, on the
other hand, increases regularly in size and moves down-
wards and slightly backwards, leaving distinct lines on
the shell to indicate its change of position. In spat .86
mm. high it is just below the edge of the prodissoconch
(Fig. 2), in those 1.5 mm. high it is twice the depth of the
prodissoconch from the top of the shell (Fig. 3); in all
stages it is nearly in the median horizontal plane and
slightly posterior to the median frontal plane. The
movement may be effected by a slow creeping of the
muscle, due to downward pressure from the growth of
the body above, or by the addition of new fibers below
and the absorption of old from above, while the impres-
sions on the shell may result from the inability of the
mantle to deposit new layers of pearly matter under the
attached ends of the muscle.
Of the organs enclosed by the mantle a conspicuous
part is early assumed by the gills. The oldest larva or
the youngest spat has two of these—one on each side of
the body, below and between the line of attachment of
the mantle and the base of the foot. At this time each
gill possesses a row of about eight filaments, of which
the anterior are larger and more completely separated
from each other, the posterior are shorter and only partly
separated by vertical creases, while all are united above
by an undivided longitudinal ridge or basal axis that
projects behind and below the mass of the body. At the
time of fixation the right and left gills are approximately
equal, but when the spat reaches .86 mm. in height (Fig.
No. 522 THE CANADIAN OYSTER 353
2) there are about sixteen long filaments on the left side
and about ten short filaments on the right side—the left
gill extending in front of and behind the right one and
occupying most of the gill-chamber (Figs. 4-8). In spat
of 2.5 mm. height there appears on the right side, out-
wards from the already present gill, a third series of
minute, papilla-like filaments (Fig. 14), and when the
spat reaches 3 mm. in height a fourth series is to be seen
in the corresponding position on the left side (Fig. 15).
They increase in size during the growth of the spat
until the animal possesses four complete gill-leaves cor-
responding with those of the adult.
During larval development the gills of the oyster make
but little progress towards the complicated structure of
the adult. The free-swimming animal being small, res-
piration can for a time be partly subserved by its surface.
But fixation effects a marked change in its mode of life
and is followed by far-reaching modifications in its or-
ganization. Rapid increase of size demands improved
facilities for respiration. But, as the animal no longer
comes in contact with its food through swimming move-
ments, it must depend upon the respiratory currents for
bringing food to itself; hence the gills acquire a double
importance. Moreover, since the conditions favorable
to bilateral symmetry are interfered with, the equal
balancing of right and left sides in the further growth
of organs must be left to heredity. At the time of fixa-
tion, as we have seen, the gills are represented by two
bilaterally symmetrical inner gill-leaves. The left (now
under one) grows much faster than the right (now upper
one) so that there is more room and less pressure above,
facilitating the development of the right outer gill-leaf
before the corresponding one of the left side. Irregu-
larity also soon becomes noticeable in the higher level
of origin of those of the right side and in a tendency
towards a radial symmetry of the organs with reference
to the posterior adductor muscle.
A study of sections of larve and young spat reveals
354 THE AMERICAN NATURALIST [Von XLIV
a remarkable difference in the apparent ontogenetic de-
velopment of the gills of the oyster as compared with the
recorded phylogenetic development in lamellibranchs.
This, like the larval asymmetry of the shell, may be un-
derstood as a short-cut towards the final structure. As
the first-formed, short, basal axes grow backwards they
carry with them a continuation of the body-wall, con-
necting them with one another across the median sagittal
plane and with the mantle at both sides, giving rise to
a very imperfect separation into branchial and supra-
branchial (or cloacal) chambers. The filaments are at
first short, solid, papilla-like outgrowths from the axes
—the older and larger anterior, the younger and smaller
posterior. They originate behind, but by formation and
growth of new ones those first formed become pushed
forwards. The at first small and shallow supra-branchial
chamber follows this movement and penetrates each fila-
ment from above, distending it laterally but not antero-
posteriorly because of the pressure of contiguous fila-
ments. This process continues until each filament is
severed into an outer and an inner section, the inter-
mediate portion becoming constricted through, but never
completely at the tip. In this manner each gill-leaf be-
comes split into outer and inner lamelle of similar struc-
ture, but the one the reverse of the other, with its parallel
half-filaments and intervening slits overhung by cilia.
Imperfect separation of the transverse median portions
of the opposed halves of some filaments gives rise to the
inter-lamellar junctions, while the imperfect separation
of the opposed sides of different but contiguous filaments
oceasions the inter-filamentar junctions. The same proc-
ess can be observed later in the development of the right
and left outer gill-leaves as well as in the terminal fila-
ments of any one of the four (Fig. 14).
For a long time it has been customary among zoologists to speak as if
the oyster, or other bivalve mollusk, possesses four gills, which it really
appears to do, two on each side of the body. Comparative study of the
anatomy and of the development of different groups has ied to the
No. 522] THE CANADIAN OYSTER 355
view that bivalves have been developed from primitive, symmetrical,
gastropod-like ancestors, with a simple head in front bearing two
tentacles, two eyes, and mouth with a rasping tongue; a low conical shell
above that could be drawn down over all the soft parts and lined by
a mantle that secretes its material; a flat creeping and clinging foot
below; and two feather-shaped gills, disposed right and left, projecting
backwards. Each of these was a symmetrically constructed, bipectinate
gill or ctenidium, having a central axis with two rows of filaments, an
upper and a lower. There are still living limpet-like gastropods along
our coasts possessing such characters, although no one species retains
them all or in the most primitive form.
The group of mollusca to which the oyster belongs has in the course
of time suffered modifications of the characters mentioned. Its mem-
bers have taken to a more quiescent mode of life, such as burrowing in
sand or fixing to rocks, and in consequence have largely lost those ex-
ternal organs of locomotion, plunder and special sense so necessary to
free-roving animals. The absence of a head has been regarded as char-
acteristic (hence the group has been called Acephala); in place of a
single piece they have developed a shell with two valves (Bivalva) ; the
foot in by far the greatest number of forms has become somewhat
hatchet-shaped (Pelecypoda); the gills are leaf-like, each separable
into flat plates (Lamellibranchia). If all bivalves had become equally
modified it would certainly have been difficult to determine the origin
of the group, but, owing to the diversity of natural conditions and
the reactions of these upon living organisms, certain species have been
forced to pursue special lines of action in order to better their chances
for life, with the result that the organs chiefly concerned have become
more specialized, while other organs have retained much of their original
structure, and it is just these organs that are especially valuable in
tracing ancestral affinities. As long ago as 1848 Leuckart (16) com-
prehended the essential unity of molluscan gills, and his views have
been supported by Menegaux, Pelseneer, and many others. Peck has
studied the Lamellibranch gill. Lankester, Hatschek, Thiele, Lang,
are among those who have studied the phylogeny.
In the oyster larva one can at once recognize the ctenidial axis with
its lower series of filaments, but one has to await the spat of 2.5 to
3 mm. before he can see the upper series, which has had to rotate out-
wards nearly half way round the axis in order to remain accommodated
in the branchial chamber. In the adult there is but one gill on each
side, comparable with a gastropod ctenidium and composed of two
hemibranehs (gill-leaves or branchial folie); each hemibranch may
be split lengthwise, from above nearly to the lower free edge but not
through it, into outer and inner plates (lamelle), or subdivided trans-
versely into numerous V-shaped branchial filaments of which one half
356 THE AMERICAN NATURALIST [Vou. XLIV
belongs to the outer lamella and the other half to the inner lamella of
a hemibranch.
In the course of phylogenetic development the originally straight
filaments have become bent upon themselves to permit of greater length
(surface) and still be protected within the branchial chamber—those
of the ventral series were folded inwards and those of the dorsal (but
now lateral) series were folded outwards, while the tips coming in con-
tact with the foot in the one case or the mantle in the other clung for
support, were directed upwards, and finally became fixed along the side
of the body or along the inner surface of the mantle. At places their
ciliated surfaces became knit together for further support, leaving
intervening gill-slits between contiguous filaments, and ascending water-
tubes between opposite lamelle. At the level of union of the gills
with the body and with the mantle there is separated off a branchial
chamber below from a supra-branchial (or cloacal) chamber above, and
by the activity of the cilia water is brought into the former, directed
through the gill slits, up the water-tubes, and out by the cloacal cham-
ber. The original ctenidial axis lies above the base of origin of each
pair of hemibranchs, and is marked by retaining its connection with
the body by a septum carrying blood vessels and nerves (Fig.
Two larval organs soon disappear under the new con-
ditions brought about by fixation: the velum and the foot.
Even in certain old, free-swimming larve, that are per-
haps belated in their efforts to become attached, a re-
duction in the size and vigor of the velum is noticeable.
This would seem to suggest an atrophy of the organ,
which might be followed by either dehiscence or absorp-
ion. I have occasionally seen old larve with the velum
protruded and partly severed from the body, as well as
completely separated vela still capable of muscular and
ciliary movements. Such cases may have resulted from
accidental pinching off by a snapping closure of the
shell-valves. But the size, appearance, enfeebled move-
ments, and even the accident itself, pointed towards an
antecedent loss of ability to respond correlatively to the
activity of neighboring organs.
Balfour (21, p. 215) states: “ It has been suggested by Lovén, though
without any direct evidence, that the labial tentacles of adult Lamelli-
branchiata are the remains of the velum. e velar area is in any
ease the only representative of the head.” :
Ryder (31, p. 404) says: “The detachment of the ring or crown
No. 522] THE CANADIAN OYSTER 357
of vibratory filaments or cilia from the embryo as asserted by Davaine
as not been confirmed by any other observer” and in 8, p. 790:
“ Davaine makes the statement that the velum appears to drop off
sometime about the end of the larval period. Gerbe, on the other hand,
asserts that the velum is transformed into the palps.’ his is a fasci-
nating view of the destiny of the velum: that it does not become entirely
useless and completely disappear, that its main line of folding in the
median sagittal plane represents the division into two halves which
bend around the sides of the mouth, each half again folding to form
the two palps, while secondary radial foldings may give rise to the fur-
rows and ridges and the cilia become redistributed. On the other hand
it is not easy to see exactly how an organ of the size and shape of
the velum could become reduced, remodelled, changed in position and
folded in such a way as to form an anterior pair of palps, connected
across in front of the mouth, and a posterior pair, connected behind
the mouth and underlying the first, while the two on one side are
attached along a line running back from the mouth and have their
original ciliated surfaces turned towards each other. Moreover, this
would mean a much more intimate connection between the epithelium
of the velum and the inner walls of the mouth than exists in the larva,
where the mouth-opening is surrounded by a funnel-shaped projecting
rim, that is separated from the velum in front by a crease, while the
lower lip is free to a still greater extent. There is no observable con-
nection between the arrangement of cilia on the velum and on the
palps, nor any positive antecedents of the furrows and ridges of the
palps on the velum. esides, from a consideration of the size of the
velum in the larva and the size of the smallest recognizable palps in the
spat, it would appear that the velum would have to suffer a period
of decay followed by a period of vigorous growth. Restricting one’s
observations to the oyster it might seem just as likely that the lower
palps should originate from the foot and only the upper ones from the
velum. The foot is ciliated and has a median ventral furrow corre-
sponding with the division-line between the lower palps. In that case
one would expect to find vestiges of pedal organs, such as pedal ganglia
and otoeysts, about the bases of these palps under the esophagus, as
well as supra-w@sophageal ganglia in the bases of the upper palps in
front of the esophagus. But in my sections I have not been able
to recognize these structures, and reflection on other bivalves, where
both foot and palps persist as functional organs in the adults, proves
beyond doubt that the foot has nothing to do with the lower palps. I
have three series of young spat-oysters with the shell measuring rather
less than 1 mm. in height, and from a study of them I should say that
the palps originate from, and belong to, the walls of the mouth, i. e.,
are extended upper and lower lips.
358 THE AMERICAN NATURALIST [ Vou. XLIV
The foot, after fixation of the larva, no doubt ceases
to grow, perhaps becomes reduced, but in any case
shrinks against, is absorbed into and incorporated with
the anterior ventral wall of the rapidly enlarging ab-
domen. In 1 mm. spat it is scarcely recognizable as a
median, grooved, muscular thickening between the lower
lip and the first gill-filaments.
Jackson (12, p. 303): “ The fact that a velum, or swimming organ,
exists up to the period of permanent fixation accounts for the great
reduction of the foot, because that organ is unnecessary while the
animal is provided with another locomotive organ, and is useless for
progression after the animal is attached. he reduction of the foot
is eae papagen to disuse and a high degree of concentration of
developm . seen so markedly in the development of the oyster.”
I have y shown, _ dealing with the foot of the larva, that the
part designated “foot” by Jackson and others is not the real foot,
which is only to be nee at a very much later period and which they
had not recognized.
The intestinal system has all its parts represented in
the larva. With the growth of the spat these suffer cer-
tain alterations in relative sizes, shapes, and positions.
Perhaps the most radical change is produced by a rota-
tion of the body in such a way that the mouth moves for-
wards and upwards towards the antero-dorsal margin
of the prodissoconch. This doubtless accompanies and
is associated with the loss of the velum, which in the
larva is so large as to occupy all the fore part of the
cavity of the shell, forcing the mouth and cesophagus
backwards to near the median frontal plane of the body.
In spat under 1 mm. in height when the velum is com-
pletely cleared away, the mouth can occupy its normal
position as in the adult. Such a rotation may appear
at first thought inexplicable, but when it is remembered
that in the prodissoconch the body of the larva is pos-
sessed of great freedom of movement, being at times
thrust far forwards, putting the retractor muscles on the
stretch, it can be readily understood. In fact it is con-
ceivable that these muscles may be made to do duty in
producing the rotation and in fixing the body in its new
No. 522] THE CANADIAN OYSTER 359
position, for after the loss of velum and foot there is no
longer any need of such free movement, consequently
these muscles may lag behind other parts in growth, ex-
erting a tension as they do so sufficient to cause the rota-
tion. In harmony with this view is the similar upward.
movement of the anterior adductor muscle and the rapid
downward movement of the posterior adductor muscle.
In 1 mm. spat the two sides of the mantle, meeting
above at a broad angle, appear to be suddenly thickened
(Fig. 4) into a sort of upper lip for the widely open,
transversely crescentic mouth, that opens a little farther
back on the right side than on the left. The anterior
end of the body, between the first gill filaments, serves
as lower lip, while very short upper and lower palps,
possessing only a couple of ridges and furrows, are con-
tinuous with the lateral margins of the upper and lower
lips, and project on each side of the anterior end of the
median left gill. In 2 mm. spat (Fig. 13) the palps have
increased perceptibly, doubled the number of furrows,
turned down, and are seen to be anterior to, but not con-
tinuous with, the gills. Judging from the great progress
made between these two sizes, I believe that the palps
originate sometime before the spat reaches 1 mm. in
height, but are not present as such in the larva, where
upper and lower lips and palps are represented by the
internally-ciliated, funnel-like, projecting rim of the
mouth. When this rotates upwards it comes to lie be-
tween the mantle above and the forward growth of the
abdomen below, while its side-angles fold outwards and
backwards becoming the palps, their like surfaces turned
towards each other and their cilia continuous with that
of the mouth and esophagus. Later they become ad-
herent to a greater extent along the lateral walls of the
anterior part of the enlarging abdomen, and direct food
from the gills into the mouth.
Rice (33, p. 28) curiously made the observation: “ During the first
period of attachment when the shell itself is not firmly attached, but
simply held firmly down to the substance with which it is in contact,
360 THE AMERICAN NATURALIST [Vou. XLIV
the young animal gets its food, or a portion of it, by means of a sort
of proboscis, or elongation of the mouth part, which is capable of being
moved about freely within the shell cavity. This proboscis stage lasts
until the gills are fully formed and becomes of sufficient size to supply
food to the animal, when the proboscis, or rather its flexible end, is
_transformed into the labial palps which become closely connected with
the gill-leaves.”
The mouth narrows down into an cesophageal tube of
transversely elliptical calibre, lined by cells similar to
those of the mouth. It is still relatively long and curves
over the anterior end of the stomach, passes between the
lateral origins of the liver, and enters the stomach from
above (Figs. 2-10). The stomach is a relatively large
mass of irregular shape and large cavity, occupying a
good part of the space in the prodissoconch. There may
be considered to be three prominent extensions: one for-
wards below the cesophagus, another postero-dorsal be-
hind the entrance of the cesophagus, and a third, begin-
ning as a compressed ventral extension of the first, slants
downwards and backwards towards the adductor muscle,
becoming broad, deep, regular and thick-walled. This,
I am satisfied, is the portion that secretes the crystalline
style, and originates postero-dorsally in the left umbo
of the larva, but becomes moved to its present position
during the rotation of the viscera, and presents the ap-
pearance of being internally ciliated. Just in front of
the insertion of the esophagus but on each side of it,
i. e., dorso-laterally, spring the stalks of the liver—one
on the left and two on the right. These branch into
numerous follicles lying on both sides of and above the
stomach and projecting far forwards to the region of the
mouth. On the ventral aspect of the stomach, in the
same region, springs the intestine, on the right, in the
crease between the compressed antero-ventral extension
to the left and the main central body of the stomach
above (Fig. 9). From this the intestine passes back-
wards on the right, then upwards behind the rounded
postero-dorsal extension, forwards and down the left
side, where, near the anterior end of the stomach it turns
No. 522] THE CANADIAN OYSTER 361
backwards and then down, finally passing towards the
median plane to the anal opening over the adductor mus-
cle. The stomach sometimes contains diatoms and
desmid-like clusters of one to four nucleated cells.
The nervous, circulatory, excretory and reproductive
systems remain undescribed, and shall not be treated of
in this paper; they bear less important relations to those
characters of external morphology and gross anatomy
that are so useful as marks of recognition and description.
The first, second and third spat oysters caught on glass
were of different sizes and were consequently devoted to
morphology, but the fourth, being of approximately the
same size as the first,.was used for a physiological ex-
periment in growth. This spat was procured on the
afternoon of August 31 at Ram Island, about six miles
from the station, and measured at 5 p.m. .861 X .953 mm.
in height and length and had about sixteen gill filaments.
It was kept under the bridge of Keir’s wharf until the
afternoon of September 1 and measured again, but it
showed no increase of size. It was then taken to Ram
Island and placed under its original conditions in a
crock, and at 4 p.m., September 7, it measured 1.276 X
1.261 mm. and had about twenty-four gill filaments. It
was kept in running seawater until 5 p.m. of the eighth
and then put under the bridge of the wharf until the
morning of the ninth, when it was again taken to Ram
Island. It did not grow either in the running water or
under the bridge where there is at times considerable
tidal current. On the forenoon of the sixteenth it was
again brought in and measured 1.753 X 1.661 mm. From
these observations it would appear that the young spat
did not become immediately accommodated to new condi-
tions after being disturbed, that during a period of six
days of undisturbed growth it increased to one and one
half times its original height, and that at the end of seven
days more it had grown to twice its original height. One
might say that it doubled its height and length in two
weeks.
362 THE AMERICAN NATURALIST [Vou. XLIV
Having to leave for Montreal by the twentieth, it ap-
peared that the best thing left for me to do was to plan
an experiment for the winter. I had three strong wire
baskets made—two feet square by three inches deep and
lids to fasten over—in which I placed perhaps three to
four hundred small, selected, living oysters having one
or more minute dark spat upon each shell, surrounded
with cireular lead-pencil marks for convenience in rec-
ognition. These baskets were connected by a long rope
and put down in a deep channel between Hog and Bird
Islands, presumably out of the way of fishermen, ice-
shoves, ete. I expected the small dark spat, which varied
from 1 to 4 mm. in height, to grow to about the size of
one’s thumb-nail during the winter and spring, as this
was the size of the smallest white spat I recollected hav-
ing seen upon first arriving at Malpeque the previous
spring. The first thing I did the succeeding spring was
to go and grapple for these baskets, but despite every
effort they could not be found. The marks of the rope
and baskets could be observed on the bottom, and the
suspicion was near that some curious fisherman, in set-
ting lobster traps in the early spring, had found them
and taken possession for the rope—an illustration of the
immediate short-sighted petty-selfishness and improvi-
dent disregard of ee wholesale benefits of many
fishermen.
The next thing that suggested itself was to look for
spat of the previous autumn on the shells where I col-
lected those for the preceding experiment, and I was
surprised to find dark spat still there, that had appar-
ently not grown a bit or changed in color during the
winter. There were fewer of them—many having died
and lost the upper valve or even both valves were gone,
leaving sometimes a patch or rim to indicate where a
spat had been attached. The largest dark spat collected
the previous autumn measured 6 mm., and the largest
found the next spring was 8 mm. in height. They re-
tained their dark metallic luster with radiating ridges
No. 522] THE CANADIAN OYSTER 363
or lines and very thin edges—the whole oyster being thin
and fitting so solidly against the supporting shell as to
require some force with a knife-blade to separate it. In
some of the larger was to be seen a tendency to turn
white, in that the dark rays were irregularly separated
by reversed lighter radiations. Sizes but little larger
than these may be found later in the spring and in the
early summer. The spat of the oyster-fishermen, varying
mostly over one inch in length, are abundant, many bar-
rels of which are collected by the Indians at Ram Island
Point and thrown out off Lennox Island, the Indian
reserve, for further growth.
Important results added to those given in the preced-
ing part on the larva are:
19. First systematic use of plankton nets in the pro-
curing of oyster larve.
20. First undoubted recognition of the larva of the
oyster in Canada.
21. Stages hitherto unobserved (constituting the blank
referred to by Jackson) may be taken in the plankton net.
22. The first undoubted recognition of young stages
of Canadian oyster spat.
23. The spatting period has been limited.
24. The free-swimming period of life of the larva has
been limited.
25. Size is a more useful criterion than age.
26. Sections have been prepared of both larve and
spat in order to determine accuracy of structure.
27. The gills have been carefully studied.
28. The intestinal system has been described through-
out. |
29. Development has been followed up to adult sizes.
30. Many structural or other observations have been
made, which to enumerate would be largely to rewrite
foregoing pages.
41.
THE AMERICAN NATURALIST [ Vou. XLIV
ADDITIONAL SELECTED LITERATURE
1848. Leuckart. Ueber die Morphologie und Verwandtschaftsverhalt-
nisse der Wirbellosen Thiere. Braunschweig.
1849. Lovén. Arch. f. Naturg. (and Ann. Mag. Nat. His., 1856).
1853. Davaine. Comp. Rend. et Mém. de la Soc. de Biol. Paris, IV,
5-339.
1876. Gerbe. Zool. Record, XII, Mol
1877. Peck. The tani of the 1 ST Gill. Quar. Jour.
Micros. Sci., XVII, pp. 46-66.
1880. Balfour. A Tre atise on saa Embryology, p. 215.
1883. Lankester. Encycl. Brit. apo Mollusea).
saith Hatschek. Lehrbuch der Zoologie
888-89. Menegaux. r la branchie chez tói Lamellibranches. Bull.
Soc. Philom gi
1889. Pelseneer. Sur la ae phylog. dai Pélécypodes. Bull. Soc.
France et Belgique. Contrib. à 1’étude des Lamell. Arch.
, 1891.
1891. Thiele.” Die Stammesverwandtschaft der Mollusken. Jena.
Zei aturg.
1896. Lang. Text- book of Comparative Anatomy, II.
1900. Korschelt and Heider. Text-book of Embryology of Inverte-
es,
1878. Winslow. Extracts from Report of Investigations of the Oyster
Beds in Tangier and Pokamoke Sounds and Parts of Chesa-
peake Bay.
1884. Winslow. Bull. U. S. Fish Com., = 234, 468-9.
1882. Ryder. Bull. U. S. Fish Com., pp. 4 “dg 9.
1883. Ryder. Bull. U. S. Fish n Calis pp.
1883. Rice. Experiments in Over Lae Forest and Stream,
N. Y., Aug. 9, XXI, pp. 28-29.
1885. Rice. The Prop. and Nat. His. of the Amer. Oyster. Rep.
Com. Fish. State of New York. on pp. 71-137.
1880. Brooks. Proc. Bos. Soe Ds
1905. Brooks. The Oyster. Balttinote: pp. 12 25.
1890. Jackson. Studies of Pelecypoda. Amer. Nat., XXV, pp. 1132-
oO
142.
1891. Ji espe The Mechanical Origin of Structure in Pelecypoda.
r. Nat., pp. 11-21.
OE I ‘Neleon, Reports of the Biol. Dept. of the New Jersey
A Coll. Pi r. Sta.
gric.
1874. Whiteaves. Notes S os Marine phen ete. Appen. U,
pp- 29. 6th Puc Rep. Dept. Mar. and Fish., Ottawa.
1889. Ganong. Economic Mollusea of Aca
1899. Kemp. Report on Can. Oys. Fish a Oys. a 31st Ann.
Rep. Dept. Mar. eat Fish., Oia pp. 359.
BRIEF NOTES AND EXTRACTS
Ryder (I. The Larva. Literature, No. 6, f. 3) and Jackson (No. 12,
E
2, 17, 18) have given figures of the youngest stages of oyster spat.
No. 522] THE CANADIAN OYSTER 365
In the cca from the literature of any figures of the oldest free-swim-
ming larve, I have already referred to these and for a more satisfactory
understanding reduced their measurements to actual sizes. They represent
the spat within 24 hours aftar fixation an measure in the AR of
3 mm. in height. Ryder’s Figs. 5, 4, 6, 7, represent spat of about .34, .
51, .54 mm. height. Jackson’s Fig. 3 was perhaps about .55 mm ots and
his Figs. 20, 21, about .91 mm. high. Then come Ryder’s Fig. 8, about
1.6 mm., his (No. 8, p. 784) Fig. 2 of 3 mm., and Jackson’s Fig. 4 of 5 mm.
My Gco spat were .51 and .86 mm. high and from 1 mm. upwards I
had such abundance I could select whatever sizes I desired.
acco ie recorded differences between European and American
ieee. it is not always safe for us to judge from analogies. On the other
hand, except ae local differences of temperature, food, fauna, ete., the
wae iter of oysters in the United States is wy immense value to
= ada,
Importance of Embryological Study— Winslow (No. 30, p. 234): “I
would press the importance of continued investigation of the embryological
Knowledge of these influences and prp Baoa of their effects
are absolutely necessary to the success of oy Thousands of dol
lars would be annually saved to the SE eE u they ¢ ould
determine, with even approximate accuracy, the date when the uated
ur.
spawning season. Careful, continuous, and ela te study and investiga-
tion alone can determine these points and others of equal importance. Con-
sidering the value of successful determination, not only in a scientific
but sonore no ers or ear should be spared to obtain it.’’
Spawning.—Winslow (29, p. 130), Tangier and Pokamoke Sounds:
‘‘The spawning season was said to be from May until August inclusive,
though most of the spawning was done in June and July.’’ Brooks (5,
p. 10): ‘‘Oysters in from 1 to 6 feet of water in the vicinity of Crisfield,
probably spawn between the middle and end of May, but oysters with ripe
thirtieth ” ia although most of them spawn late in June.’’ Ryder (7,
p. 326): n the region of the Chesapeake the most important spawning
period seems to extend over the months of June and July, but —_
ripe spawn may be found even much earlier and later than this.
Growth of Larva.—Ryder (7, p. 328): ‘‘At a temperature of 75 to
eri o; i to
yet been certainly determined . . . it has been found by the ena that
in 24 hours after fertili ization : as represented at m in Fig. 1. The young,
aveni after attachment, continue to w as larve ... when the valves
of the fry have acquired umbos the Sentai of the spat shell begins.’’
Ryder (9, p. 728): ‘‘I would infer from what we learn from the study of
other animals that it may require quite a week before an embryo reaches
366 THE AMERICAN NATURALIST - [Vou XLIV
the dimensions of 1/80 um an inch, but we have no data upon which to base
any conclusions of value
Spatting.—Rice (34, p. 115): ‘‘ The attachment takes place in about
two days from the time of fertilization.’’ Jackson (11, p. 532): ‘‘One
of the most successful spatting grounds at Buzzards Bay is a sand spit on
South Wareham .. . oysters were spatting most abundantly late in July
and early August.’’
Growth of Spat.—Ryder (9, p. 728): ‘‘ After fixation the growth of
spat is very rapid—week or 10 dys., + inch across; 20 dys., 7% in.; 44 dys.,
3% in; 48 dys; 1 in.; 79 dyb 12 in.; 82 dys, 2 in.’’ Ryder (7, p. 328),
Figs. 5, 6, 7, et
Number of p .—Ryder (32, p. 287): ‘‘As many as 25 young oysters
might have been counted on a surface of one square inch’’ on wooden buoys
taken up early in July near keyp Holl. ‘‘More than 100 oysters on a
single shell.’”? Rice (34, pl. 6, f. 12) figures the inside of an old oyster
valve with 165 young attashed. a never saw anything like such numbers
at Lor ie: to examine many shells to find one bearing one or
two spat
Daa .—Winslow (30, p. 233) gives for the United States 22,195,370
bushels, of which 19,712,320 bushels came from Chesapeake and Delaware
Pays. Kemp (42, p. 353) gives for Canada a table from Hine it is seen
the maximum production was reached in 1882 of 64,646 barr
Breeding.—Rice (34, p. 115): ‘‘Thẹ first efforts in this ae in the
direction of artificial EE I were made by the writer in the summer
nating the eggs and in raising the embryos until they were six days old.’’
Brooks (5, p. 3): ‘f. . . succeeded in meng countless millions of young
sters.’ ?
Oyster Culture.—Under this head might be n an extensive litera-
ture dealing largely with the transplanting of oyster spat, that have escaped
the accidents of nature, to more favorable leait a as regards crowding,
competition, food, cleanliness, ete.; but also to a more limited extent the
breeding of larv ysters under artificial conditions that protect them
against extremes of temperature, violent storms, starvation, rapacity of
animals, ete., and the furnishing of abundant and suitable objects for
m The subject is too vast for discussion in this place.
would appear that, to some extent simulating the life-history of the
: ies the short period of activity in investigation and experimentation
initiated by Brooks was succeeded by a period of quiescence in research,
d t mined anew. iber
taking, self-reliant, and unbiased work, like that of Nelson (37), may do
much to originate a new cycle of exact observation, whieh sooner or later
may be turned to account in a rational system of oyster culture.
MONTREAL, May 18, 1909.
THE ALIMENTARY CANAL OF A CARBONIFER-
OUS SALAMANDER
DR. ROY L. MOODIE
THE UNIVERSITY OF KANSAS
Investigators, during the progress of their research
into the anatomy of extinct animals, have the good for-
tune, from time to time, to be able to add items of inter-
est to the soft anatomy of the forms which they are
studying. In the nature of the case the soft parts are
very rarely preserved and when they are represented it
is usually an imperfect record. Occasionally, however,
the rocks yield forms which afford very complete knowl-
edge of the soft anatomy of the animal. This has been
strikingly shown in Dr. Dean’s studies on the fossil
sharks of the Cleveland shales of Ohio. Dr. Eastman
and Dr. Parker have also studied and described the soft
parts of the head, especially, of a peculiar little fish from
the Waverly shales of Kentucky which Dr. Eastman has
named Rhadinichthys deani. In this species, which is
represented by an abundance of material, there are
clearly preserved the various portions of the internal
ear, the outlines of the lobes of the brain and traces of
an arterial blood vessel with some of its branches. There
are many other instances in which the soft anatomy of
fossil fishes has been developed. Many of these are
given more at length by the-writer in another place.
Among the higher vertebrates the softer structures
are not so well known. The outlines of various branchio-
saurians are known from the studies of Fritsch, Credner,
von Ammon, von Meyer and Thevenin, who have de-
scribed these forms from the Permian and Carboniferous
of France, Bohemia and Germany. Cope has dwelt at
some length upon the preservation of the shape and
some of the coloring matter of the eye of the reptile-
367
368 THE AMERICAN NATURALIST [Von. XLIV
like microsaurian, Amphibamus grandiceps, from the
Mazon Creek shales of Illinois. The writer has been for-
tunate in observing the outline of the body of this
species. He has also observed muscle fibers in the ab-
dominal wall and the outline of the body in Tuditanus
walcotti from the Coal Measures of Ohio. He has de-
scribed, also, the fin membranes, the lateral line organs,
the form of the body and the ‘‘pigmentum nigrum”’ of
the eye of Micrerpeton caudatum from the Mazon Creek
shales. Dollo has described an unusual amphibian from
the Wealden of Bernissart, Belgium, Hyleobatrachus
croyui, which showed the preservation of some of the
body membranes and thus a portion of the form of the
body. Numerous observers have written on the form of
the feet in amphibia as they have been recorded by their
footprints in the rocks.
Nothing has ever been contributed to the structure of
the intestinal tract of the fossil amphibia, and from the
nature of the case as well as from the extreme rarity of
approximately complete specimens of these animals it
would be an unexpected event if such were discovered.
Our confidence in the preserving powers of the rocks
grows, however, from year to year, and if we look long
enough we can not fail to uncover many things of in-
terest. ;
The amphibia of the Mazon Creek shales have always
been noted for the unusual perfection of their preserva-
tion, which they have shared with other animals and with
the plants from that historic locality. Amphibamus
grandiceps, the first amphibian described from these
shales, was made known in 1865 by Professor Cope from
an almost perfect specimen. The next species made
known from these shales was the form described in 1909
by the writer under the name Micrerpeton caudatum.
It was based on a specimen which lacked only portions
of the limbs of being complete. Nothing of the intestinal
tract was observed in either of these species. It was
somewhat surprising, on that account, to observe among
No. 522] A CARBONIFEROUS SALAMANDER 369
a lot of specimens loaned the writer for study by Yale
Museum, on two excellently preserved examples of the
Branchiosauria, apparently adult, molds and impressions
of what appeared at first sight to be intestines. Further
study showed that in the smaller specimen there was
preserved the entire alimentary canal and the other
specimen had the alimentary tract approximately com-
plete. There are no traces of branchiz to be observed in
either specimen.
= The species which these forms represent is unknown
and the writer has accordingly proposed for them, in
another place, the name Ewmicrerpeton parvum, new
genus and species, and has regarded them as representa-
tives of the family Branchiosauride. The smaller speci-
men has the more completely preserved canal of the two
and the description given below will apply mainly to that
specimen.
The nodule which contains this interesting little fossil
measures two and a quarter inches by two inches and the
fossil salamander occurs as nearly as possible in the
center of the nodule (Fig. 4). The white kaolin which
has usually replaced the bones in the Mazon Creek fossils
has nearly all become eroded, only that of the right hu-
merus remaining. The animal is of course preserved on
its back.
If it were not for the fact that the esophagus became
loosened and dropped down from its place shortly after
death, the alimentary canal would be in place and would
immediately recall a freshly dissected specimen of a
recent salamander. The anterior end of the esophagus
lies obliquely across the chest region with its tip pointing
slightly downward. The length of the esophagus proper
is only about three millimeters. The entire animal meas-
ures but thirty millimeters in full length from the snout
to the tip of the tail, the form of which is clearly pre-
served (Fig. 1).
The cesophagus, as it is preserved, lies in a semi-sig-
moid curve with the convexity anterior. It enters the
370 THE AMERICAN NATURALIST [Vou. XLIV
cardiac portion of the stomach by a gradual constriction.
The stomach is clearly preserved as a distinct sac-like
organ with two lobes which correspond to the cardiac and
pyloric limbs. -The stomach measures about seven milli-
meters in length by two millimeters in its greatest diam-
FIG. An enlarged photograph of the smaller specimen of cr umicrerpeton
parvum Praline nearly the complete course of the intestine.
eter. The muscular constriction which divides the organ
into pyloric and cardiac divisions occurs at a distance of
four millimeters from the upper end. The pyloris is
designated by a rather pronounced constriction which
may be partly accidental although it recalls the pyloris
of the frogs very strongly. From this constriction, which
lies on the left side of the fossil, as it is preserved, the
duodenal portion of the intestine makes a straight course
posteriorly to near the anal region, where it takes a sharp
bend and curves back to run parallel with itself for the
No. 522 A CARBONIFEROUS SALAMANDER Bye!
distance of four millimeters. In its upward course, im-
mediately on leaving the anal region, the intestine en-
larges and practically the same enlargement continues
throughout the remainder of its course to the anus. At
the distance of a millimeter from the anal end the rectum
dilates probably an eighth of a millimeter to form the
Fic An enlarged photograph of the larger specimen of O
parvum show! ing portions of the impressions of the alimentary cana
cloaca. After the intestine has continued its parallel
course for the four millimeters as stated above, it turns
abruptly to the right for a distance of two millimeters.
It then runs posteriorly for a short distance, then bends
back and under itself to again make a double sigmoid
curve, when at a distance of six millimeters from the anus
it assumes a straight course which it continues to the end
Fig. 3).
The anus lies at a level which is approximately that
372 THE AMERICAN NATURALIST [ Vou. XLIV
of the lower end of the femur, which is preserved as an
impression on the left side of the fossil, thus agreeing
in its position with that found in the modern Caudata.
Lying inside of the curve of the stomach and partly in-
closed by the cesophagus is a smooth area which may
Fic. 3. A drawing of the smaller specimen of Eumicrerpeton parvum
pea the full course and condition of the intestinal tract. x2. o, œsopha-
liver; 8, stomach; d, pyloris; i, small intes stine; a, anus. Portions of
the feds bones are also outlined as well as the anterior end of the interclayicle.
possibly represent the impression of some of the acces-
sory digestive glands such as the liver. Occurring in
this smooth area are numerous fine lines which possibly
represent blood vessels; but they are so imperfectly pre-
served that I will not be sure.
No. 522] A CARBONIFEROUS SALAMANDER 373
The other and larger specimen (Fig. 2) is some ten
millimeters longer than the example described above.
The alimentary canal is represented not as a mold, as in
the specimen described above, but by an impression from
which the mold has been lost. By taking a wax impres-
sion of this specimen the form of the cesophagus, stomach
and portions of the intestines, with the same form and
arrangement as has been described, are beautifully
shown. The esophagus has also in this specimen been
loosened and dropped down. The anus is quite prom-
Fic. 4. The nodule containing the smaller fossil shown natural size.
inent and lies somewhat beyond the base of the tail.
The tail is preserved entire in an elongate V. On its
membranes are to be seen very clearly preserved the
median and dorsal lateral lines which have been so com-
pletely described for Micrerpeton caudatum. Lying be-
side the anus in both specimens is a small elevation
which may in both cases be accidental or it may repre-
sent either the posterior end of an oviduct or some anal
gland which the branchiosaurians possessed.
374 THE AMERICAN NATURALIST [Vou XLIV
The modern amphibia present many problems for
consideration. Among the most interesting of these is
the one which is concerned with the phylogeny of the
living forms. An attempt has previously been made
by the writer! to elucidate the problem of descent so far
as the Caudata are concerned. The present contribution
is a further extension of that effort and it supports the
conclusions there drawn.
Representatives of several genera of the modern
Caudata have been dissected in order to make a direct
comparison of the fossil alimentary canal with that of
the recent forms. Among the forms dissected may be
mentioned Ambystoma tigrinum, Ambystoma opacum,
Diemyctylus torosus, Diemyctylus viridescens, Desmog-
nathus fuscus Raf., Spelerpes bilineatus Green, ete. In
some cases representatives of several stages in the growth
of the individual species have been available for study.
The alimentary tract of Desmognathus fuscus Raf. from
the vicinity of Ithaca, New York, resembles in a marked
degree that of the fossil form. The nearest approach to
the condition there represented is, however, found in an
immature branchiate individual of some 47 millimeters
in length, of Diemyctylus torosus Esch., from a fresh-
water pond on Orcas Island in Puget Sound. The pres-
ence of this species on the island is very suggestive and
its bearing on the geological age of the caudate amphibia
will be given elsewhere. It is of extreme interest that
the condition represented by the fossil should resemble
so closely that of an immature rather than a mature
form since it lends support to: the recapitulation theory.
Perhaps the representative species of the genera Des-
mognathus, Spelerpes, Hemidactylus, ete., are forms
which have become restricted in their development and
thus represent more nearly in the structure of their ali-
mentary canal the ancestral condition, as is also the case
in the immature form of the Diemyctylus torosus Esch.
The writer has attempted to show that the modern
* AMERICAN NATURALIST, XLII, No. 498, June, 1908.
No. 522] A CARBONIFEROUS SALAMANDER 375
Caudata are forms which have evolved by a process of
degenerative evolution and he has supported his con-
tention by a direct comparison of the skeletal anatomy
of the Branchiosauria and the Caudata. So far as the
skeleton is concerned the caudate organization is less
high than that of the Branchiosauria. Such can not be
said of the alimentary canal, for it at least has progressed
in its development in many forms, although, as has been
stated above, some of the more slender species are ap-
parently restricted in their development. The fact that
a young form of Diemyctylus torosus shows a closer ap-
proach to the fossil condition than any other is of ex-
treme interest. It can be said with certainty that the
Diemyctylus torosus goes through the phylogenetic
stages in the development of its alimentary canal and in
my opinion we have here a representative in. the fossil
condition of one of these phylogenetic stages. But too
much importance can easily be attached to the close re-
semblances outlined above. It is to be remembered in
this, connection that the form of the alimentary canal is
so highly modified by the food habits and by the form of
the body of the individual animal that it will be difficult
to draw safe conclusions. On the other hand, so far as
we have ascertained, the form of the body of the sala-
manders has not changed essentially from that of their
forebears, the Branchiosauria, so there is no really good
reason why the form of the alimentary canal should have
undergone much change. |
SHORTER ARTICLES AND CORRESPONDENCE
OBSERVATIONS ON THE SPAWNING HABITS OF
HYDROIDES DIANTHUS
In connection with experiments and observations on the be-
havior of several species of annelids, chiefly the one above
named, covering a period of several years, it was my good for-
tune to, have seen the apparently somewhat rare phenomenon of
the spawning of these annelids under circumstances peculiarly
favorable for observation. So far as I am aware this has not
been made a matter of record, at least for this species, and some
inquiry among students of the group has failed to elicit any
detailed knowledge concerning the subject. It seems to be worth
while to submit my notes made at the time for at least a record
of fact, trusting that they may prove interesting to that extent.
The observations were made upon specimens in an aquarium in
my room at the Fisheries laboratory, Woods Hole, on July 30,1908.
A large colony, or aggregate, of these annelids had been freshly
obtained from near New Bedford, and had been transferred to
my aquarium about two hours before the spawning took place.
This was soon after noon of the date mentioned and the first ap-
pearance of the discharge took place about two o’clock. I was
sitting quietly by the aquarium observing the various aspects and
attitudes of the specimens, when a single individual was seen
to discharge suddenly a jet of whitish matter, which seemed
like a milky spume. It was so unusual as to attract imme-
diate attention, and within a few seconds the same specimen
repeated the process. Almost immediately a second specimen
made a similar discharge, ejecting a cloudy mass in a jet which
extended from twenty to thirty millimeters from the worm,
which at the time was extended perhaps about half that dis-
tance beyond the orifice of the tube. Almost immediately
another specimen exploded in similar fashion, and in less time
than it requires to make the record there were dozens actively
discharging clouds of eggs and sperms, until the entire mass
of water (at least six gallons), was milky with the generative
products. The eggs soon settled downward, indeed at the time
376
No.522] SHORTER ARTICLES AND DISCUSSION Stl
of ejection they were easily distinguishable, being ejected to a
less distance and rapidly inclining toward the bottom. The
spermatozoa, on the other hand, remained floating for an hour
or more after the discharge had ceased. The operation went on
for a period of some thirty or forty minutes, and then ceased
almost as suddenly as it had begun. Within an hour or so the
water had cleared of its milky aspect, the cells having settled
to the bottom of the tank.
The phenomenon was unlike anything which I had ever seen
among annelids. A single specimen would discharge at brief
intervals in jets like puffs of steam from an engine, and at the
height of the performance, when at least fifty specimens were
thus engaged, it was a spectacle of the most striking and exciting
character. If one could imagine some Lilliputian fire brigade of
similar numbers all intent on discharging intermittent streams
upon a miniature conflagration the impression could hardly be
more engaging!
Antecedent Behavior.—It had been observed at the time of the
transfer of the specimens referred to above, that there were quite
a number of large specimens which did not retract fully into the
tubes, as is usually the ease under such an operation. This as-
pect was more or less persistent during the operation of handling,
and if a specimen were compelled to fully retract by touching
it with the finger it would soon reappear and protrude the an-
terior portion of the body. This protrusion was likely to con-
tinue even after they had been put quietly into the aquarium.
It was this peculiarity which was engaging my attention at the
time the sexual explosions began. The query arose as to
whether it might not have been induced by some stimulus associ-
ated with the process of transfer and consequent exposure to
extraneous conditions. Accordingly I took occasion to subject
the colony to similar handling on subsequent days in order to
assure myself concerning the matter. But in no case was it
possible to induce a second discharge, or any simulation of the
sort. It seems highly probable, therefore, that the phenomenon
was perfectly normal, notwithstanding its apparently unusual
character. During the several years in which I had similar
colonies under observation in the same room for long periods it
would seem as if some symptom of the sort might have been
noted. In a letter from Professor J. Perey Moore I am assured
that
378 THE AMERICAN NATURALIST [ Vou. XLIV
Although I have kept large numbers of Hydroides literally bursting
with genital products under observation, I have seen natural oviposition
only twice.
Professor A. L. Treadwell has also stated that he has observed
a similar operation in the egg-laying of Dopatra. He says
further:
Whether the epidemie of egg-laying, in which when one starts the
others follow, is due to a similar stimulus acting on all of them at once,
or whether the first one stimulates the others, is not certain. I should
consider the latter the more probable explanation. I found that to be
the case in Podarke, where, if one started, the whole dish was apt to .
explode.
So far as could be ascertained under casual observation the
individuals participating in the performance were about equally
males and females, a further indication of the essentially normal
character of the phenomenon. It would seem as if specimens of
approximally similar age and condition of maturity ripen the
genital products at a given time, and under the appropriate
stimulus discharge them simultaneously.
The behavior will recall the somewhat similar exhibition of the
pololo worm, whose swarming and coincident spawning has been
described by several observers. May we not conclude that these
several phenomena are but varying expressions of a spawning
habit more or less common in annelids, and indeed not unknown
among other of the lower invertebrates, though differing of
course in various details?
It may be mentioned in conclusion that the ova discharged by
the worms at the time described were promptly fertilized and
developed in a perfectly normal and regular fashion.
Cuas. W. HARGITT.
SYRACUSE UNIVERSITY,
January 14, 1910.
NOTES AND LITERATURE
PROTOZOA
Doflein’s ‘‘Lehrbuch der Protozoenkunde.’’*—No group of ani-
mals affords a more direct approach to the problems of evolu-
tion than the Protozoa and few offer such varied data for their
discussion. The organism and the individual are here reduced
to lowest terms and the processes of growth, differentiation,
degeneration, regeneration and reproduction in the most varied
forms are found in astonishing variety and complexity. The
phenomena of overcrowding, rapid destruction, parasites and
parasitism, immunity, variation, speciation, isolation and per-
haps even mutation, with all of their consequences on structure
and reproduction, are illustrated in varying degrees of diversity
and completeness. It is therefore to be expected that a thor-
oughgoing review of the rapidly augmented literature of proto-
zoology by Professor Doflein will yield some new points of view
or at least a new perspective in which old conclusions and
hypotheses may be tested.
The biogenetic law, for example, in the opinion of the author
of the ‘‘Lehrbuch’’ is very doubtfully applicable to the Protozoa.
External factors profoundly affect the form and structure of
these simple organisms. Increased alkalinity of the water
changes Amæba limax to A. radiosa, as Verworn has shown.
Trypanosomes vary greatly in appearance and virulence, accord-
ing to the hosts in which they are cultivated, and in culture
media locomotor organs are lost and nucleus and blepharoplast
are shifted into new relations in the cytoplasm. Reproductive
processes are profoundly modified by temperature and chemical
media. The kind of food, according to Faure-Fremiet, affects
the structure of Vorticella. The form changes, therefore,
through which a protozoan runs in its life cycle ate to be re-
garded as moulded by external influence rather than by internal
factors of heredity and the production of similar structures is a
phenomenon of convergence rather than a proof of relationship
or descent.
This point of view determines Doflein’s treatment of certain
important questions. Thus the Suctoria form a class coordinate
166 Lehrbuch der Protozoenkunde.’’ Eine Darstellung der Naturge-
schichte der Protozoen mit besonderer Berücksichtigung der parasitischen
und cane came Formen. Zweite Auflage der ‘‘ Protozoen als Parasiten
und Krankheitserreger.’’ Von Dr. F. Doflein. Pp. x+914. Mit 825
Abbildungen im hak Jena, Gustav Fischer, 1909. M. 24. Geb. 26.50.
379
380 THE AMERICAN NATURALIST [ Vou. XLIV
with the Ciliata since the posterior circlet of cilia formed on the
bud of Acineta is a convergence phenomenon attendant upon the
free-swimming life of this stage rather than primarily an ances-
tral character indicating the derivation of the Suctoria from the
Ciliata.
Again the occurrence of flagellate-like stages in the life his-
tory of the Plasmodium, Babesia and Leishmania is not regarded
as of phylogenetic significance but as an independently derived
adaptive stage. The Hæmosporidia are therefore not transferred
from the Sporozoa to the Flagellata by Doflein as Hartmann and
others have argued. On the other hand, the trypanosomes are
regarded as having been derived from parasites of insects such
as Herpetomonas and Crithidia, whose forms they resemble in
culture media.
Doflein is skeptical about the specific distinctness of the vari-
ous pathogenic trypanosomes of mammals, though recognizing the
necessity of distinguishing them to avoid confusion, by their
hosts, occurrence and typical form in the blood of the host.
They are forms merely, not fixed species, and doubtfully even
incipient species. He holds as uncertain even the specific dis-
tinctions in the so-called gametes of T. gambiense and T. brucei
in the tsetse fly reported by Koch. He also rejects as hypothet-
ical the sexual cycle of T. lewisi in the rat louse reported by
Prowazek, regarding the evidence as based on abnormal stages
altogether too rare in occurrence to be typical sexual phases.
However the more recent work of Minchin, Baldry and Breinl
and Hindle tends to confirm the view that a sexual phase of the
parasite may occur in the insect host.
The Protozoa are regarded as a group whose limits are arbi-
trarily defined in the interests of economy in scientific work
rather than by structure. No sharp boundary line separates
then on the one hand, from the Metazoa—witness the spore of
Nosema or that of the Actinomyzxidia—or, on the other, from the
lower Metaphyta, as may be seen in the family Volvocidæ within
which numerous types of colonial organization have been evolved.
Not only do the Protozoa intergrade with Metazoa, the lower
algæ, moulds and fungi in morphological characters, but also in
physiological as well.
The author has for some years consistently maintained that the
lowest branch of the Protozoa is not the Rhizopoda as stated in
practically all text-books and manuals, but rather that the Masti-
gophora are to be regarded as lowest in the scale of organization.
This is based not only upon the occurrence of flagellated forms
in the gametes or other reproductive phases in the life history of
No. 522] NOTES AND LITERATURE 381
other classes, but also upon the relationships of the Mastigophora _
to the Bacteria. This relationship is traced by Doflein through
the Spirochetes which he names also Profiagellata, to Spirillum
and like forms. The suggestion is made that the Bacteria are
the equivalents of postulated Monera of Haeckel, though they
are far from resembling the forms actually described by him as
Monera, and that bacteria other than Spirillum should be in like
manner attached to other groups of protists to which they may
be related. Attention is called to the wide-spread occurrence
among Protists of chromidial cells, that is those seemingly with-
out nucleus but having finely divided and distributed chromatin
as seen in Bacteria, Oscillaria, Nostoc and Tetramitus and to
the appearance of this same type of distribution of chromatin
throughout the cell body among Protozoa at certain stages of
life history, especially in gametogenesis, though also in hunger-
stages and in pathological conditions. He wisely sounds a note
of warning against the domination in protozoology of the
morphological conception based upon the Metazoan cell, and a
note of caution against the possible interpretation of minute
parasites as chromidia. Ingested chromatin, as Martin has shown
in the Suctoria, also offers a pitfall for the chromidia hunter.
The theory of Schaudinn and Goldschmidt of the fundamental
dualism of the nuclear substance in the Protozoa, of the existence
side by side in the cell of sexual chromatin as pxeniplified 1 in the
micronucleus of Paramecium, of the generative chromidia of the
Foraminifera, and the nuclear membrane substance of Acan-
thometra and of somatic chromatin as seen in the macronucleus
of the ciliates, he regards as only a convenient morphological
schema not justified by either the comparative morphology or the
physiology of the Protozoa as a whole. He inclines rather to
Hertwig’s view of the unity of the chromatin substance.
Dr. Doflein acknowledges the great service which the theory
of Hertwig regarding the proportions of nucleus and cytoplasm
has rendered to science in the stimulation of research, but looks
to the future to assess its permanent value. He suggests that
depression stages resulting, on the one hand, in the regulating
processes of sexual reproduction or, on the other, in degeneration
and natural death, are exceptional ‘‘in der freien Natur.” To
the reviewer the astounding fluctuations' in numbers which the
organisms of the fresh-water plankton undergo in short periods
of time of three to five weeks, rising from minimum numbers to
1 Kofoid, C. A., 1908, ‘‘Plankton of the Illinois River,’’ Pt. Il, Consti-
tuent Organisms er their Seasonal Distribution, Bull. IU. State Lab. Nat.
Hist., yY. 4,
382 THE AMERICAN NATURALIST [Vou. XLIV
maximum of extreme proportions and falling away again with
equal or greater abruptness with accompanying high death rate
and appearance of sexual reproduction, especially in rotifers,
seem to be of a similar nature to the cycles with intervening
depression periods in laboratory cultures. These occur, more-
over, constantly and with surprising regularity in nature, in
both marine and fresh-water plankton among organisms of short
life-cycles.
Certain points in both Schaudinn’s and Hertwig’s theories of
sexual reproduction are combined with the earlier suggestions
of Biitschli in a theory of sex which has much in common with
that put forth by Geddes and Thomson. Living cells are con-
ceived as consisting of two groups of substance, one more fluid
in consistency concerned with the dynamic activities such as cell
division and locomotion, the other more solid, the reserve stuff
for the activities of life. In cell division these substances are
not equally distributed, reserve stuff predominates in some
(females) and the locomotor substance in others (males).
Morphological cell constituents for these substances are expressly
not postulated. An indifferent protozoan by division gives rise
to equal numbers of differentiated male and female individuals,
whose differentiation increases as division progresses. Fertiliza-
tion takes place in consequence of the physico-chemical attraction
of the two substances. The same chemical differences which
condition the form-distinetions of the gametes are also the prime
cause of the union in fertilization.
This theory naturally is easily applicable to the indifferent,
male and female forms of Trypanosomes and to the highly dif-
ferentiated sexual process and gametes of the Sporozoa generally,
but requires further elucidation to make it applicable to isogamy,
which is perhaps the primitive type of sexual reproduction and
one seemingly widespread among Protozoa.
Dr. Dofiein’s book is not only a great mine of carefully and
critically assembled information on Protozoa, but his facts are
marshaled with reference to the great problems underlying all
biological work in such a way as to stimulate further research.
CHARLES A. KOFOD.
UNIVERSITY OF CALIFORNIA.
CELEBRATING DARWIN’S GREATNESS AND
DARWINISM’S WEAKNESS
Tr will seem less ungracious now that the year has turned,
_ the one-hundredth year since Darwin’s birth and the fiftieth
No. 522] NOTES AND LITERATURE 383
-
since the ‘‘Origin of Species,’’ to say that the many memorial
meetings of the past year have left the definite impression on the
scientific world of having celebrated Darwin’s greatness and
Darwinism’s weakness. This is particularly true of the most
important and conspicuous two of these meetings of which the
books* under my eye at this moment are the permanent pub-
lished record.
The eleven addresses of the ‘‘Fifty Years of Darwinism’’
volume are, with one exception, by American naturalists. And,
with that same exception, and perhaps one other, all sound
clearly the note, now more pronounced, now more restrained,
of positive adverse criticism of the Darwinian factors in evolu-
tion. Each speaker first recognizes the lasting debt of science
and of himself to the immortal master, and then gently or fore-
fully proceeds to show how the master’s explanation fails to
explain, and to unload and display his own precious personal
baggage of ‘‘factors’’; factors of environment, of mutation, of
adaptation, of determinate variation, of isolation and what not.
It is, of course, greatly gratifying to us all, in these very times
of loud bewailing of the insufficiency both in quantity and in
quality of American output in research and natural-philosophic
thought, that each of the distinguished speakers at the chief
American Darwin memorial meeting had his own personal
baggage of evolution contributions to unload. ln a pinch we
can make, by discriminating concentration, a very creditable
showing for American activity in the biological ‘‘higher
thought.’’ ‘‘Fifty Years of Darwinism’’ certainly proves this.
The exception to the chorus of criticism and contributions to
substitute for the selection theories, or, at any rate, to come to
their imperatively needed aid because of some partial but fatal
weakness, is embodied in the address of the one English partici-
pant in the meeting. Professor Poulton, with a glorious patriot-
ism that surpasses that of the defender of imperialism, of an
hereditary legislative body or a staggering naval budget, defends
all of Darwinism against all of its critics.
For the rest, the names of Chamberlain, Coulter, Jordan,
Wilson, MacDougal, Castle, Davenport, Eigenmann, Osborn and
Hall show the scope and authority and interest of these addresses.
At the great English meeting there were more than twice as _
1‘‘ Fifty Years of Darwinism,’’ Eleven Centennial Addresses in Honor
of Charles Darwin, 1909, H. Holt & Co., New York, $2.00.
‘<Darwin and Modern Science,’’? Essays in Commemoration of the Cen- —
tenary of the Birth of Charles Darwin and of the Fiftieth Anniversary of
the Publication of ‘‘The Origin of Species,’’ 1909, eae Press, Cam-
bridge, and G. P. Foras ’s Sons, New York, $5.0
384 THE AMERICAN NATURALIST [VoL. XLIV
many essayists and the book that publishes them is twice as
_ large as the American book. Of the twenty-nine speakers eight-
een were British and eleven foreign (two American, six Ger-
man, one French, one Danish and one Dutch). Also the subject
covered was much broader than that of species-forming, heredity
and adaptation. It ranges from embryology to the genesis of
double stars; from the structure of the cell to the bases of reli- _
gious faith; from the movements of plants to the evolution of
matter. The greatest Neo-Darwinian and one of the greatest
Neo-Lamarckians were there; as were the most radical mechanic-
alist, the most advanced monist, the most ardent Mendelian,
the founder of the mutations theory, one of the most influential
of modern philosophers, and the four distinguished sons of the
immortal master. It was a more representative gathering than
the American one if for no other reason—though there are other
reasons—than that twenty-nine men are likely to be more repre-
sentative than eleven, or that six nationalities are likely to repre-
sent more than two.
But the points in common to both meetings were exactly those
indicated by the title of this review. And these are the points
common to almost all present-day critical discussion of evolution
and its explanations. Darwin’s explanations are no longer suffi-
cient; they never were, of course, but they seemed so. But
Darwin himself as man and worker, as example, as real estab-
lisher and greatest champion of the whole organic evolution con-
ception, shines ever more brilliantly in the heavens of history.
De Vries, Weismann, Bateson, Haeckel, Lloyd Morgan, Goebel,
Klebs, Sedgwick, W. B. and D. H. Scott, Loeb, Schwalbe, Arthur
Thomson, Strassburger, Joseph Hooker, Thiselton-Dyer, Gadow,
Francis and George Darwin, Poulton, and the nine others that
represented geology, physics, philology, history, sociology, phi-
losophy and religion, make up an imposing list of names in
modern biological science. It is the list of the essayists at the
Cambridge meeting. Add to it the names, already catalogued,
of the participants in the American meeting, and the possessor
of the two books that contain these many addresses and essays
may confidently assume himself to be in possession of the latest
authoritative word in evolutionary matters.
Vitis i.
STANFORD UNIVERSITY,
February, 1910.
Be
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4. American Monthly Microscopical Journal, vols. 1-20 (1888-1899), of which
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10. Gaudry, A. Animaux fossiles et géologie de l’Attique. 2 vols., folio,
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By CHARLES J. CHAMBERLAIN
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HE first complete manual to be published’ on the subject of botanical micro-
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Will no doubt find a place in every well-regu- It an excellent book for the individual
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private rat klean —Plant World.
A Laboratory Guide in settee
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CLEAR and concise presentation of bacteriological technique, designed prin-
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Notes and Queries.
and pAn
ADDRESS DEPT. 64
Chicago THE UNIVERSITY OF CHICAGO PRESS New York
VOL. XLIV, NO. 523°
m
g dał Hy
THE
AMERICAN
NATURALISI
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
A Consideration of the “Species Plantarum” of Linnaeus as a Basis for
the ing Point | of f the Nomencisture o cryptogams. Pro fen sor W.
G. FARLOW z z
Notes on Some Banii Fishes. E. W. Gudger
met the betas of oe VERTER on we Reproduction of Daphnia. Dr.
McCLEND
Are Fluctuations ‘iit ? Dr. HARRY H. LOVE - - = - -
Inheritance in Potatoes. Fonai r EDWARD M. EAST
me Articles = a: The Age of ‘Bpeed Sires: "Professor
Notes an : Rus sso on Sex- Darimi d Anificial Modifica-
SEPE 4
tion of the Mendelian a Professor W. E. CASTLE ; The Bubonic Eae,
Professor H. B. WARD; Desert Plants, Professor WILLIAM L. BRA
THE SOIENCE PRESS
LANCASTER, PA. GARRISON, N. Y.
NEW YORK: SUB-STATION 84
JULY, 1910
The American Naturalist
MSS intended for publication and books, etc., intended for review should be
sent to the Editor of THE AMERICAN NATURALIST, Garrison-on-Hudson, New York.
Articles containing research work bearing on the problems of organic evolu-
tion are especially welcome, and will be given preference in publication.
ne hundrea reprints of contributions are supplied to authors free of charge.
Further reprints will be supplied at cost.
THE SCIENCE PRESS
Lancaster, Pa. Garrison, N. Y.
NEW YORK: Sub-Station 84
Entered as second-class matter, April 2, 1908, at the Post Office at Lancaster, Pa., under the Act of
Congress of March 3, 1879.
TO ORNITHOLOGISTS Fifty Years ot Darwinism
AND MUSEUMS Comprising the eleven addresses in honor
of Charles Darwin delivered before the
W. F. H. ROSENBERG American Association for the Advance-
ment of Science.
Importer of Exotic Zoological Specimens
8vo, 274 pp. $2.00, net.
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Begs to announce the publication of a new ue
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THE
AMERICAN NATURALIST
Vou. XLIV July, 1910 No. 523
A CONSIDERATION OF THE ‘‘SPECIES PLAN-
TARUM’’ OF LINN AUS AS A BASIS FOR
THE STARTING—POINT OF THE
NOMENCLATURE OF
CRYPTOGAMS!
PROFESSOR W. G. FARLOW
Harvarp UNIVERSITY
Ar the Congress held in Vienna in 1905 it was voted
to adopt Linnzus’s ‘‘Species Plantarum,’’ 1753, as the
starting-point of the nomenclature of flowering plants
and the question of the starting-point for that of crypto-
gams was referred to the congress to be held at Brussels
in May, 1910. The adoption of the ‘‘Species Plantarum’’
was endorsed practically by so large a proportion of
phenogamic botanists that its acceptance came as near
being universal as could ever be expected in such a case.
It may be assumed therefore that the ‘‘Species Plan-
tarum”’ is well adapted to serve as a basis for the nomen-
clature of phenogams. Were it true that it is as well, or
nearly as well, adapted to serve as a basis for the nomen-
clature of cryptogams, there would be no hesitation on
the part of eryptogamists in adopting it also. If it is not,
there is no reason why they should feel under any obliga-
tion, for the sake of a merely formal uniformity in nom-
enclature, to follow in the steps of other botanists.
In the first place we may ask why it is that the ‘‘Species
1 Invitation papers read at the sixteenth annual meeting of the Botanical
Society of America.
385
386 THE AMERICAN NATURALIST [Vou. XLIV
Plantarum’’ should be considered to be well adapted to
the requirements of phenogamic botanists. The fact
that it was the first work in which the binomial nomen-
clature was methodically applied is a sufficient reason
why no work issued prior to 1753 should have been
adopted as a basis of nomenclature, but that fact alone
is not a sufficient reason for.the adoption of the ‘‘Species
Plantarum”’ itself. An examination of that work shows
also other merits which should recommend it. It is an
admirable summary by the leading systematist of his
day of several hundred genera and some thousands of
species found not only in Europe but also in North Amer-
ica and other more remote parts of the world. In fact,
on glancing over its pages one is surprised at the large
field covered by Linnzus and the large number of exotic
species which are included in the work. In the numerous
editions of the ‘‘Species’’ issued at intervals of a few
years until as late as 1830, some under the title of ‘‘Sys-
tema Vegetabilium’’ and ‘‘Systema Plantarum,’’ the
Linnean traditions were handed down with additions and
annotations by well-known botanists, so that there is no
gap separating the original edition from the date of the
appearance of the first volume of De Candolle’s ‘‘Pro-
dromus’’ in 1824. It should also be borne in mind that
under the careful guardianship of the Linnan Society
of London, the Linnean herbarium is still in existence
and accessible to botanists. It is therefore not difficult
to see that for a basis of nomenclature of flowering
plants the ‘‘Species Plantarum’’ was well chosen.
f we turn now to the ecryptogams of the ‘‘Species’’
we find a very different state of things. To those who
have not examined the ‘‘Species’’ with reference to this
point it might seem that the eryptogamists for the sake
of uniformity might be willing to make some sacrifice.
For such persons a comparative examination of the
phenogams and eryptogams in the ‘‘Species’’ may be of
interest. For this purpose I have prepared a table show-
ing the number of genera and species in the two groups.
No. 523] THE “SPECIES PLANTARUM ” 387
The number of genera can be determined without diffi-
culty. The counting of the species is less easy since in
some cases it is not quite certain whether under a given
name Linnzus intended to indicate a species properly
speaking or merely a form or variety. In my enumera-
tion I have included only those forms clearly designated
as species, omitting subspecific forms. That the enu-
meration here given is conservative is shown by the fact
that, while according to the ‘‘Codex Linnzanus’’ the
total number of species in the ‘‘Species Plantarum”’ is
5,938, the total of my list is 5,247, divided as follows:
Genera, Species.
E icy inte fe EE ORAL ee ee 1,049 4,630
Daaa i isc Seva E E 50 617
E E E E a es 1,099 5,247
Of the 50 genera and 617 species, 16 genera and 189
species are Filices and there are in addition 24 species
of the genus Lycopodium which was placed by Linnæus
in Musci. Among the Filices are to be found numerous
characteristic species of America and the tropics and in
this respect the treatment of the group by Linnæus is
quite comparable with his treatment of phænogams. For
nomenclatorial purposes the Filices and Lycopodium are
even at the present day treated in the same manner as
phænogams, and it is a well-known fact that it is the cus-
tom to unite the vascular eryptogams and the phænogams
in floristice works. So far as we are now concerned the
higher cryptogams need not enter into the discussion,
but from the nomenclatorial standpoint must be classed
with phænogams and there are therefore left 404 species
and 44 genera for all the Bryophytes and Thallophytes
described in the ‘‘Species Plantarum.’’ But even in this
small number is included the genus Spongia under Alge
with 11 species, of which at least the greater part are not
even plants in any sense. Furthermore, among the Bryo-
phytes and Thallophytes there are almost no extra-
European species and of the European species a great
388 THE AMERICAN NATURALIST [ Vou. XLIV
proportion are northern. In short, although as far as
phznogams are concerned the ‘‘Species Plantarum”’ in-
cludes characteristic representatives of different parts
of the world, as far as the Bryophytes and Thallophytes
are concerned it represents only a limited European
flora.
The question may perhaps be asked by those who have
not studied specially any group of non-vascular crypto-
gams: Although the number of non-vascular crypto-
gams in the ‘‘Species Plantarum’’ is very much smaller
than that of phenogams, is it not perhaps the case that
the ratio represents approximately the relative size of
the two groups in nature? It has been the custom to
state that the phenogams outnumber the cryptogams,
some even saying that they are much more numerous.
Such statements are based solely on an enumeration of
described species and fail to give information as to the
probable actual number of species. It is not possible to
give figures on the subject which are up to date and the
statistics of even a few years ago are of slight value, for
it is only within a few years that the study of eryptogams
has been pursued in other parts of the world than Europe
or, to a less extent, North America. We can probably ob-
tain a more correct opinion if we consider probabilities.
The number of known species of Musci and Hepatice has
been very much increased in the last few years, and al-
though the bryological flora of Europe and North Amer-
ica is now so well known that no very large number of
new species is to be expected there, in other parts of the
world and especially in the tropies, it is evident that the
work of exploration conducted by trained specialists will
bring to light a very large number of new species. The
same is true of lichens. In alge a very great increase of
species is less to be expected, partly for the reason that
the region of growth of marine algæ, pelagic species ex-
cepted, is more limited than that of land plants. But
even in alge, it is probable that the known species will
be considerably increased.
No. 523] THE “SPECIES PLANTARUM” 389
The fungi offer a better field for comparison than
other groups. It is certainly true that the number of de-
scribed species is decidedly smaller than that of phano-
gams. Are we then to conclude that there are fewer
fungi in the world than there are phenogams? By no
means, for there is a possible inference which may be
drawn from a knowledge of the distribution of fungi to
which, it seems to me, great weight should be given.
Year by year the number of known parasitic fungi goes
on increasing and, although we can not assume that prob-
ably every phenogam has its parasite, the proportion
which have is constantly increasing. We also know that
some species have not only one but many parasites and,
as a rule, the species which from their economic value
have been most carefully studied are the hosts of many
fungi. As an instance I may mention the species of the
genus Vitis, on which several hundred species of fungi
are known to grow, some, to be sure, found also on other
plants, but a large number peculiar to this genus.
When all genera have been studied as carefully as Vitis
we shall undoubtedly find that the number of parasitic
fungi in existence is enormous. If to the parasitic we add
the thousands of saprophytic fungi, it may well be asked
whether eventually it will not prove to be true that the
number of species of fungi is as great as that of phæno-
gams. It seems to me that it should be plain to every one
that if in the ‘‘Species Plantarum’’ the proportion of
phenogams to eryptogams is about ten to one, we must
admit that although the work is sufficiently comprehen-
sive to serve as a basis for the nomenclature of the
former, it is entirely inadequate in the case of the latter.
I have referred to the restricted range of the species
of eryptogams described by Linneus and to their small
number. If we go farther and examine the character of
the descriptions themselves we find that they are in many
cases vague and unintelligible, which is nothing more
than might have been expected in that day before the
scientific study of the group had really begun. The Alge
390 THE AMERICAN NATURALIST [ Vou. XLIV
in particular are from the modern point of view a strange
medley. The genera Jungermannia, Targionia, Mar-
chantia, Blasia, Riccia and Anthoceros I have in my enu-
meration included in Bryophytes where they properly
belong, although they were placed by Linnzus in Alge as
well as the genus Lichen with 80 species. The genus
Tremella with 7 species was also included in Algz, al-
though as far as the scanty descriptions can be identified,
3 are species of fungi, 3 alge and one a lichen. Some
of the 12 species of Byssus are alge, but the majority
it is impossible to recognize. Of the 11 species. of
Spongia nearly all are animals.
Of the later editions of the ‘‘Species Plantarum”’ the
fourth, according to some the fifth, has a partial revision
of the fungi by Link and of the mosses by Schwaegrichen,
but as these parts were not published until 1824-30 and
do not follow in any way the original edition of Linnzus,
so far as priority of nomenclature is concerned, they
need not be considered here. Of the ‘‘Systema Plan-
tarum,’’ Reichard, 1780, and the ‘‘Systema Vegetabil-
ium’’ by Gmelin, 1796, by Persoon, 1797, and Sprengel,
1827, it can be said that although they include more
species than the original edition of Linnæus they are
open to the same objection and, as will be seen later,
the dates of their publication are so near those of far bet-
ter works that their nomenclatorial value is of trivial im-
portance. If I have dwelt at what may seem too great
length on a consideration of the value of the ‘‘Species
Plantarum”’ as a basis of nomenclature, it has been for
the purpose of trying to make clear to those to whom
uniformity in nomenclature seems to be of the first im-
portance, why it is that to expect eryptogamists to adopt
the ‘‘Species’’ on the same basis as do phenogamists is
unreasonable. To the latter the ‘‘Species’’ represents a
fundamental treatise; to the former a very meager and
unsatisfactory list of plants belonging to groups of which,
in the time of Linnæus, there was really no exact knowl-
edge.
No. 523] THE “SPECIES PLANTARUM ” 391
One would be glad to adopt as a basis of nomenclature
some one work which bears the same relation to crypto-
gams as does the ‘‘Species Plantarum’’ to phænogams,
but there has never been any such work and there never
will be, for a very good reason. The phenogams form a
homogeneous group. The eryptogams do not, but consist
of a number of different groups, and the fundamental
works relating to them appeared at different dates, all,
however, considerably later than 1753. The specialists
who study bryophytes, lichens, alge and fungi are en-
tirely justified in adopting different works as a basis of
nomenclature. The question they should ask is: What
was the first work on bryophytes, on lichens, on alge, on
fungi, in which those groups were scientifically and com-
prehensively treated?
It is not possible to enter at this time on a general con-
sideration of this point. Although that part of Linneus’s
‘*Species’’ which relates to bryophytes appears to have
greater value than that which relates to thallophytes,
since for one reason his citations of Dillenius’s figures
help one to understand to what plants the brief descrip-
tions were applied, it must certainly be admitted that
Hedwig’s ‘‘Species Muscorum,’’ of which the first vol-
ume appeared in 1801, is the fundamental work on mosses
and that Hedwig, with whom the scientific study of
mosses began, may be called the Linneus of bryology.
Acharius stands in the same relation to lichenology, and
it is a question to be settled by lichenologists whether the
‘‘Lichenographia Universalis’? of 1810 or the earlier
‘*Methodus’’ is to be given the preference. For algz,
the ‘‘Systema Algarum’’ of ©. A. Agardh has been sug-
gested. It is, however, out of the question to refer more
in detail to the groups just mentioned, but it will be suffi-
cient if we consider the case of fungi somewhat more
minutely, although the subject is perplexing and compli-
cated even to those more particularly interested in this
group and probably wearisome to others.
In the ‘‘Species Plantarum’’ 1,073 pages are given to
392 THE AMERICAN NATURALIST [Von XLIV
phænogams, 15 pages only are given to fungi, including
Agaricus 27 species, Boletus 12, Hydnum 4, Phallus 2,
Clathrus 3, Elvela 2, Peziza 8, Clavaria 8, Lycoperdon 9
and Mucor 11. To these must be added 3 of the species
of Tremella placed by Linnæus in algæ, making 89 fungi
in all. Of these not one is extra-European and only 8
are cited as growing in Italy or southern Europe.. To con-
sider that a work of such a limited scope should serve as
a basis of nomenclature of a group whose species are
numbered by thousands seems to me preposterous. All
that we can say of the fungi in the ‘‘ Species Plantarum”’
is that they show plainly that in 1753 next to nothing was
known of that large group, and one may be pardoned for
saying that in what Linneus wrote about fungi he was
not a Linneus. We must search elsewhere for a funda-
mental work on the subject. In the later editions of the
‘<Species’’ and the ‘‘Systema Vegetabilium,’’ as I have
said, the treatment of fungi is not in any way satisfac-
tory, and it was not until about fifty years after the pub-
lication of the ‘‘Species’’ that there appeared anything
which could be called a general and comprehensive work
on the species of fungi. If mycologists were asked who
exerted the greatest influence in placing systematic my-
cology on a firm basis they would say Elias Fries and the
‘‘ Systema Mycologicum,’’ of which the first volume ap-
peared in 1821, had an influence in shaping the study as
no other work has had. In saying this I do not wish in
any way to underrate the value of the ‘‘Synopsis Meth-
odica Fungorum”’ of Persoon, issued in 1801, but of the
two I think that the ‘‘Systema’’ is the one which has had
decidedly the greater influence in shaping the progress
of descriptive mycology. In its three volumes together
with the two volumes of the ‘‘ Elenchus’’ which is a part
of the ‘‘Systema,’’ we find for the first time an account
of the mycological flora of a considerable portion of the
world rather than an account of certain orders of fungi,
mainly of Europe. In the ‘‘Epicrisis’’ of 1836-38, the
‘‘Summer Vegetabilium Scandinavie,’’ 1849, and the
No. 523] © THE “SPECIES PLANTARUM ” 393
‘‘ Hymenomycetes Huropei,’’ 1874, we have important
revisions and commentaries by Fries of his earlier work.
The ‘‘Icones Selecte Hymenomycetum’’ include 200
plates executed under his supervision of species which
cannot well be studied by dried specimens alone. The
herbarium of Fries is still at Upsala and the ‘‘Sclero-
myceti -Leuciz,’’ a collection of 450 small parasitic
species, is to be found in herbaria in Europe and this
country and has been the subject of critical commentaries
by several botanists. The fact that the volumes of the
‘*Systema’’ did not appear in the same year does not
appear to me to present a serious practical difficulty, as
Volume I containing Hymenomycetes appeared in 1821
(except Solenia, Cyphelia and the Tremellinex, in Vol.
II, 1822), Volume II, section 1, with Discomycetes ap-
peared in 1822, Volume II, section 2 (p. 275), with Gas-
teromycetes (Angiogasters) and Pyrenomycetes in 1823,
Volume III, sectio prior with Gasteromycetes, Myxo-
mycetes and Perisporiacee in 1829, and Vol. III, sectio
posterior (p. 261), with Fungi Imperfecti in 1832.
The ‘‘Synopsis’’ of Persoon, although to be preferred
to any previous work, is considerably less extensive in
the number and range of the species given than the
‘‘Systema,’’ the number in the latter being about two
and a half times as great and, in general, the ‘‘Systema’’
presents a decidedly more modern way of treating the
group. A fulier consideration of the comparative merits
of the ‘‘Systema”’ is out of the question in this place as
it would require more time than can be allowed and be-
cause the details are such that they could not be readily
followed except by mycologists who have studied the
question minutely. I have no right to encroach further
on your patience and need only, in conclusion, repeat that
the ‘‘Species Plantarum”’ is quite unfit to serve as a basis
for the nomenclature of fungi, and that the ‘‘Systema’’
of Fries seems to me to be better adapted for the purpose
than any other work. In any ease, to go back earlier than
the ‘‘Synopsis’’ of Persoon would only tend to perpetu-
394 THE AMERICAN NATURALIST [ Vou. XLIV
ate the present uncertainty and confusion, and would
open the door to those who, regarding nomenclature as
an end in itself and not merely a means by which the
necessary evil of naming plants can be reduced to a min-
imum, devote time and labor to the undesirable task of
unearthing names which are at the best uncertain, at the
sacrifice of names which have been in universal use for
many years, and whose meaning is perfectly clear. To
my mind the object should be, not to attempt to seek per-
fection in authority and priority—a hopeless task—but
rather to select the best solid basis in some comprehen-
sive work. Even then, there is the question of genera
conservanda and I believe that, whatever work or date
is adopted, it will be most desirable to adopt a list of
genera conservanda. There is nothing illogical in this
and practically there are great advantages unless one be-
lieves in the theory that mere changing of names is a
merit in science. That theory I certainly do not accept,
but hold that the fewer changes of names the better.
It has been my misfortune never to have found any-
thing perfect. Some of my friends have perfect systems
of classifications of books, of herbaria or of plants. In
trying to apply perfect methods I always recall a visit
in company with Sir Joseph Hooker to an establishment
not a thousand miles from here. The person in charge
said, ‘‘We think we have a perfect museum case which
we would like to show you.” ‘‘Yes,’’ said Sir Joseph, ‘‘I
am always glad to see what I have never seen. But what
do you keep in the case?’’ A key was produced, but by
no amount of coaxing or forcing could the case be opened.
‘‘Yes,”” said Hooker, ‘‘I presume that it is perfect, but I
prefer cases which open.” The same remark would
apply to a good many systems. They are perfect until
we try to find out what is in them.
NOTES ON SOME BEAUFORT FISHES—1909!
E. W. GUDGER
State NORMAL COLLEGE, GREENSBORO, N. C.
Tue following observations were made while working
at the Station of the Bureau of Fisheries at Beaufort,
N. C., from May 26 to July 6, 1909, and are recorded in
brief in the card catalogue of fishes in the laboratory.
While they are but membrana disjecta, they are published
in the hope that they may not be devoid of value to those
interested in fishes.
These fishes, with the exception of the ones specifically
noted from other localities, were taken at the Narrows of
Newport River. This is a small stream, whose sunken
lower valley is an estuary opening into and forming a
part of Beaufort Harbor. The Narrows, distant some
seven miles in a northeasterly direction from the labora-
tory, are at the head of the estuary. Here are a number
of ‘‘rocks’’ or reefs built by oysters out on the mudflats.
Their names, as one comes to them in going up stream,
are Lawton’s, Cross and Rockfish Rocks, and a fourth
one not named. These reefs, extending out at nearly
right angles from the shore, give the channel a very tor-
tuous course. Above them the mudflats spread out so
shallow that the river is not navigable save for small
boats and by them only at high water. The waters of the
ebb tides, collected off these mudflats and largely confined
by the reefs to this narrow channel, surge around these
points and have scoured out deep holes. Here are to be
found large numbers of various fishes, which go up the
river to feed on the mudflats and at low tide drop down
into these holes. There is no seining ground at Beau-
fort, known to the writer, where so many different species
of fishes may be taken at a single haul of the seine as at
the ‘‘Rocks’’ at the Narrows of Newport River.
It is interesting to note that the water at the Narrows
‘Published by permission of the Commissioner of Fisheries.
395
396 THE AMERICAN NATURALIST [Vou. XLIV
is markedly brackish, owing to the large amount of fresh
water brought down by the river. This, coming from the
cypress swamps a few miles away, has a decidedly yellow-
ish tinge, the so-called ‘‘juniper water.’’ In density this
water ranges from 1.0072 just after one of the tropical
downpours to which Beaufort is subject, to 1.0184 when
only the normal amount of fresh water is brought down.
Ten observations for last summer, which was a normal
one from the standpoint of rainfall, give an average den-
sity of 1.0153. The average temperature of the water at
the time of these observations was 23.6° C. at a depth of
three to five feet.
From May 26 to June 12 we constantly caught large
numbers of small menhaden, Brevoortia tyrannus, aver-
aging about four inches in length. These are probably
young of the previous fall spawning. The average size of
adult menhaden is about 12 inches. The largest ever
taken at Beaufort by the writer was 15 inches long. The
record fish for the Atlantic coast is 18 inches in length.
The writer has taken hundreds of gaff topsail catfish
at the Narrows, some quite large, but the record was
broken on May 27 by the capture of a female, whose
length from tip of nose to tip of caudal fin was 244 inches,
and whose girth back of the dorsal was 13 inches. The
abdomen was distended balloon fashion by the enormous
ovary which ceeupied almost all of its interior, crowding
and displacing the stomach and intestine as it enlarged.
This ovisae, after being three days in 10-per-cent. for-
malin, measured 74 inches in length and 9% inches in
girth, and weighed 435 grams.
On May 27, at Cross Rock, we took a large tripletail or
flasher, Lobotes surinamensis. Its length all over was
25 inches, its depth (body only) 103 inches. Unfortu-
nately there was at hand no means for weighing it.
Other large fish of this kind recorded in the card cata-
logue at the laboratory are, one 21 inches long and 84
inches deep, another 184 inches long, a third 18 inches
long. All were taken by the writer; the last in the pound
net two miles up Newport River, the others at the Nar-
No. 523] NOTES ON BEAUFORT FISHES 397
rows. Smith in his ‘‘Fishes of North Carolina”? notes
three large specimens from Beaufort: one of 25 inches,
another of 23 inches, and a third (length not given) which
weighed 11 pounds.
On May 31, a 144 inch specimen of the cutlass-fish,
Trichiurus lepturus, was taken at Rockfish Rock. On
June 5, another specimen, 15% inches long over all, was
taken at the same place. These young fish showed clearly
the oral breathing valve, which is perhaps more plainly
seen in the mouth of the adult than in any other fish
known to the writer. One of these fish had had a bite
taken out of its dorsal fin and region just over the hinder
edge of the pectorals. This has failed to regenerate and
the wound had healed, leaving a crescent cut out of the
fin.
Not only are these the smallest specimens of this fish
ever taken at Beaufort, but they are further interesting
because of the fact that both so amply justify the name
‘*hair-tail,’’ since in each the tail is prolonged backward
in a long delicate whiplash-like organ, much slenderer in
proportion to the size of the body than is the case in the
adult. They were probably two, quite certainly not more
than three years old. The writer has obtained eggs by
‘*stripping’’ this fish in August, and sperms from males
caught in July. Nothing, I believe, is known of the em-
bryology of the fish, but Lutken,? in 1880, figured and
described the young of two allied forms, Gempylus ser-
pens and Neolotus tripes.
On the same date and at the same place as the preced-
ing, there were taken four specimens of the cow-nosed
ray, Rhinoptera bonasus. These were all about of one
size, averaging 24 inches wide. A female after being
clubbed on the head until insensible, gave birth, while
being cut open, to two young measuring 8} inches long
and 134 inches wide. This premature delivery of the
young, brought about by muscular contraction due to re-
2 Smith, H. M., ‘‘The Fishes of North Carolina,’’? N. C. Geological and
Economic Survey, Raleigh, 1907.
*Lutken, Chr., ‘‘Spoila Atlantica,’’ Danske Videnskabernes Selskabs
Skrifter, 5te Raekke, Natur. og. Math. Afdeling, Table ITI., figures 3-8.
398 THE AMERICAN NATURALIST [ Von. XLIV
flex action, is by no means unusual, the writer having
noticed it on several occasions in both butterfly and sting
rays. Not infrequently, however, the young are born
while the mother is being killed, the pain causing spas-
modic contractions of the muscles of the uterus.
In this connection it is interesting to read in Schom-
burgk* as follows:
I have frequently observed that the rays, no doubt in consequence
of the anguish when secured and transfixed by the poles (harpoons),
brought forth their young ones.
A similar occurrence was once noticed by Dr. S. West-
ray Battle, of Asheville, N. C., who related it to the
writer. The young slip very readily out through the gen-
ital orifice, and on several occasions (July 29, 1902, for
the first time), I have delivered the mother of her young
by manipulating her abdomen in the manner familiar to
spawn takers. The young are rolled up in tubes, one
pectoral fin forming the inner lining of the tube, the
other the outer; i. e., the fish is rolled up like a sheet of
paper beginning at the edge of one pectoral. It is inter-
esting to note that the teeth of these young rays were
hard and fit for service, and the spines able to produce a
wound.
On May 29 I found on Fort Macon Beach, about one
half mile south of the concrete breakwater, a dead and
half dried specimen of Raja eglanteria, called ‘‘brier
ray’’ because of the curved prickles with which its dorsal
region and especially its tail are covered. This is the
‘*clear-nose’’ of the fishermen, and the dried specimen
in question fully justified the appellation, since the mem-
brane joining the rostral cartilages to the pectoral fins
was translucent almost to the point of transparency.
The fontanelles of the skull, especially the anterior one,
were clearly marked out. The total length of this speci-
men from tip of nose to broken-off end of the tail was 19
inches: the pectorals were rolled up and so hard that it
was impracticable to ascertain the width of the fish.
This is the only specimen of the ray which the writer
* Schomburgic, R. H., ‘‘Fishes of Guiana,’’ Part II., in Jardine’s
Naturalist ’s Library, 1
No. 523] NOTES ON BEAUFORT FISHES 399
has seen, and the only one noted in the card catalogue at
the laboratory. Of this species, Smith® wrote in 1907:
It has not previously been recorded from North Carolina, although
it doubtless oceurs along the entire coast of the state. At Cape Look-
out, on April 22, 1904, the author observed numerous specimens on the
beach and was informed that many are caught in the deep-water gill
nets set in that region.
On June 5 a three-foot male Scoliodon terranove, the
ordinary sharp-nosed shark found everywhere in the
harbor, was captured at Lawton’s Rock. Noticing that
he had the tail of an ordinary eel, Anguilla chrisypa,
sticking out of his mouth, I opened him and found in his
stomach the half-digested remains of two other eels,
smaller than the first. This observation leads one to con-
jecture whether eels constitute a steady article of diet
for sharp-nosed sharks.
Lest it should seem strange for the shark to be taken
and to die in the boat with this half-eaten fragment of
food in his mouth, it may be of interest to add that I have
seen in the hold of a menhaden schooner, sharks of the
same kind literally full of menhaden, stomach, gullet and
mouth; and with menhaden impaled on the teeth half in
and half out of the closed mouth. The menhaden fisher-
men report that this is a very common experience with
them.
The spotted sting ray, Aétobatus narinari, was first de-
scribed from Brazil by George Marcgrave in his ‘‘ His-
toriæ Rerum Naturalium Braziliw,’’ published in ‘‘ His-
toria Naturalis Brazilie’’ by William Piso and George
Maregrave at Lugduni Batavorum et Amstelodami, in
1648. In his description of this ray, Marcgrave gives a
figure which is perfectly recognizable and indeed is ad-
mirable, considering the time when it was drawn.
Yarrow® reports that in his day this ray was very com-
mon at Beaufort. But so rare is this fish there at the
present time that, in seven summers’ fishing, I had never
seen one until a female was taken at Rockfish Rock on
€ Smith, H. M., op. cit.
€ Yarrow, ‘‘Notes on the Natural History of Fort Macon, North Caro-
lina, and Vicinity,’’ No. 3—Fishes, Proc. Acad. Nat. Sci. Philadelphia,
Vol. XXIX, 1887.
400 THE AMERICAN NATURALIST [ Vou. XLIV
June 12, and then I was quite sure that I had found a new
species until the director of the laboratory, Mr. Henry D.
Aller, positively identified it under the above name. Its
width across the utmost reach of the pectorals was 26
inches; length, end of snout to tip of ventrals, 18 inches;
length of tail, root to tip, 404 inches; tail with two spines,
length over all 564 inches (tail inserted between bases of
ventrals) ; width between eyes 4 inches.
The most interesting thing about this ray apart from
its color is the very unusual structure of its jaws.
Whereas, in ordinary rays with pavement teeth, the
upper and lower jaws are practically duplicates, in this
ray while the upper jaw is of the ordinary shape, the
lower is drawn out into a tongue-shaped organ protrud-
ing beyond the lips. These would seem to be especially
fitted for cracking clams, which dissection proved to con-
stitute its chief food. It should be remarked in passing
that the jaws of Aétobatus are noticeably smaller than
the jaws of an ordinary ray of the same size.
On July 3 Mr. Russell J. Coles, of Danville, Va.,
caught in the bight of Cape Lookout and very kindly
brought to the laboratory another ray of this species.
This was also a female whose measurements were as fol-
lows: Width, 233 inches; length, body only, 16 inches
tail, 354 inches long and provided with two spines; width
between eyes, 34 inches. Mr. Coles, notwithstanding his
long experience as a fisherman for sharks and rays at
Beaufort and Cape Lookout, thought that he too had
caught a new species.
As a further evidence of the scarcity of this ray in the
Beaufort region, it.may be noticed that the card catalogue
of the laboratory has records of but two other specimens.
In 1901 some fishermen took on the outer or channel side
of Shark Shoal, in the deepest part of Beaufort Harbor
an Aétobatus narinari whose dimensions were as follows:
Width, 4 feet; length, nose to ventrals, 2 feet and 2
inches; tail, 4 feet and 8 inches long; total length about 6
feet and 6 inches (allow for insertion of tail between ven-
trals). On August 3, 1909, Mr. C. F. Silvester, of Prince-
No. 523] NOTES ON BEAUFORT FISHES 401
ton, N. J., took a specimen inside the hook of Cape Look-
out. Of this, however, no measurements were made.
Considerable numbers of sting and butterfly rays,
Dasyatis say and Pteroplatea maclura, were taken at the
Narrows. The females of these were commonly found to
have gravid uteri. At the beginning of my season’s
seining, the eggs had on them young in very early stages
not longer than 10-12 millimeters, the ‘‘selachian stages’’
of Aleock. Two eggs were found having what seemed to
be membranous egg shells like those found on teleost
ova, and one had the ends twisted into chalaza-like struc-
tures similar to those in a hen’s egg. Alcock seems to
have found similar structures in Carcharias melanop-
terus, a viviparous shark of the Indian Ocean. He
writes:
Each young one lay, head forwards, in its own separate compart-
ment of the uterus, in which, further, it was completely enveloped in
a very delicate membrane of its own. This delicate envelope is evi-
dently the pseudamnion of Parker, which, according to that author,
corresponds with the horny egg-shell of viviparous Elasmobranchs.
Those uteri, which contained embryos having the yolk
sac gone or reduced to a mere string, had their whole
inner surface crowded with villi, shaggy with them. Both
the villi and the deeper layers of the uteri were tremen-
dously vascularized, and the whole uterus in any speci-
men was greatly distended by this unwonted blood sup-
ply. Uteri containing young as above described were
filled with and had the young bathed in a milky fluid evi-
dently secreted by the villi (in the absence of a placenta)
as nourishment for the embryos until the time of hatch-
ing. According to Alcock? this ‘‘milk’’ is taken through
the open spiracles of the Indian Pteroplatea micrura, a
closely allied form, into the mouth, stomach and intestine.
Since the Beaufort species likewise have the spiracles
wide open, it is fair to suppose that they too feed in the
same way. This fluid, somewhat creamy in appearance,
was greasy to the touch, and readily coagulated When
put into preserving fluids like formalin. I regret that no
T Alcock, A. W., ‘‘ Zoological Gleanings from the Royal Indian Marine
Survey Ship Investigator,’’ ‘‘Scientifie Memoirs by Medical Officers of the
Army India,’’ Part 12, 1901.
402 THE AMERICAN NATURALIST [ Vou. XLIV
particular microscopical examination of this ‘‘milk’’ was
made. These observations fully confirm those of Alcock’
on Indian Ocean rays in the ‘‘Investigator’’ expeditions.
They are necessarily incomplete, but it is the purpose of
the writer to make a careful study of the phenomenon of
viviparity in sharks and rays.
Lepisosteus osseus, the ‘‘shell gar’’ of the fishermen
(so called to distinguish it from the green gar, Tylosurus
marinus, formerly Belone longirostris), often comes down
from the swamps and upper reaches of Newport River
into the brackish water at and even below the Narrows.
In 1908 my fishermen caught several at Cross Rock.
Of these, three were thrown on the grated bottom of the
gasoline launch, and, with no further attention than hav-
ing an occasional drenching with a bucket of salt water
and being covered from the sun’s rays by the corner of
an old sail, were brought to the laboratory. Here they
were put in a large tank of fresh water, which was aerated
only semi-oceasionally by a jet from a pet-cock. As a re-
sult of this severe experience, one of the fish died. How-
ever, the other two survived, though their pectoral and
caudal fins were badly split and were congested with
blood as a result of their threshing around on the floor
of the boat during the journey of more than an hour from
the fishing ground to the laboratory. Further, in a short
time the fins of the living fish became much worn by
contact with the sealing paint of the tank.
These two gars came safely through the winter of
1908-09, thanks to the care given them by the laboratory
men under the direction of the superintendent of the sta-
tion, Mr. Henry D. Aller. On my return to Beaufort on
May 26, 1909, I found that the fish had completely re-
generated their fins and that these were in as good phys-
ical condition as the day, ten months before, when the
gars were taken out of the bunt of the seine. However,
the larger of the two had the body curved in a curious
very flat S, which led me to think that it had suffered
some injury resulting in deformity. On June 4 this crook
had disappeared and the fish seemed to be perfectly
= ‘Alcock, A. W., op. cit.; ‘A Naturalist on Indian Seas,’’ 1902.
No. 523] NOTES ON BEAUFORT FISHES 403
normal. Later in the day my attention was called by
one of the laboratory men to some spawn floating near
the bottom of the tank. This was examined and found to
have a greenish color, and undoubtedly was the eggs of
one of the gars, presumably the larger. The crook in
the body of this fish was probably the result of an effort
on her part to rid herself of the eggs without the aid of
the sexual excitement engendered by the presence and
activity of a male as noted by Dean.? The eggs had
gone bad—strong evidence that the smaller fish was also
a female. When I left Beaufort, at the end of the first
week in July, the fish were in prime condition.
Although the water in the tank (size 3 feet by 8) in
which the fish were confined, was not more than six inches
deep and was aerated only semi-occasionally, the fish did
not seem to suffer, thanks to their vascularized air blad-
ders. I watched these gars at irregular but fairly frequent
intervals during my six weeks’ stay, and noticed that the
larger fish seldom came to the surface for air, but that
one was quite sure in a few minutes’ watching to see the
smaller do so. Certain preliminary symptoms always
preceded this action: the fish would swim around slowly
but uneasily, would shake its head from side to side,
would raise its snout nearly to the surface of the water
and then sink down; finally with almost imperceptible
rapidity the snout would be thrust out of the water and
the jaws would open and shut with a convulsive snap;
then, as the fish slowly sank to the bottom of the tank,
the gill covers would expand and one or two large bubbles
of air would escape from under each operculum.
The fish were fed simply by putting into the tank live
minnows, chiefly Fundulus. These seemed much fright-
ened and would huddle in a corner of the tank as far
from the gars as possible. In feeding, a gar would
slowly swim behind a Fundulus, make a sudden dash,
and seize it crosswise in its long toothed jaw. Then ele-
vating its head, possibly out of water, with a quick jerk
the gar would catch the fish head first and speedily
swallow it.
° Dean, Bashford, ‘‘The Early Development of Garpike and Sturgeon,’’
96
>
Journal of Morphology, Vol. 11, 1895-96.
ON THE EFFECT OF EXTERNAL CONDITIONS
ON THE REPRODUCTION OF DAPHNIA!
Dr. J. F. MeCLENDON
CORNELL MEDICAL COLLEGE
Since in the great majority of organisms only the
germ cells are capable of reproducing the entire indi-
vidual, the question as to what differences exist between
the germ and body cells, and how they arise, is of gen-
eral interest. Therefore any change of conditions which
affects the germ cells or their relation to the body cells
deserves special study. In Daphnia external conditions
not only affect the relation of the germ cells to the body
cells, but they affect the egg cells in such a manner as to
determine whether they do or do not need fertilization.
The purpose of the present paper is not merely to add
the results of my experiments to those of other investi-
gators, but to tentatively arrange the available data
under a general working hypothesis in the hope that
some more direct method of investigating the relation
of the germ and body cells be devised.
Last spring (March 10) I began experiments on the
effects of environment on Daphnia pulex, De Geer, with-
out knowing that Woltereck was working on the same
line. The material came from a small pool investigated
by Dr. W. C. Curtis and containing a single strain of
this and no other species of Daphnia. For the first few
weeks some ice remained on the pool and the tempera-
ture did not much exceed 4° C.; after this it rose steadily
to about 20° by the end of May. Specimens from the
pool were examined at intervals as a control on the ex-
periments.?
' From the Zoological Laboratory of the University of Missouri and the
i ae Laboratory of Cornell University Medical College, New York
-2 When the daphnids were crowded in dishes of the same pool water they
soon began to die, owing to the accumulation of their excretions. When
404
No. 523] REPRODUCTION OF DAPHNIA 405
EFFECT oF ENVIRONMENT ON DIFFERENTIAL GRowTH
By differential growth I mean the unequal growth of
different parts, viz., the germ and body cells. Only
parthenogenetic females were used, and each was kept
separately in the same quantity of water. All measure-
ments were made at sexual maturity, 7. e., when the
first eggs appeared in the brood pouch. Warren? found
that under uniform conditions there was a slight varia-
bility, but Woltereck showed that these fluctuating varia-
tions were very small, though he did find mutations as
rare occurrences.
Nutrition.—I had in the laboratory a pure culture of
a unicellular green alga which the daphnids ate readily.
This alga did not remain entirely suspended in the water,
but as the daphnids fed on the bottom as well as while
swimming, and stirred up the alge, it can not be said
that most of the food was out of their reach.
Those with a superabundance of food were larger at
sexual maturity and had a shorter spine than those with
insufficient food, and conversely. The smaller size and
longer spine of the starved daphnids are characteristic
of immature stages.
Temperature—Three sets of experiments were
transferred suddenly to artesian tap water many died, though with a
Aaa change all lived. The genes of the tap water was as follows:
Ca, .148 X 10 molecular; Mg, .1 X 10“ molecular; CO,, .045 X 10 molec-
ular; SO,, .146 x 10° saclpwalairs Cl, .055 X 10° molecular. Besides these
were very small quantities of silica, clay, iron, ammonia and nitrates, and
molecular PEE of certain salts. The toxicity of cations increased as
follows: NA<1/2 Ca<K, and of anions: Cl<1/2 80.< HOO, <1/2 HPO,.
But as K became toxic only on 1/100 and HPO, on 1/500 molecular concen-
tration there must be other toxic substances than salts in the water. The
earbon dioxide in the water killed crayfish and was probably the most toxic
— to the daphnids.
‘t An Paes rvation on Inheritance in Parthenogenesis,’’ Pros. Roy. Soe.
London, 1899, LXV, and ‘‘On the Reactions of Daphnia magna to certain
ieee in mieie; ’? Quart. Jour. Micr. Sc., 1900.
406 THE AMERICAN NATURALIST [ Vou. XLIV
started: at 4-10°, 19-20° and 29-31° C. The results
were as follows:
Ratio of Average Spine| Time from Hatching
Renae ey bene |Length to Body Length.| to Bernal Maturity.
4-10° 22 0.24 35 days
19-21° 20 0.25 sE. E
29-31° he diy 0.27 es
1 unit = 3, millimeters.
All were given a surplus of food daily. It may be
observed that a higher temperature has the same effect
as insufficient food.
Salts.—Since salts have such a marked effect on the
development of marine and some fresh-water animals,
I placed daphnids in the strongest solutions of various
salts that they would live in (without acclimatization).
The effects in two months (four generations) were un-
noticeable.
Light.—Cultures were kept in the dark and in diffuse
and direct sunlight, but no effect was observed.
A number of observers have recorded season-poly-
morphism in daphnids. Wesenberg-Lund?* pointed out
that when the specific gravity and consequent buoyancy
of the water decreased—by heat in summer—the body
of the daphnids became smaller or were provided with
outgrowths, so as to offer a greater resistance to sinking.
Wolfgang Ostwald® produced, all at the same time, the
forms that occurred in nature at different seasons, by
varying the temperature. He emphasized the fact that
rise in temperature lowered the internal viscosity of the
water. He found that in the warm cultures the daphnids
often became productive at an undeveloped stage and,
as is true generally, reproduction retarded body growth.
***Ueber das Abhingigkeitsverhiltnis zwischen den Bau der Plankton-
organismen und den specifischen Gewicht des Siisswassers,’’ Biol. Centlb.,
1900, XX, pp. 606-619, 644-656, and ‘‘Studier over de Danske séers
Een, ’ Copenhagen, 1904
‘* Experimentelle Ginga über den Saisonpolymorphismus bei
Daphniden,’’ Archiv f. Entwicklungsmech. d. Organismen, 1904, XVII, .
p. 415.
No. 523] REPRODUCTION OF DAPHNIA 407
Woltereck® maintains that Ostwald’s results were due
to the fact that at a higher temperature the daphnids
- need more food. Woltereck caused decrease in body
length both by starving and by increasing the tempera-
ture, but the latter was not effective with an optimum
supply of food. He found that more food than the
optimum produced effects similar to starving. Raising
the internal viscosity of the water by adding quince gum
produced no effect. He showed that though feeding in-
fluenced the differential growth, there was a cyclical
tendency for this to vary, viz., season-polymorphism.
However, the effects of prolonged abundant feeding were
inherited to some degree.
One might interpret these results in different ways.
It is known that the temperature coefficients for various
chemical reactions are slightly different. Possibly the
mean of the temperature coefficients for the processes
in the development of the reproductive organs is higher
than the same for the body wall, and at a higher tem-
perature the germ cells would develop faster. However,
under adverse conditions the ‘‘affinity’’ of the repro-
ductive organs for nutriment is greater than that of the
rest of the body, so with deficient food the body wall is
retarded more than the germ cells in development. The
higher temperature may be considered an adverse condi-
tion since the mortality is greater. In this way starv-
ing has the same effect as a higher temperature.
Langerhans? found that accumulation of excretions
caused shortening of the spine in daphnids. I do not
know what relation this bears to the above results.
®<¢Teber naturliche und kunstliche Varietitenbildung béi Daphniden,’’
Verh. Deutsch. Zool. Gesell., 1908, p. 234; and ‘‘ Weitere experimentelle
Untersuchungen über Artveranderung, speziell über das Wesen quantitativer
Artunterschiede bei Daphniden,’’ ibid., 1909, p. 110. |
*<<Ueber experimentelle Untersuchungen zu Fragen der Fortpflanzung,
Variation und Vererbung bei Daphniden,’’ Verh. Deutsch. Zool. Gesell.,
1909, p. 281.
408 THE AMERICAN NATURALIST [ Vou. XLIV
EFFECT oF ENVIRONMENT ON THE LIFE CycLE
In most species of daphnids, generations of partheno-
genetic females alternate with generations of males and
females which produce eggs that must be fertilized, and
either frozen, dried or kept a long time before they will
develop (resting or ‘‘winter’’ eggs). In different
species the number of successive parthenogenetic gen-
erations varies. In some all are, and in some none are,
parthenogenetic.
I found that heat hastened the appearance of sexual
forms, as did starving or the accumulation of excretory
products. All of these factors might be combined in the
drying up of a pond, as heat would aid in drying, and
drying would concentrate the daphnids and their ex-
cretions, and concentration of the daphnids would cause
them to eat up the alge faster than they could multiply.
However, by keeping the culture cold, fresh or well-fed,
or all combined, I could delay but not prevent the ap-
pearance of sexual forms.
Kurz’ said the drying up of the water caused the ap-
pearance of sexual forms, and Schmankewitz? suggested
that it was the increase in salts. Weismann’ tested
both of these hypotheses and concluded that they were
wrong. He also tried the effect of food and tempera-
ture, with varying results. He concluded that the life
cycle was fixed for each species and variety. Issako-
witz" concluded that cold favored the appearance of
sexual forms and warmth favored the parthenogenetic.
Also, hunger favored the appearance of sexual forms
and abundant food the parthenogenetic. It may be that
cold retarded multiplication of the food plant or the
$í Dodekas neuer Cladoceren nebst einer kurzen übersicht der Cladoceren-
fauna Bohmens,’’ Sitz. Ber. math. naturw. Wien, 1875.
***Zur Kenntnis des Einflusses der ausseren Lebensbedingungen auf die
Organisation der Tiere,’’ Zeit. wiss. Zool., 1877, XXIX.
<< Beiträge zur Naturgeschichte der Depiets, VII,’’ Zeits. wiss.
Zool., XXXIII, p. 111.
n 1 Gauablaslasaaacabide Ursachen bei den Daphniden,’’ Biol. Cen-
tralb., 1909, XXV, pp. 529-536
No. 523] REPRODUCTION OF DAPHNIA 409
movements of the daphnids so that they did not keep
the alge stirred up in the water sufficiently to get at
them. The parthenogenetic egg arises from four cells,
but a large number of cells enter into the composi-
tion of the fertilizable egg. If the latter egg is not
fertilized it is absorbed and, as Issakowitsch noted, fur-
nishes food for the development of parthenogenetic
eggs.
Woltereck!? found that starving hastened the appear-
ance of sexual reproduction, but a concentration of food
above the optimum produced results similar to starving.
He found, as Weismann maintained, a cyclical tendency
toward the alternation of sexual and parthenogenet:¢
generations which, contrary to Weismann, was tempo-
rarily influenced by nutrition, and the effects of constant
nutrition over a long period was inherited to some ex-
tent.
Langerhans'* found that the accumulation of excre-
tions caused the decrease in numbers of parthenogenetic
females in the autumn and thinks that the appearance
of sexual forms is due to the same cause.
The life cycle of a daphnid is, therefore, an hereditary
tendency, but can be influenced by nutrition and probably
by temperature and the accumulation of excretions.
Nutrition is the most important factor, and former ex-
periments on the effect of temperature and the drying
up of the water were complicated by secondary effects
on concentration of food and excretory products.
Discussion of Results—Two views might be held as
to the origin of the differences between the germ and
body cells: the differences might be the result of differ-
ence in position in the embryo, or of unequal mitoses.
In the parasitic copepods I found the primary germ cell
to arise by an unequal mitosis at the fifth cleavage of
the egg. The germ cell when first formed is one thirty-
second of the total number of cells, but owing to the more
2 Loe. cit.
8 Loc cit.
410 THE AMERICAN NATURALIST [ Vou. XLIV
rapid division of the body cells this ratio decreases. In
fact the chief difference between the yolk-free body cells
and the (yolk-free) germ cells is the slow rate of division
of the latter. Finally, the eggs will not divide at all un-
less specially stimulated, by fertilization. The question
now arises: what causes the cell to divide. Sacks found
that plant cells divide when they have reached a certain
size. This rule has been extended to animals, and the
final size of the cell found to be determined by the ratio
of nucleus to cytoplasm. This rule may apply to the
germ cells, since it appears that after the egg cell, pri-
mary oocyte, reaches a certain size any additional food
absorbed does not cause growth of the protoplasm, but
is precipitated as yolk.
If the egg is properly stimulated, rapid growth of
protoplasm and cell divisions follow. From the study
of artificial parthenogenesis it appears probable that
stimuli which lead to development of the egg increases
the permeability of its plasma membrane. If this be
true we may say that the germ cells are distinguished
by the fact that their plasma membranes are poorly
permeable and retard those reactions between the cell
contents and environment which lead to growth and cell
division. In other words, the optimum intensity of stim-
ulation toward growth and division is higher for the
germ cells than for the body cells.
This difference is probably due to a difference in the
colloids of the cell, which in animals could be explained
as the result of an unequal mitosis. This explanation
may be modified so as to apply to plants. Klebs has
shown that those conditions which are adverse to vege-
tative growth of plants (too strong stimuli?) call forth
flowers. Perhaps there are slight differences in the
sensitiveness of plant cells to stimuli, and as the stimuli
increase, those initially least sensitive cells acquire
further immunity to the stimulus, whereas those initially
more sensitive cells are overstimulated and weakened.
‘Thus the difference between germ and body cells is grad-
No. 523] REPRODUCTION OF DAPHNIA 411
ually acquired. The Malpighian layer of the skin may
be stimulated to proliferate more rapidly, but if the
stimuli are too strong the growth will be retarded instead
of increased. On gradually increasing the stimulus im-
munity to it may be acquired.
To apply this hypothesis to the daphnids: conditions
which are adverse to the growth of the body cells, such
as extremes of temperature (viz., high temperatures) or
of concentration of excretory products, or disorded nu-
trition, either fail to retard the development of the germ
cells or stimulate their development, so that in either
ease the daphnid becomes sexually mature at a less de-
veloped stage. Under the less extreme conditions the
eggs develop on receiving the slight stimulus incident to
their transfer to the brood pouch, but under the more
extreme conditions those eggs which develop at all must
be stimulated by fertilization before they develop.
These two types of eggs may perhaps develop from two
kinds of cells, or the sexual egg may arise from the same
kind of cell producing the parthenogenetic egg by ac-
quiring an immunity to slight stimuli. Whereas more
than one cell goes to make up a single egg; only one
nucleus is retained, and it may be said that one cell is the
egg cell and the remainder furnish its food.
ARE FLUCTUATIONS INHERITED?!
DR. HARRY H. LOVE
CORNELL UNIVERSITY
Tue object of this paper is to present certain facts in
regard to the inheritance of fluctuations which have been
obtained from a study of the common garden pea (Pisum
sativum). While an experiment was being conducted
to study the effect of fertility upon the fluctuating varia-
bility of certain characters, data were also obtained to
show to what extent these fluctuating characters are
inherited. ‘The peas used were a mixed population and
not a pure line, and had not been selected for any partic-
ular character when the experiment was started.
The belief has long been held that the improvement
of animals or plants could be obtained by selecting from
the best individuals, or those possessing to the greatest
degree the quality desired.
The fact is that at present most of our agricultural
breeding and improvement is based upon this belief and
this is the method which is most generally followed in
practical breeding. This view held sway from the time
of the earliest breeders until the appearance of the Muta-
` tion Theory by DeVries. It was first stated scientifically
y Darwin in his ‘‘Origin of Species,’’ for Darwin, after
a study of the evidence accumulated, was convinced that
the improved breeds had been obtained in this manner.
He says:
We ean not suppose that all the breeds were suddenly produced as
perfect and as useful as we now see them; indeed, in many cases we
know that this has not been their history. The key is man’s power of
accumulative selection: nature gives successive variations; man adds
_ them up in certain directions useful to him. In this sense he may be
said to have made for himself useful breeds.’
*Contribution VI, Laboratory Experimental Plant-breeding, Cornell
University. The writer expects to follow with a series of articles on the
oe _ same subject.
eee Tpit ot Species,”? Chapter 1, p. 35, Murray Edition.
os 412
No. 523] ARE FLUCTUATIONS INHERITED? 413
He further states:
If selection consisted merely in separating some very distinct variety,
and breeding from it, the principle would be so obvious as hardly to be
worth notice; but its importance consists in the great effect produced
by the accumulation in one direction, during successive generations, of
differences absolutely inappreciable by an pueden eye—differences
which I for one have vainly attempted to appreciate.
DeVries after much careful experimentation and study
of results of agricultural breeding (mainly the results
at Svalof and those of the German breeders) showed
that much of the improvement which has occurred was
not due to cumulative selection but must be explained in
some other manner.
In recent years much careful scientific work has been
done along this line to test the action of selection within
a pure line and in a mixed population.
The Svalöf Experiment Station has done much in prac-
tical plant-breeding to show that, with reference to the
cereals especially, the effect of selection went no further
than to isolate the pure lines, and when this was accom-
plished no further gain was made by selection.
ohannsen,* working with beans and Jennings® with
Paramecium, have arrived at the same general conclu-
sion which has been summed up by Pearl® as follows:
From a mixed “ general” population it is possible by a single selec-
tion to isolate pure strains (“ pure lines,” “ homozygote strains,” “ pure
races ”) which will breed true and not revert to the mean of the gen-
eral population from which they were isolated, regar rdless of whether
Continued breeding from the extreme individuals of such a pure strain
(“ fluctuating ” variants) does not change the mean of that strain.
From these considerations it follows that it will be difficult or impossible |
to make any definite and permanent change in the mean of a general
population simply and solely by continued selection of extreme indi-
3 Loe. cit., p. 36.
+í Uber Erblichkeit in Populationen und in reinen TN ” Jena, 1903.
5<‘ Heredity, Variation and Evolution in Protozoa, II,’’ Heredity and
Variation of Size and Form in Paramecium with Studies of Growth, En-
vironmental Action and Selection, Proc. Amer. Phil. Soc., Vol. XVI, pp.
E 1908.
‘‘Is there a Cumulative Effect of Section?’’ Abstammungs- und Verer.
RE Pe 2, 1909, H. 4
414 THE AMERICAN NATURALIST [Vou. XLIV
viduals, because in the vast majority of cases such individuals will be
extreme fluctuating variants rather than mutants.
Jennings’ states in his paper that ‘‘Systematic and
continued selection is without effect in a pure race, and
in a mixture of races its effect consists in agen the
existing races, not in producing anything new.” And
concludes® that ‘‘Until some one can show that selection
is effective within pure lines it is only a statement of
fact to say that all the experimental evidence we have
is against this.”
Recently Pearl? has brought forth a very noteworthy
contribution in this line. His evidence is based upon
the work which is being done at the Maine Agricultural
Experiment Station to determine the effect of selection
on fecundity and the inheritance of fecundity in poultry.
His conclusions may be summed up as follows:
Selection for high egg production carried on for nine. consecutive
years did not lead to any increase in the average production of the
flocks.
The present data give no evidence that there is a sensible correlation
between mother and daughter in respect to egg production, or tha
egg-producing ability (fecundity) is sensibly inherited.
In this experiment the daughters of “ 200-egg” hens did not exhibit,
when kept under the same environmental conditions, such high average
egg production as did pullets of the same age which were the daughters
of birds whose production was less than 200 eggs per year.
Professor Waugh,’ of the Massachusetts Agricultural
Experiment Station, has been making some studies of
the variation of peas and the inheritance of the differ-
ent fluctuating characters. He has found that the coefli-
cients of heredity for the different characters are very
low and are not very significant in the case of any one
character. The two characters, length of vine and num-
ber of pods per vine, show a coefficient of heredity of
-170 and .158, respectively. At the same time he found
that there were certain lines that did reproduce their
characters to an appreciable extent, which is along the
: *<¢Heredity and Variation in Simplest Organisms,’’? Amer. NAT., June,
: * Twenty-first Amn. Rept. Mass. Agr. Exp. Sta., Part IT.
415
ARE FLUCTUATIONS INHERITED?
No. 523]
Pett
H:
i]
{|
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a
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a cers mee mare a
A
i HEES 3 [a
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PEETER nanas y
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reneuee=
FELGE
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ma a BH H
SeeRUESS
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ESSEN
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Diagram showing the relation between parents and offspring in
regard to number of internodes-on the untreated plot.
sents the parents and the solid line the offspring.
The broken line repre-
EER TESI
S38 seese
Shee? IRERE! J
Fig. 2. Diagram showing the relation between parents and offspring in
regard to number of internodes on the treated plot.
the parents and the solid line the offspring.
The broken line represents
line of other studies dealing with pure lines which have
been reported.
The evidence which the writer here presents is not
based upon large enough numbers to be conclusive
agaye
wt
. =
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the
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of a practical experiment to develop a st
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The number.
in
itself, but it is certainly suggestive and adds to the facts
already brought together.
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of each plant was known.
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[Vou. XLIV
THE AMERICAN NATURALIST
461
EE ooren
M i ig = ze ESP pees gF ESE
fa 5 | FETTY REETH [>] A b mM = rab) M = mM © $ ©
è D : Wun Be = A F go z [oF HEO = te a
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m i ea a oa Hd asl eA | Za 2 g a 2 O $ 3] fæ Aon- > o
Bl] aas oa Me! gaa SSSR | SAS Sa y ae
Li ue o eee SpesePeese oo eh
Sago EHH E aoo i Bo E A e E, = :
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A Z g i LHH A gs D ZB 3 + =u iz 43 H ad E TA A.
Eg E Aa see ae.
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No. 523] ARE FLUCTUATIONS INHERITED? 417
et eat)
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Fie. 5. Diagram showing the iene between parents and offspring in
regard to number of peas on the tr a plot. The broken line represents the
parents and the solid line the offsprin
Regression tables were made for several characters
obtained from the plants studied. Such characters as,
height of plant, number of internodes, number of pods,
number of peas and yield of seed were observed. The
results of these calculations are shown in Table I.
TABLE I
Coefficients of Heredit
Character Ordinary Soi] Plot Fertilized Plot
Number of internodes ............... 027 + .064 — .050 + .067
Number pods per plant <.........s..+ — .235 + .061 012 + .067
Number peas p Plane oho eeen — .152 + .063 —. + .067
FLORES of DUE s Cae on — .191 + .062 -014 + .067
Yield of plant va in grama) so — .100 + .0 -001 + .067
We see that the coefficients of heredity are very low
and some of them are even negative. This shows that
as far as this data is concerned these fluctuating char-
acters do not follow the law of regression to any appre-
ciable extent. No emphasis should be placed upon the
fact that some of these coefficients are negative, but the
point is that they are not positive to any noticeable de-
gree. The charts (Figs. 1-9) show in a graphic manner
[ Vou. XLIV
THE AMERICAN NATURALIST
418
ie Oo OH AE
pmen o sn onog = soo Oe Le \
mem (3s BERESSRSESHSRESE B88
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i aerate a Haca. of eo gB ome 5 Sy: as
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il Q m 4a 0O o mM . Ps D
— E Siesta, eceas ess sgked &
H H = —t2oHh gts g for e= SARAR
H amer ssi Bg eons & woe OS he eee TE
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a HH ad go $ + ë mM wo A.
H te B's oR zd zs Fhe 2 agsoiw nS
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Beit e3 Sgeres yet aos tek bee
HEIEN TERI H ac eae Soh bH E a paadal
men E HEHH m =) = bù Q . m ® Ra 4 TE, =| g [æ] B = o
H i - wss = S o 2s SSp AES APA oF ae ac :
uh ea
H HRS a4? Soo CPS S260 S59. & : o
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AG ae 2S om Sa © = gaggoó
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419
?
ARE FLUCTUATIONS INHERITED
No. 523]
in
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HH pE i gs g7385 dp
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a a: i ge 69 E sig
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THE AMERICAN NATURALIST
420
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No. 523] ARE FLUCTUATIONS INHERITED? 421
second or middle third, or those near the mean, and the
third third, or those in which the average for the parents
was the highest. The average was obtained for the dif-
ferent characters in the offspring produced from these
different lots of parents and the results tabulated and
shown in Table III.
TABLE III
AVERAGES FOR THE DIFFERENT CHARACTERS
First Third. Second Third. Third Third.
Ch ; ey eee ee
PE Parent. off- Parent. off- Parent. off-
spring. spring. spring.
Height, untreated ........ .. 28.7 64.1 36.8 65.4 48. 59.6
** treated 75.1 46.6 77.1 56.8 77.5
Internodes, untreated .......| 12.1 16.2 14.1 16.8 16.4 16.4
me re 12.1 iyavi 14.6 18.3 bg 17.8
Number pods, untreated 3.3 2.9 3.1 ‘4.4 2.8
ss " treated.....<. ok 3.9 4.4 4.1 Ti 4.0
Number peas, untreated 5.6 5.6 8.8 5.8 14.2 4.7
s ‘oo obreated ac, 8.9 8.5 15. 7.3 25.5 8.8
Yield, untreated.............. 1.311] 1.044} 2.100 .972 | 3.343 .889
ae | : 1.941 | 1.453 | 3.335) 1.453 | 5.688| 1.488
We see that there is no general increase for the value
of the different characters as we pass from the lower
half to the upper half, or from the lower third to the
middle or upper third. In some instances there is an
increase, in others a decrease. That is, the individuals
resulting from the parents above the mean do not possess
the character to any greater degree than those resulting
from parents below the mean. We see then that these
data answer the question in the negative; or to take a
concrete case, the number of peas per plant on the un-
treated plot show that plants resulting from the upper
half of the parents do not produce any more peas per
plant than those coming from the lower half. The re-
sults are as follows:
Average of Parents Average of Offspring
6.4 5.9
12.7 4.8
The two tables show very clearly that as far as this
data are concerned, there is no difference in the offspring
resulting from high or low averaging parents.
—
422 THE AMERICAN NATURALIST [ Vou. XLIV
As peas are self-fertilized, it will be of interest to
note some results obtained with a cross-fertilized crop.
The writer has obtained data from selection experiments
in corn which are very interesting in this connection.
While selecting for yield and earliness data have been
obtained which tend to show that corn is not different
from peas and that in general fluctuations are not in-
herited, but that certain individuals reproduce to a high
degree. The results obtained with yield are shown in
the following table.
TABLE IV
Average Yield of Parents Average Yield of Offspring
Plot E ea sea 46.6 Ibs. per row 43.0 Ibs. per row
PIE sa ace. 3 es 52.5 Ibs. per row 44.8 lbs. per row
PION Breese ene tas 27.2 lbs. per row 81.5 lbs. per row
fg ee Beek ore ee 34.1 lbs. per row 76.2 lbs. per row
While making these studies the effect of the size of
seed planted on the offspring was determined. In plant-
ing the second generation plants, unfortunately, the seeds
were not weighed, but an average seed from each parent
was taken and planted. The chances are that by select-
ing in this manner an average sized seed would be ob-
tained, and since the average weight seed for each parent
plant is known, it seems fair to assume that the seed
planted approached the average weight of seed. Regres-
sion tables were arranged for the two plots in which the
height of plant for the offspring was correlated with the
average weight of seed for the parent plants. These
tables show that as the average weight of seed planted
increases, the height or size of the resulting plant also
increases. Although the coefficient is not high in either
ease, yet it is higher on each of the plots taken than that
determined for any character. This seems to show that
the size of seed, regardless of the plant from which it
came, has more influence on the offspring than the parent
plant itself. The coefficient is .276 + .059 for the un-
treated plot and .139 + .066 for the treated plot.
Waldron? has shown that large (heavy) seed in oats
ae Suggestion Regarding a and Light Seed Grain,’’ AMER. NAT.,
: a4 2 XLIV, TOT 1910.
No. 523] ARE FLUCTUATIONS INHERITED? . 423
comes from the shorter culms and suggests that in select-
ing large seed for planting we are selecting from small
plants. This may be true. The writer finds that the
average weight of seed in peas decreases with the height
of plant, which corresponds to the results obtained by
Waldron. On the other hand, when these are planted
the larger seed, although coming from smaller (shorter)
plants, produced larger plants than smaller seed which
came from the large plants.
The foregoing results then indicate that there is not
enough evidence in favor of the inheritance of fluctua-
tions caused by environment to form a practical work-
ing basis. That is, by selecting out the individual plants
which give an exceptionally high yield we would not
obtain any higher yielding individuals than from a selec-
tion taken at random.
We find then that we a given a definite answer to
the question which is the title of this paper.
While such statements do not accord with those who
place their faith in cumulative selection, yet it is only
a statement of fact as shown by an analysis of such
data as are here brought together.
These results accord very closely with those stated by
Pearl and we can agree with a statement made by him
which is as follows:
Altogether much evidence is accumulating from widely different
sources to show that simple selection of superior individuals as breeders
can not alone be depended upon to insure definite or continued im-
provement in a strain. Some improvement may possibly follow this
method of breeding at the very start but the limits both in time and
amount are very quickly reached.
The rapidly accumulating facts in this respect bring
us to face a different view of the value of selection. The
testing of individuals to learn their power to reproduce
their characters must be done just the same but a differ-
ent interpretation must be given the results obtained.
Unless further studies produce different results, we
can say from the facts at hand that there is no evidence
to show that a basis exists for cumulative selection.
INHERITANCE IN POTATOES
PROFESSOR EDWARD M. EAST
HARVARD UNIVERSITY.
A stupy of the behavior of certain plant characters
in inheritance formed part of an investigation into the
factors connected with the improvement of the common
potato as a commercial crop, begun at the Connecticut
Agricultural Experiment Station in 1906. This work
was really a continuation of investigations made by the
writer at the University of Illinois from 1902 to 1905,
along broader and somewhat different lines. In 1908"
the many disheartening difficulties attending hybridiza-
tion were discussed, but it was shown to be possible to
overcome several of the obstacles by proper treatment.
The conclusions drawn at that time have not been
changed by further experience, but the hindrances caused
by external conditions not under control have been so
great that the work has been discontinued. For exam-
ple, in 1908 a prolonged drought at the time the fruits
were forming, caused one hundred and fifty cross- and
self-pollinated seed-berries to drop off while yet too im-
mature for the seed to germinate. Not a single hand-
pollinated flower matured its fruit.
Recently, a part of the pedigree records were lost in a
fire which destroyed one of the buildings of the Connecti-
eut Agricultural Experiment Station. For these reasons
the data reported here do not represent fairly the
amount of work done upon the subject, for the actual
number of plants under observation was considerably
larger than the figures reported. The complete figures
had been studied with some care before the loss of the
records, and it is thought that the remaining records are
a fair sample of the whole.
The records contain observations on only one genera-
1Some essential points in potato breeding. Biennial Report, Conn.
Agr. Exp. Station, 1907-1908, 429-447, 1908.
424
No. 523] INHERITANCE IN POTATOES 425
tion of plants, together with the characters possessed
by their parents. I have endeavored to find what char-
acters were possessed by the parents of the varieties used
in crossing but have found no trustworthy data. The fol-
lowing conclusions, therefore, are tentative. Nothing is
known about the behavior of the characters when ex-
tracted. The data show that certain characters segre-
gate, they give some evidence as to dominance and re-
cessiveness, but they do not show the exact behavior of
the Mendelian factors concerned, under different com-
binations.
COLOR IN THE PLANT STEM
Many varieties have a purple anthocyan sap color.
which gives the plant stem a dark appearance quite dis-
tinct from the clear green stems of the varieties in
which it is absent. The color is variable in amount in
different varieties. In some it extends throughout the
petioles and petiolules; in others it can only be detected
on the stems of the young seedling. My counts were
made on seedlings about four inches high.
The color is evidently of the same nature as that
found in many other cultivated plants. Its widespread
occurrence and seeming uselessness in the plant’s
economy would place it in the category of typical varie-
tal characters in the sense used by De Vries. It forms
a single allelomorphic pair with its absence.
One purple-stemmed variety selfed gave all purple-
stemmed progeny. Four purple varieties selfed, each
showed segregation into two distinct classes, purple and
non-purple. Fifty-four purple plants and seventeen
non-purple plants were obtained. (These figures as well
as those that follow are the records saved from the fire.)
In each of these cases we may take it that the parent
plants were heterozygous for the purple color, and ap-
proximated the simple three to one Mendelian ratio when
self-pollinated. Four green-stemmed varieties were
also selfed, and produced nothing but green-stemmed
progeny.
-—_
426 THE AMERICAN NATURALIST [Vou. XLIV
One of these pure green-stemmed varieties was
crossed on one of the heterozygous purples, and thirteen
seedlings were obtained. Six plants were purple-
stemmed and seven were green-stemmed. This result is
what would be expected when crossing DR X R.
COLOR IN THE FLOWERS
All potato flowers have a ray of yellow extending from
the limb of the corolla toward the apex of each lobe.
The remainder of the corolla is either white or purple.
There is wide zygotic (in potatoes, therefore, varietal)
variation in the intensity of the purple sap color, but the
flowers should probably be classed as either purple or
white. The fact that the variety color, whether light or
dark, remains true when propagated asexually, does
not necessitate more than one Mendelian pair. It is
undoubtedly a quantitative difference in the same pig-
ment which is kept constant by the asexual method.
Why somatic cell divisions should reproduce a color
shade so exactly, while sexual reproduction gives rise to
varying shades is unknown. It is the more peculiar
since in animals visible division of the chromatin ap-
pears to be much more accurate in the sexual cells than
in the somatic cells. The somatic cell appears to have
the power of developing and of regenerating only the
quantity of color originally apportioned to it, except on
the rare occasions when all of the potential color activ-
ity goes to one daughter cell and the other is left with-
out it. When this occurs, branches resulting from the
descendants of the second cell are ‘‘sports’’ or ‘‘bud-
variations’’ in which the original character is lost.
Only two varieties of potatoes with flowers other than
purple or white have been noticed. The variety Hol-
land fleur de June has blossoms which are decidedly yel-
low. Several attempts to self this variety and to cross
it with other varieties failed. One other variety, a
nameless seedling of unknown origin, possessed a true
blue flower. No admixture of red which would give it a
No. 523] INHERITANCE IN POTATOES 427
purple tinge could be detected. Even this color, how-
ever, may be of the same nature as the purple color, the
difference being in the completeness of the reaction
forming the blue dye. It will be remembered that lit-
mus reacts in this manner. Several cross-pollinated
and several self-pollinated fruits were obtained from
this variety, but none of the seedlings had flowered in
1909, the second year of their growth.
The seedlings of the potato are very slow to flower in
a New England environment, and but few flower records
were obtained among several hundred plants. One
selfed variety with purple flowers gave progeny all with
colored flowers. Three selfed varieties with purple
flowers gave both purple and white flowers: the total
number of seedlings that flowered was nineteen, of which
fourteen were purple-flowered and five were white-flow-
ered. Three selfed white-flowered varieties gave noth-
ing but white-flowered progeny.
Since three white-flowered varieties gave nothing but
white flowers and three out of four colored varieties
showed a hybrid condition with segregation of color, the
purple is probably dominant to its absence. Color and
no color is probably a single Mendelian pair, but this
can not be stated with certainty from such meager data.
COLOR IN THE TUBERS
Potato tubers, when colored,? are either purple or red.
In both eases the color may extend over the entire tuber
or may be limited in extent. No definite mosaic pattern
is formed when the color is limited, but the splashes of
color are restricted to pretty definite areas. It is prob-
ably due to a separate Mendelian factor, for the mosaic
varieties and the self-colored varieties are distinct.
Tuber color varies quantitatively more than flower color.
Many varieties show no color in the skin, and can be
classified only by examining the young shoots when the
2 Colorless skins may vary from white to dark brown in different varie- —
ties. This is entirely due to their possessing corky layers of various
thicknesses.
ed
428 THE AMERICAN NATURALIST [ Vou. XLIV
latter are about half an inch in length. The progeny of
such varieties belong to the same classes as the progeny
of self-colored varieties. They give fewer self-colored
seedlings, however, which may be due to the action of
one or more unknown heritable factors. I have not at-
tempted to separate the self-colored from those showing
color in the young shoots, but have classified both as
colored varieties.
The results of selfing varieties with different color
characters are as follows:
Selfed purples gave either all purples (one variety) ;
purples, reds and colorless (two varieties); or purples
and colorless (three varieties). Selfed reds gave either
all reds (two varieties), or reds and colorless (two
varieties). Selfed red varieties gave no purple progeny.
Three colorless varieties (that is, no color in either the
tuber skin or young shoots) were selfed, giving all color-
less progeny. ,
Without considering factors for limiting color, these
results seem to show that purple and red are separate
Mendelian units, each dominant to its absence, and that
purple is epistatic to red.
It is an interesting fact that although the purple vari-
eties and the red varieties are distinct color types with-
out intermediates and that mosaic varieties of each are
known, yet in no case has a mosaic variety appeared in
which splashes of the two colors are found. We may
conclude therefore that the two colors are formed by the
action of other factors upon the same chemical constit-
uent. If we assume that the red color is a lower form
of oxidation than the purple color and that they are pro-
duced by different oxidases R and P acting upon the
same substance C, the results obtained are explained, for
the presence of P would oxidize all of the stubstrate to
the purple color.
SHAPE oF TUBER
Potato tubers vary in shape from a length six times
the median diameter to a length about the same as the
No. 523] INHERITANCE IN POTATOES 429
median diameter. The varieties, the length of whose
tubers is not over one and one-quarter times the medium
diameter, I have called round. Two selfed round varie-
fies gave only round progeny. Twelve varieties with oval
tubers when selfed gave elongated, oval and round
progeny. The ratio of other types to round was about
nine to one. Either there is a series of factors for shape
with the round type as the final subtraction form, or
the oval types are heterozygotes of elongated and round.
The latter interpretation is more likely to be correct,
because oval types have been the popular market types
for many years and therefore been used as parents in
crosses.
DEPTH or Eves
Shallow buds or eyes are required for profitable com-
mercial varieties, yet from one fifteenth to one fourth
of the progeny of ten selfed varieties were deep-eyed
forms. Three selfed varieties gave no deep-eyed prog-
eny. No progeny of deep-eyed seedlings were obtained,
but it seems probable that this character is recessive to
shallow eye.
The writer is fully aware that these few observations
do not prove that the characters in which potato varie-
ties differ all segregate in Mendelian proportions after
crossing. A long series of crosses is necessary to an-
alyze correctly the behavior in inheritance of such char-
acters as shape. On the other hand, the color characters
` in stem, blossom and tuber are definite and discontinu-
ous, and are alternative in inheritance. The chaotic ap-
pearance of the progeny of our commercial potatoes is
only apparent. They readily fall into a simple classi-
fication and their exact behavior in inheritance could
be readily determined if it were not for the difficulties
attending successful crossing.
As the writer has previously stated,’ certain char-
acters pair with their own absence in crossing and these
Transmission of Variations in the Potato in Asexual
tion,’’? Biennial Report, Conn Agr. Exp. Sta. 1909-1910, 119-161, 1910.
430 THE AMERICAN NATURALIST [Vou. XLIV
character pairs are the ones affected when a somatic
mutation or bud variation occurs in asexual reproduc-
tion. Simple loss of the factor takes place. Segrega-
tion, therefore, takes place at other times than the
reduction of the chromosomes.
In a previous paper,‘ the writer analyzed the data
then extant concerning the hypothesis of degeneration
or ‘‘running out’’ of potato varieties. The conclusion
was that no degeneration due to continued asexual prop-
agation occurs. No data have been obtained which re-
fute this view, but the study of progeny of selfed potato
varieties has suggested an explanation of a certain
amount of diminution in yield after long-continued
asexual propagation. All commercial potato varieties
which have been selfed and their progeny grown, have
proved to be heterozygous in at least two characters.
It has been shown® that when maize biotypes are
crossed, the F, generation has greater vigor and gives
larger yields than the parents. It is a condition apart
from inheritance, and is probably due to the heterozy-
gous condition of certain characters in the germ cells.
It may be correlated with the actual mechanical opera-
tion of segregation. Since potato varieties are retained
in cultivation on the basis of yield and since those on
the market have been found to be heterozygous in many
of their characters, probably the same phenomenon is the
cause. May there not be a gradual loss of the stimulus
due to crossing through continued bud propagation,
so that the variety has only the vigor of one homozygous
in the same characters? The variety of course remains
heterozygous for those characters in which it was orig-
inally heterozygous, yet there may be a gradual decline
of the stimulus to cell division than it once possessed.
*A ‘“‘ Study of the Factors influencing the Improvement of the Potato,’’
ee Til. Agr. Exp. Sta., No. 127, 375-456, 1908.
, E. M., ‘‘The Distinction between Development and Heredity in
Inbreeding,” AMER. Nat., 43: 173-181, 1909.
SHORTER ARTICLES AND CORRESPONDENCE
THE AGE OF SPEED SIRES
In the May number of the Narurauist, Mr. Redfield makes
reply to the criticism of his theory which I made in the issue
of January of last year.
Recalling the interest evidenced by biologists when Mr. Red-
field’s theory appeared some years ago, and considering that no
one else has criticized his figures, I assume the question to still
be a proper one for discussion.
Mr. Redfield’s conception of acquired dynamic development
and the data he presented to show its inheritance, strongly sug-
gests the direct transmission of effects of use of the organs.
It is true that more than a majority of successful breeders of
trotting horses believe the results of use to be transmitted. A
settlement of the question is of no direct interest to horse breed-
ing interests. A change of opinion would not change their
practise. Selection and environment are the fundamental fac-
tors upon which their work is based. It is immaterial whether
they consider one or the other to be of greatest moment; both are
imperative. Mr. Redfield would say that the effect of the en-
vironment is transmitted. Selectionists would say that the
racing test as a feature of environment is an indispensable aid
to selection of good individuals and is the only real proof of
individual merit.
The fact that a few breeders who regard training as an aid
to selection have been as successful as any of the breeders who
think otherwise, goes to show that in the breeding of trotters,
practises of best breeders vary but little. They differ in their
soar of how the two factors exert their influence upon the
esults. This lack of agreement, while of no immediate import in
Bs breeding, because it bears upon a principle involved
is of primary interest in the scientific study of heredity.
In my contribution last year, I criticized Mr. Redfield’s —
only as they related to the age of sires. He assumes
development to be proportionate to the amount of racing ae
to the age.
431-
432 THE AMERICAN NATURALIST [Vor. XLIV
Mr. Redfield’s own words will explain the evidence from
which he argues for the value of age:
I said that I took one thousand registered stallions, alphabetically,
from the “ Index Digest” of the “ Register,” and calculated the ages of
their sires at the time when these registered stallions were foaled. From
these I determined that the average time between generations in the
male line was 10.43 years, which would give the average age of sires as
9.43 years at the time of service. I then said that, making all reason-
able allowances for errors, the average time between generations in the
male line might be set down as between 10 and 11 years, and that this
period might be used as a standard in testing the age part of the theory.
So far no one claims to have tested the accuracy of my calculation; no
one claims that the figures I gave were wrong; and no one has sai
that these figures can not properly be used as a standard; yet if I
am to be controverted, one of the first things to be done is to dispute
the accuracy of my standard.
I then took the entire list of 2.10 trotters as an appropriate class of
animals to be used in testing the inheritance of dynamic development,
and I calculated the ages of their male progenitors for four generations.
The number of animals involved was over five thousand and I gave the
average time between generations in the male line for the production
from the “ Register,” and my explanation of this remarkable difference
was that it indicated the inheritance of acquired dynamic development.
So far no one has disputed the accuracy of my computation and no one
has attempted to give any other explanation of such an unusual
divergence from the natural order of things.
My objection was to comparing the average age of immediate
sires in one case with that of all sires in four generations in the
other case. I showed that when we take only immediate sires
in both cases, it is shown that the average age of the sires of 2.10
horses is practically the same as that of average horses as given
by Mr. Redfield.
He now shows that in the case of the 2.10 trotters, while their
sires were of an average age of 10.4 years, their grandsires
averaged 12.5 years, the great-grandsires 13.5 years, the great-
great-grandsires 14.5 years; the stallions appearing in the next
two lines at the ages of 15 and 15.98 years.
-~ The evident conclusion from this statement is that our best
horses have come from an increasing popularity of younger sires.
But this statement regarding the age of sires in various lines
No. 523] SHORTER ARTICLES AND CORRESPONDENCE433
is used in contrast with conditions in average horses and the
actual figures for the ages of progenitors of average horses are
not given to us, but assumed to be much lower. This assumption
is erroneous.
It would be very interesting to have the average ages of
grandsires, great-grandsires, ete., of the first thousand horses
named in the ‘‘Index Digest’’ and used by Mr. Redfield to
represent average horses.
I have considered it fairer, however, to use a group, though
smaller, more nearly contemporaneous with the 242 horses of
2.10 records used in my previous study. It would be desirable
to have a figure based upon the study of the 2.10 list as it stood
at the end of 1909, but a comparison of the two groups here used
is, I think, a fair one. The group used to represent average
horses and as having been bred at about the same time as the
242' horses with 2.10 records consists of the first 242 horses
registered in Volume 15 of the ‘‘Register.’’
The following tabulation will show that the two groups were
contemporaneous:
| Foaled | Foaled | Foaled | Foaled | Foaled
| before re 1880, |1880-1885. | (1886-1890. 1891-1895. 1896-1900.
0 horses 2 12 40 95 81
Average horses from Vol. 15 2 3 14 116 107
The average age of stallions appearing in each line of the
pedigree of the above is as follows:
AVERAGE AGE OF
G
a. gant Geroko. y van na
2.10 horses 9.4? 1.5 12.53 13.5?
Average horses from Vol, 15 8.28 10.65 11.64 12.78
I am still of the opinion that an impartial study of the figures
does not show that age is, of itself, any factor in the inheritance
of speed.
F. R. MARSHALL,
OHIO STATE UNIVERSITY.
1 Vol. 22 of the ‘‘Year Book’’ gives 279 fast (2.10) horses, but it is
poniai to determine the age of the sires of only 242 of these.
e year less than given by Mr. Redfield to show the age of stallione
at the time the foals were sired.
NOTES AND LITERATURE
RUSSO ON SEX-DETERMINATION AND ARTIFICIAL
MODIFICATION OF THE MENDELIAN RATIOS
In the April number of the NATURALIST Professor Jordan
presents an interesting review of recent literature on sex-deter-
mination in the course of which he gives an extended account
of Russo’s' experiments with lecithin-fed rabbits. Great impor-
tance is attached to this work because it points to conclusions
diametrically opposed to those reached within the last ten years
y nearly every one else who has studied sex-determination either
from the standpoint of the cytologist or from that of the experi-
mental breeder. The nearly unanimous verdict has been that
sex-determination is a matter of gametic differentiation, and that
the sex of a developing organism is not influenced by conditions
of nutrition either applied to it directly or brought to bear upon
the mother. The only exception, apparent but not real, as I
pointed out in 1903, is afforded by organisms in which both
parthenogenesis and sexual reproduction oceur. Abundant nutri-
tion favors parthenogenesis, scanty nutrition causes a return to
sexual reproduction, including the production of males. Russo
has revived the older idea that in non-parthenogenetie organisms
also scanty nutrition is a cause of male-production. If true,
this is a matter of the greatest importance, both theoretical and
practical. Jordan is quite right in so regarding it, but has
apparently failed to appreciate the uncritical character of
Russo’s evidence. This has, however, already been pointed out
by several writers, most recently by Punnett,®? whose brief but
convincing paper seems not to have been seen by Jordan.
Russo himself has never published the results of his experi-
ments as a whole, but only of selected experiments the results of
which were favorable to his thesis. This fact alone would throw
Russo’s claim out of an impartial court, but to be more than
fair to Russo, it may be said that his experiments have been
* Russo, A., ‘f Studien über die Bestimmung des weiblichen TEA r
G. Fischer, pe 1809.
2 Castle, W. E., Bull. Mus. Comp. Zool.
* Punnett, R. C., Proc. Cambridge Phil. Soc., Vol. 15, Pt. 2, p. 92, 1909.
434
No. 523] NOTES AND LITERATURE 435
repeated twice independently, by Basilet and by Punnett, both
times with negative results.
Russo’s original evidence consisted of 100 selected litters of
young borne by lecithin-treated does which included 217 male
and 431 female rabbits, and of 100 control litters (likewise
selected) from non-treated does which included 400 male and
287 female rabbits. The claim is made that lecithin treatment
raised the percentage of female offspring from 41.8 to 56.5.
Russo in this case proves too much, for his selected controls fall
as much below the normal percentage of females as his selected
lecithin-treated cases exceed it and, it is fair to assume, for the
same reason, because they are selected. It is astonishing that a
scientist should present such evidence. A prosecuting attorney
who should be allowed to decide what evidence should be pre-
sented to the court, both for and against, and that all else should
be excluded might convict any one of us of all the crimes enu-
merated in the criminal code.
On the other hand, Basile and Punnett give all their results,
not selected ones; they mean to tell the whole truth, not selected
truth. Basile obtained from lecithin-treated does 66 male and
51 female young, or 43.6 per cent. females, while from controls
he obtained 225 male and 215 female young, or 48.8 per cent.
females. This result is contrary in nature to that of Russo.
If any effect is to be ascribed to the lecithin, it is in this case
male-production rather than female-production as claimed by
Russo. Punnett in repeating Russo’s experiments followed
methods outlined for him in detail by Russo. They are there-
fore particularly satisfactory. From lecithin-fed does he ob-
tained 24 male and 23 female young, or 48.9 per cent. females;
from controls 54 male and 49 female young, or 47.6 per cent.
females. These proportions agree closely with those obtained
by Basile, and accord with Hurst’s extensive observations cited
by Bateson® to the effect that ‘‘under normal conditions male
and female birth are sensibly equal,’’ in the case of rabbits.
Finally Heape® has criticized on cytological grounds the sup-
posed histological distinction between male and female ova of
the rabbit as described by Russo. Heape shows that in all
probability the fat-containing, supposedly female ova are degen-
erating ova. '
* Basile, C., Atti Acad. Lincei, Vol. 17, p. 643, 1908.
ë Bateson, W., ‘‘ Mendel’s Principles of Heredity,’’ 1909.
*Heape, W., Proc. Cambridge Phil. Soc., Vol. 14, p. 609.
436 THE AMERICAN NATURALIST [Vou.XLIV
If further evidence were wanting of the wholly uncritical
character of Russo’s work, it might be found in his analysis of
the results of crosses involving Mendelian color characters.
Jordan correctly states Russo’s claim, though not his evidence.
The claim is that when albino or spotted females were mated
with gray or black males, the color character of the latter dom-
inated in the young, but when the same females were first treated
with lecithin and then mated with a black male the color char-
acter of the mother occurred in part or all of the young. The
conclusion is drawn that lecithin treatment of the mother is a
practical means of fixing a desired maternal character as a racial
character, a claim so astonishing and so important, if true, that
with Jordan’s indorsement it is in danger of being taken seri-
ously by readers of the Narurauist. For that reason I have
been prompted to examine Russo’s evidence carefully and to
write this note. His evidence consists of four cases, all the cases
bearing on this point concerning which he gives detailed infor-
mation, and he states that these are his best cases.
Case 1.—A young albino (Polish) female was treated with
lecithin and mated with a gray male and produced two gray
young. The lecithin treatment was continued and she was now
mated with a black male and had eight young, six white and two
black. The reader is led to conclude that the further lecithin
treatment is responsible for the appearance of white young in
the second litter. But is it? No evidence is given as to the
gametie character of the male parent of either litter. If the
gray male was homozygous he should have produced, as observed,
only gray young, though the production of two young only was
no adequate test of his character. The same male should have
been used after the ‘‘further’’ lecithin treatment if information
were desired about the effect of lecithin, but this was not done.
A new untried male of a different color, black, was used. He
produced both albino and black young, a result which indicates
that he was heterozygous. If so, the result obtained is such as
would have followed without any lecithin treatment whatever!
The case proves absolutely nothing, because neither colored
parent was tested, so far as we have any information. Russo
seems to think that the first litter affords a criterion of what the
second should give by a different male parent, a conclusion which
no one familiar with Mendelian principles would entertain for
a moment.
No. 523] NOTES AND LITERATURE 437
Case 2.—A young Himalayan (albino) female rabbit was
treated with lecithin and mated with a black male. She pro-
duced by him three litters of young. The first litter contained
six young, all black. The second litter contained four young,
two of which were Himalayan, two yellow-and-white.? The third
litter contained seven young, concerning the color of one of
which no account is given; four were Himalayan, one yellow-
and-white and one black-and-white. The case (a selected one)
is supposed to show that continued treatment with lecithin pro-
duces more young of the maternal type in later than in earlier
litters. But a selected case can not fairly be used to show any-
thing of the sort. Only a fairly uniform result of repeated
experiments could establish it. Under the circumstances we
can only ask what the expected Mendelian result would be in a
ease like this if no lecithin treatment were involved, and then
inquire whether the observed result differs in any respect from it.
If no lecithin treatment were involved we should say that the
black male used was heterozygous in the recessive characters
albinism, spotting and yellow; and the expectation would be that
he would produce young of five sorts in one of the following
distributions, depending on the gametic character of his albino
mate:
Black Yellow Black and white Yellow and white Albino
$ i 1 1 4
3 : 3 $ 1 ‘ 1 $ 8
9 : 3 t 3 : 1 i 16
The observed distribution for the three litters is 6:0:1:3:6.
This is so good a Mendelian result that it would not call for any
special comment in ordinary breeding work. Further matings
would be called for, but it would be surprising if these did not
supply the missing class, yellow, and give numbers agreeing more
closely with one or another of the suggested ratios.
No control matings of either parent in case 2 are recorded
by Russo.
1 Regarding this class Russo says they were of the same race, as the
mother but with yellowish or white ground-color (‘‘von derselben Rasse,
aber mit gelblicher bzw. weisser (wie in Fig. 27), Grundfarbe’’). But the
photograph, Fig. 27, shows unmistakably that these animals were not albinos
at all but Dutch-marked colored animals, which invariably have dark eyes.
A spotted dark-eyed animal is not by any means of the ‘‘same race’’ as
an albino, as is well known to students of genetics. Spotting behaves as a
Mendelian unit-character wholly independent of albinism.
438 THE AMERICAN NATURALIST [Vou. XLIV
Case 3.—The statements of Russo concerning this case are very
incomplete. A spotted ‘‘Olandese’’ female after lecithin treat-
ment was mated with a silver-gray male and produced three
spotted and one self-colored young, which are figured. Before
treatment with lecithin she had been mated under normal con-
ditions (once with the same silver-gray male, ‘‘mit demselben
grau Männchen einmal,’’ but we are not told that he was the
father of the young, we are rather left to infer that she may
have mated with other males also. Five young were afterward
orn—‘‘es erzeugte dann später 5 Junge,’’ all gray. Again the
female was mated under similar uncertain conditions, ‘‘unter
den gleichen Bedingungen,’’ and produced four gray young.
Since in a third litter, after lecithin treatment, she produced
spotted young, it is concluded by Russo that the lecithin treat-
ment was responsible for the changed result. But before ac-
cepting this conclusion we should like to be assured that one and
the same male was used in both cases. The silver male may have
been heterozygous in spotting, the father of the earlier litters not.
Case 4.—Two Himalayan (albino) females, sisters, were mated
with the same black male. One of the two was lecithin treated,
the other was not. Both produced black young, five each. This
looks like a bad case to select in support of lecithin influence, but
we are told further that in the following year, when lecithin
injections were employed forty days previous to copulation, a
litter of two Himalayan young was obtained. The sire of the
litter is figured but we are not told whether he was the same
as the one used the previous season. This omission is signifi-
cant. The male figured was evidently heterozygous in albi-
nism, but it is a pretty safe guess that he was not identical
with the male used the previous season, which was in all
probability homozygous in black. In this case as in the others
described by Russo it is impossible to avoid the impression
that the author is not making a full and frank statement of
facts but is stating half-truths likely to mislead the unwary.
In Jordan’s ease this is exactly what has happened. He says:
‘‘The evidence here appears unequivocal that external conditions
(e. g., nutrition) can determine the kind of sex and entirely
vitiate the Mendelian scheme of ordinary crosses’’ [italics mine}.
I have, however, presented in detail all the evidence which Russo
= gives in support of the assumed vitiation of Mendelian inherit-
ance. I think the reader will agree with me that the evidence
No. 523] NOTES AND LITERATURE 439
is more than equivocal and that the vitiation is of reasoning not
of inheritance. -
So far as I know, only one other investigator besides Russo
has laid claim to having modified the ordinary course of Men-
delian inheritance by external conditions. Such a claim, if I
rightly understood him, was made by Professor W. L. Tower, in
a paper read at the last annual meeting of the American Society
of Naturalists, in the case of beetles of the genus Leptinotarsa.
Detailed information regarding the cases in question will be
awaited with much interest. It is to-be hoped that this will
prove more complete and satisfactory than Russo’s.
W. E. CASTLE.
HARVARD UNIVERSITY,
June 11, 1910.
THE BUBONIC PLAGUE
Busonic plague is primarily an animal disease. Its original
victim is said to have been a species of rodents found in the
mountains of Mongolia. Several Russian scientists have sought
to establish this hypothesis, according to which the Arctomys
bobac, a Mongolian marmot, is the primitive animal host. In it
the disease is permanently prevalent, and from it both man and
the rat are infected periodically. According to the view of
these writers the final eradication of the plague from our globe
would be accomplished by the extermination of this rodent.
That this view is over-optimistic may be inferred from the prob-
able existence of other ancient centers from which plague epi-
demics have originated, and in which, consequently, permanently
infected animals are at home, and also from the recent origin of
such an established center of animal infection on our own con-
tinent.
In the introduction to an article on Plague Eradication Meas-
ures (Squirrel Campaign) in California, Rucker? comments on
the epizootic which for four years has been spreading among the
ground squirrels of Contra Costa County, and which more re-
cently has been reported from other districts also. The animal
infected is Citellus beecheyi, which is reported by ranchers to
have died by the thousands in 1904-5-6. In appearance and
habits, it resembles closely the Thibetan marmot referred to
above. Not until there came cases of human plague due to
plague-infected squirrels was the disease of the latter subject
* Journal Amer. Med. Assn., Vol. 53, p. 1995.
440 THE AMERICAN NATURALIST [Vou. XLIV
to careful scrutiny. Wherry? first showed in a conclusive man-
ner that ground squirrels, obtained from two widely separated
sections of California, were infected with the bacillus of bubonic
plague. There remained to be ascertained the extent of the
infection and appropriate methods for the extermination of the
infected animals and the eradication of the disease, which had
gained apparently a permanent foothold on the state of Cali-
fornia. The records of these investigations form one of the
most interesting and important chapters of medical zoology yet
written.
The splendid work which has been done by the Public Health
and Marine Hospital Service on the Pacifie coast in connection
with the problem of stamping out bubonic plague, has included
investigations on the rats and also on native rodents, which have
established important points in the relations of these animals
to the spread of that disease. While no cases of human plague
have been reported for many months, yet plague-infected rodents
have been killed at one point or another as recently as February.
The disease is not common, since about 2,000 squirrels from one
county were examined before an infected individual was found.
Nevertheless, one can not doubt its continuance among the wild
rodents, or question the advisability of prosecuting the campaign
for the total eradication of the infeeted animals. The service
has published? complete statistics of work to date and a map
showing the area studied and the prevalence of plague among
ground squirrels.
The rodents in which plague infection has been demonstrated
include both the introduced species, Mus rattus, the black rat,
and Mus norvegicus, the brown rat, and also the native species,
Citellus beecheyi, the California ground squirrel, and Neotoma
fuscipes, the brush rat. The work of McCoy* corroborated fully
the findings of Wherry, and left no doubt that the disease among
ground squirrels is due to the same organism that causes bubonic
plague among rats and men. The experimental evidence which
the latter reports in a conservative and critical manner includes
several typical cases of plague in human beings where the diag-
nosis has been verified by bacteriological methods, and where
the cases ‘‘have been traced to squirrel infection as clearly as
one can trace such things.” While McCoy states that in his
2 Journal of Infectious Diseases, Vol. 5, p. 485.
=- ***Public Health Reports,’’ Vol. 25, p. 585.
_ ‘Public Health Reports,’’ Vol. 25, pp. 27-33.
No. 523] NOTES AND LITERATURE 441
opinion the number of human beings infected directly by squir-
rels will never constitute a large element in the infected region,
yet, on the other hand, one can not deny the patent facts that
the infection of native rodents provides a retreat in which the
disease is relatively safe from elimination and also a source from
which it may be at any time transmitted anew to the human
species. The transmission from rat to man through the inter-
mediation of the fleas is easily conceived. The intimate associa-
tion of the rat with human dwellings and with places constantly
visited by man makes the transfer of the infeeted fleas an easy
matter. The transmission of the disease in similar fashion
among the animals in a squirrel colony is equally readily under-
stood, though the booby owl, which regularly occupies the same
burrows with the ground squirrel, may play the important part
in the dissemination of the disease, since the bird, flying from
burrow to burrow, might readily carry infected fleas over long
distances. If this be true, the eradication of the disease is greatly
complicated.” The intimate association of rats and ground
squirrels has been observed repeatedly. In one locality in the
outskirts of a city both were taken alive from the same burrows
and rat fleas were combed from the hair of the squirrel.*®
The mode of transfer from squirrel to man is more difficult
to understand. Simpson’ suggests that cattle on the range are
the unrecognized factor which provides for the conveyance of
infected fleas from squirrel to man. He states that fleas abound
in and about squirrel villages and the cattle as they range over
this territory lie down to rest in and among these villages.
Since the fleas quickly desert an animal after death, the cattle
will more readily acquire fleas in villages containing infected
squirrels, and especially if dairy cattle were concerned, the daily
contact with men would give abundant opportunity for the
transfer of the infected fleas. Some of the squirrel villages
known to be plague infected are so isolated as to afford only
occasional -contact with man, yet cattle were seen grazing near
these villages and may furnish the connecting link in trans-
mission.
Of the species of wild rodents known to be infected in nature,
the California ground squirrel, Citellus beechyi, is unquestion-
ably the most important. It has also been the longest recognized —
ë Rucker, W. C., ‘Public Health Reports,’’ Vol. 24, p. 1225.
*¢< Public Health Reports,’’ Vol. 25, p. 6
1t‘ Public Health Reports,’’ Vol. 25, p. 250.
442 THE AMERICAN NATURALIST [Vor. XLIV
as an element in the plague situation. Its habits and distribu-
tion have been outlined by Merriam, who also discusses means
for its systematice destruction.
Much less well known is another California rodent which has
very recently been shown to be susceptible to bubonic plague
under natural conditions. This species is the woodrat, Neotoma
fuscipes annectens Eliot. It is distinctly a new world form, of
which several species occur on the Pacifice coast and into the
desert region as far as Utah and Colorado. Evidently, if the
infection can be transmitted from one to another of these species,
the disease will thus extend over a large area. ‘Rucker,’ says
of their habits:
Wood rats are nocturnal in their habits and are seldom seen in the
light of open day except when it is very cloudy. For the most part,
they are found along small wooded arroyos, in which they build their
nests, often of the most elaborate design. Those which the writer has
had the opportunity of dissecting consist of pieces of driftwood ar-
ranged in a pile, sometimes 6 or 7 feet in diameter and 3 feet high.
sharp sticks. It is said that where cactus is plentiful the tunnel is
lined with cactus spines as a protective measure against other mammals.
The interior of the nest is frequently arranged into three stories, and
contains storehouses and living rooms. Usually there is an exit which
is frequently found near the base of a tree. This is utilized as a means
of eseape when the ordinary entrance is blocked and some enemy begins
to tear the nest apart. The storehouses in several instances contained
large quantities of the corms of a plant growing in the immediate
neighborhood. Although wheat was growing but a few hundred yards
away, none of this was found in these nests. In certain regions the
Neotoma store up large quantities of mesquite beans, and these caches
are raided annually by the Indians, who use them for food. They also
store up mushrooms, certain varieties of puffballs and acorns.
In view of the part played by fleas in the transmission of the
disease, it is interesting to note the average number of fleas from
a squirrel is much larger than from a rat or from any. other host
yet observed. Much collateral work has been done on the species
of fleas, found on the various rodents which suffer from bubonic
plague, and on the relations of these fleas to the transfer of the
disease as shown by their ability or readiness to bite man and
other hosts. The majority of the two rat fleas common in San
Francisco, viz., Lemopsylla cheopis Roth and Ceratophyllus
8 tt Publie Health Reports,’’ Vol. 23, No. 52.
9 Publie Health Health Reports, * Vol. 25, No. 1, p. 2.
No. 523] NOTES AND LITERATURE 443
fasciatus Bosc., will bite man under experimental conditions,
while the squirrel fleas, Hoplopsyllus anomalus and Cerato-
phyllus acutus, feed readily on man’s blood.!? The same authors
have also shown" that fleas from rodents will adapt themselves
to a host of a different species and that fleas from squirrels will
attack rats even in the presence of their normal host. Plague
bacilli have been demonstrated in both the common squirrel
flea, Ceratophyllus acutus, and also in the lice (probably Hæma-
topinus montanus) very commonly found on the same host.??
Experimental work has also been done to determine the suscepti-
bility to bubonic plague of other rodents in which the disease
has not yet been reported under natural conditions.** Finally in
experimental cases'* rat fleas have conveyed plague from rats to
ground squirrels and squirrel fleas from squirrel to squirrel,
and also to guinea pigs and rats. H. B. Warp.
DESERT PLANTS!
In the opinion of the reviewer, this book constitutes the most
noteworthy contribution thus far submitted from the Desert
Botanical Laboratory. In a measure it may be said to be the
outcome of previous contributions and others not hitherto pub-
lished. Investigations in progress there during the several years
since the establishment of the desert laboratory, while they have
a wider range of application, have centered in the effort to de-
scribe and interpret the interplay of stimulus and response as
between desert environment and plants in the desert. It in no
way detracts from the merit of Professor Spalding’s contribution
to say that the results of these investigations constitute a promi-
nent feature of the book, and indeed it stimulates increased ap-
preciation of his work to observe that he assumed the difficult
task of so correlating the results of a staff of specialist investi-
gators as to bring about a reasonable measure of interpretation
of the rôle of environmental stimuli in shaping the origin, dis-
tribution, associations and movements of desert plants. The
book lays claim to being only a partial interpretation of the
® McCoy and Mitzmain, ‘‘Public Health aioe * Vol. 24, No. 8.
“íí Publie Health Reports,’’ Vol. 24, p. 101
* Geo. W. McCoy, ‘‘ Publie Health es ee 24, p. 475.
® Geo. W. McCoy, Jour Infectious Diseases p. 283.
* Public Health Reports, Vol. 25, p. 465 and 1
***Distribution and Movements of Desert panne ” by Volney M.
Spalding, Carnegie Institution of Washington, publieation No. 113, October,
1909, pp. 144, with 30 plates.
444 THE AMERICAN NATURALIST [Vou. XLIV
problems of desert vegetation and expressly points out the need
of continued investigation not merely of the area under con-
sideration (the so-called ‘‘Desert Laboratory domain’’), but of
comparative studies of more areas widely distributed through
the desert.
Having set itself the task of interpreting the ways of plants
in the desert, the management of the desert laboratory began
by investigating intensively a small area of typical desert country.
The laboratory site appears to have been selected with a view
to having at its door this ideal field of investigation, which is an
area of not over a mile in radius.
Professor Spalding rightly supposes that no other small area
anywhere has had centered upon it the intensive study of so
many well-equipped investigators as has this typical bit of desert,
and he might have added that perhaps in no other case has there
been a more adequate equipment of apparatus and instruments
for work of a precise nature and, in the reviewer’s opinion,
no other instance where more adequate methods have been de-
vised for pursuing the investigations.
The work of collaborating specialists is largely presented as
distinct sections or chapters of the boo
The geology of the vicinity of the Tumamoe Hills is presented
with particular reference to its relation to the distribution and
movements of plants by Professor C. F. Tolman, of the Univer-
sity of Arizona (pp. 67-82), in the chapter on Environmental
and Historical Factors. In this chapter also Dr. B. E. Living-
ston contributes a section (pp. 83-93) on the soils of the desert
laboratory domain. Reference is made here likewise to the evap-
oration studies conducted by Dr. Livingston. It is of course
beyond the range of the present reviewer’s task to take up Dr.
Livingston’s work in detail, but it seems an appropriate place
in which to point out a striking case in which endowed research
has yielded results of far-reaching application in behalf of eco-
nomic development, namely, in the relation of soils and evapora-
tion to plant production generally.
| r. W. A. Cannon, of the Desert Laboratory staff, contributes
a ae nee study of the root system of the giant cactus
Pres giganteus), together with a comparison of the root sys-
ms of certain other marked desert species (pp. 59-66). Such
saa studies furnish the source of reliable data for conclu-
sions as to the relation PAET the habits and structure of plants
bear to their distributi
No. 523] NOTES AND LITERATURE 445
Floristic investigations have been undertaken by Professor
J. J. Thornbur, botanist of the Arizona Experiment Station, and
reported in an effective manner under the title Vegetation Groups
of the Desert Laboratory Domain (Chap. IV, pp. 103-112). In
this contribution, floristice studies, instead of being dry lists of
species, are made to contribute materially to the chief ques-
tions as to the origin, association and movements of the vegeta-
tion.
In the chapter devoted to defining plant associations and habi-
tats, pages 24 to 27 embrace an account of the lichens of the
Laboratory domain, by Professor Bruce Fink, of Miami Univer-
sity.
Distributional maps with accompanying notes were prepared
by Mr. J. C. Blumer, of the laboratory staff. In the reviewer’s
opinion maps of this sort, showing, as they do, location and indi-
vidual frequence of notable species, are of essential help to the
reader, as they must have been indispensable to the writer of the
book.
Finally, among the collaborative contributions is a chapter
(V, pp. 113-119) on the Origin of Desert Floras, by Dr. D. T.
MacDougal, director of the Desert Laboratory and of the Di-
vision of Botanical Research of the Carnegie Institution of
Washington.
In this study of the vegetation of the Desert Laboratory domain
Professor Spalding has led the attack from the plant side, seek-
ing to define the actual conditions of distribution, association
and movements in the vegetation as a whole and specifically in
the case of prominent desert species, and always with a view to
relating facts of distribution, structure, ete., with the environ-
mental conditions under which they have been worked out.
Accordingly, a considerable portion of the book is of a deserip-
tive nature. Chapter I presents the plant associations and habi-
tats of the laboratory domain. The author distinguishes some
twelve associations exclusive of parasitic and symbiotic plants
and miscellaneous introduced species, meaning by ‘‘association’’
an aspect or phase of vegetation, such, for example, as the
cottonwoods and willows of a river bank, a mesquite forest, or
chaparral made up chiefly of palo verde and catclaw or, on the
other hand, of Mexican greasewood. These associations reflect
topographic and soil conditions of the area. Remembering the
traditional view as to the hostility of the desert toward plants,
one is rather surprised to learn that this inhospitable domain
446 THE AMERICAN NATURALIST [ Vou. XLIV
harbors between four and five hundred species which are by no
means all xerophytes, but species adjusted to the most diverse
moisture requirements. To be sure, this is due in a measure to
the inclusion of a river and its flood plain in the Laboratory
domain. Still, a surprising number of species manage to exist
on the arid situations without being marked by any special
xerophytie structures.
Chapter II takes up in detail an analysis of the distribution of
certain of the most prominent desert species. As to the factors
determining the local distribution and association of species,
these are, just as everywhere else, chiefly topographic and soil
conditions. Manifestly it is primarily the water supply as af-
fected by conditions of soil and topography which is the critical
factor, but soil drainage or aeration is found to play a large
rôle and, indeed, is the determining factor in the distribution
of certain species.
Special attention may be called to that portion of Chapter II
which presents the facts and conclusions as to aspect preference
as exhibited on the laboratory domain. The question, in brief, is
to account for the differences in the vegetation covering of slopes
having a general southerly exposure as compared with those hav-
ing a general northerly one. Here is found fully justified the
claim advanced by certain American plant ecologists, that only
by exact quantitative study of the items involved may one expect
to arrive at an explanation of distribution, association and move-
ments of plants. In this connection the study of the root sys-
tem of Cereus giganteus sustains its status as a model piece of
ecological investigation.
Another thing which we learn from this chapter (II) is that
while, as we supposed, the chief struggle of plants in the desert
is against the physical environment, there is still a right marked
element of competition amongst desert species with its conse-
quent features of accommodation (commensalism?) or of exter-
mination and succession. Since, however, the problems of distri-
bution, association and movements are so little complicated by
the factor of crowding as compared with mesophytic forest so-
_ eieties, for example, it has seemed to the reviewer that the desert
furnishes about the simplest as well as the most inviting point
of attack for the ecologist.
In chapter VI under Review and Discussion and in Chapter
VII, a summary, Professor Spalding brings forward in con-
densed_ a a $ survey of the work of investigation done on the
No. 523] NOTES AND LITERATURE 447
laboratory domain and particularly the tentative or positive con-
clusions he is able to formulate as a result of these investigations.
So far as regards the local distribution and association of species,
the reviewer is unable to discern that the general view thus far
held as to the rôle of the so-called edaphic factors is in any wise
modified, but our knowledge of the manner in which this rôle
is played has been materially enriched by the work of Professor
Spalding and his collaborators.
Foregoing the temptation to comment on many other interesting
details of this book, there remains yet to consider the crown-
ing question as to whence came the desert vegetation and how
did it come to be what it is? Upon this point Professor Spal-
ding’s conclusions are quite positive, as indicated in the following
words from his book:
The general continuity of geological history since the Tertiary indi-
cates a relatively long period within which plants of the Laboratory
domain have one by one or at any rate by no mass movements, become
established in their places. There is reason to believe that throughout
this period the processes now going on before our eyes have been in
progress. The present flora, therefore, may be assumed to be merely
the final stage so far of just such a series of events as are now
observable. . . . The small area within its limits (the Laboratory do-
main) has received representatives of genera that have shared in the
great migrations south and north along the Cordilleras, but through
the time that has elapsed since the ater movements it has also
received by TAY ordinary means the plants that have come and are
still coming to
We are Be to gather from these words whether Professor
Spalding means that ‘‘the processes going on before our eyes’’
relates simply to movements of vegetation or includes also modifi-
cations whereby ecological types—as, for example, the giant cac-
tus—arise. In this connection, Dr. MacDougal’s chapter on the
origin of desert floras is illuminating. His view is in agreement
with Professor Spalding’s as to the fact that there is little evi-
dence of extensive migrations of the characteristic xerophytes of
this desert from which it is to be inferred that these investigators
believe the Sonoran desert to have been and to be now a center
of origins for its flora. MacDougal brings us face to face with
the question as to how the desert makes its flora if one may
give the question this popular east. He rejects the idea of so-
called adaptive changes representing ontogenetic and morpho-
genetic responses (made by a plant when exposed to desert con-
448 THE AMERICAN NATURALIST [ Von. XLIV
ditions, for example) as being not necessarily adaptive and in
any event not capable of being transmitted to offspring. He
believes, however, that what has been observed to take place
under experimental conditions might take place when plants or
generations of plants are subjected to the stimulus of desert en-
vironment. His words are:
The influence of external conditions upon the germ plasm, however,
has been seen to produce irreversible changes in a hereditary line by
which new combinations of qualities and new characters were called
out, which were fully transmissible. Furthermore the newly produced
forms perished in some localities endured by the parental type, but
exceeded it in weathering the conditions of other localities.
In the treatment of the larger aspects of the question of the
origin and movements of desert plants the intensive study of a
single small area fails to furnish a large enough fund of com-
parative data to make a wholly satisfactory basis for conclu-
sions. The reviewer would modestly suggest that the Sonoran
desert (meaning the desert areas of our southwest and of north-
ern Mexico) is a very large and diverse region in which not
merely individual species but whole genetic groups have become
xerophilized (with apologies for spurious coinage), and that cor-
related investigations at numerous points and a study of genetic
relationships in connection with distribution, association, move-
ments and modification (meaning transmissible qualities or char-
acters) would furnish a broader basis for the interpretation of
the ways of plants in the desert at large.
In a final word the reviewer would invite attention to the
status of Professor Spalding’s book considered. in relation to
plant ecology. In full appreciation of other recent ecological
contributions of similar merit the opinion is advanced that
this book stands in a special way as an index of the new era
in geographic ecology in which a field of botanical research
which was prone to abound in verbosity and in the discovery of
‘‘adaptations’’ has been brought to the status of a more exact
science employing quantitative methods of study. It is not
_ boastful to say that this newer phase of plant ecology repre-
_ sents especially the outcome of the teaching and investigations
of a small group of American botanists (of which group the
_ present reviewer can not claim to be a member) who have sought
to put the study of plant relations upon the same basis as that
permea in the study of plant physiology in the limited sense.
Wiuiam L. BRAY.
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New York
es
VOL. XLIV, NO. 524" AUGUST, 1910
THE
AMERICAN
NATURALIST
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
Page
I. Chromosomes and Heredity. Professor T. H. MORGAN - - - - = 449
Il. Spiegler’s “White Melanin” as related to Dominant or Recessive White.
DR. ROSS AIKEN GORTNER =- - - - 497
EI. Shorter Articles and Correspondence: A Pickwickian ae to Our
Knowledge of Wasps: Professor KARL PEARSON -~ - -5 =- + 503
IV. Notes and Literature: Heredity, DR. W. J. SPILLMAN - - + - + 504
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THE
AMERICAN NATURALIST
VoL. ADIV August, 1910 No. 524
CHROMOSOMES AND HEREDITY
PROFESSOR T. H. MORGAN
COLUMBIA UNIVERSITY
THE INDIVIDUALITY OF THE CHROMOSOMES
We have come to look upon the problem of heredity
as identical with the problem of development. The word
heredity stands for those properties of the germ-cells
that find their expression in the developing and de-
veloped organism. When we speak of the transmission
of characters from parent to offspring, we are speaking
metaphorically; for we now realize that it is not charac-
ters that are transmitted to the child from the body of
the parent, but that the parent carries over the material
common to both parent and offspring. This point of
view is so generally accepted to-day that I hesitate to re-
state it. It will serve at least to show that in what I am
about to say regarding heredity and the germ-cells I shall
ignore entirely the possibility that characters first ac-
quired by the body are transmitted to the germ. Were
there sufficient evidence to establish this view, our prob-
lem would be affected in so far as that we should not
only have to account for the way in which the fertilized
egg produces the characters of the adult, but also for the
way in which the characters of the adult modify the
germ-cells.
The modern literature of development and heredity is
permeated through and through by two contending or
contrasting views as to how the germ produces the char-
449
450 THE AMERICAN NATURALIST — (VoL. XLIV
acters of the individual. One school looks upon the egg
and sperm as containing samples or particles of all the
characters of the species, race, line, or even of the indi-
vidual. This view I shall speak of as the particulate
theory of development.
The other school interprets the egg or sperm as a kind
of material capable of progressing in definite ways as it
passes through a series of stages that we call its develop-
ment. I shall call this view the theory of physico-chem-
ical reaction, or briefly the reaction theory. The resem-
blance of this comparison to the traditional theories of
preformation and epigenesis is obvious, and I should
willingly make the substitution of terms were it not that
the terms preformation and epigenesis have certain his-
torical implications, and, as I wish to emphasize certain
things not necessarily implied in the historical usage, I
prefer descriptive terms other than these overladen with
so many traditions.
A few preliminary considerations will serve to clear
the way for the detailed examination to follow:
The particulate theory may appear more tangible,
definite and concrete because it seems to make a more
direct appeal to a material basis of development and
heredity. The theory of physico-chemical reaction may
seem more vague and elusive, since the responses and
reactions to which it must appeal are as yet little known.
But this distinction is not one of much importance. For
the particulate theory requires as elaborate a series of
processes or changes to account for the distribution of
the postulated particles and their development into char-
acters as does the reaction theory itself, and on the
other hand the reaction theory may rest its claims on
as definite a physical or material basis as does the
other view. One theory lays emphasis on the material
particles of development, the other on the changes or ac-
tivities in the same material. Both views assume that
there is something in the egg that is responsible for
every detail of character that later develops out of the
egg. Since we do not know what this something is, it
No. 524] CHROMOSOMES AND HEREDITY 451
must be admitted at the outset that the distinction be-
tween the two is largely theoretical and possibly temper-
amental. To some minds it appears that to admit that
every detail of character is represented by the egg must
mean that something material in the sense of some actual
particle that stands for each detail must be present. To
other minds it seems only necessary to admit that eggs
are made of different materials in order that the outcome
of the development may be different, and that these dif- |
ferences between eggs, while leading to differences in the
end product, need not be conceived as different material
particles in the sense that the particles become the ulti-
mate characters that differ.
Both views postulate an initial difference in the egg,
but one view conceives the differences in the egg to be
associated with particles that are in some way directly
responsible for the different characters, while the other
view conceives adult characters to be the product of an
elaborate series of processes and that the material dif-
ferences in different eggs are too remotely connected
with the end product of their development for us to
think of those differences in terms of special or separate
particles except in the purest symbolic fashion. Which-
ever view we adopt will depend first upon which concep-
tion seems more likely to open up further lines of profit-
able investigation, and second which conception seems
better in accord with the body of evidence at hand con-
cerning the process of development.
It may be said in general that the particulate theory is
the more picturesque or artistic conception of the de-
velopmental process. As a theory it has in the past
dealt largely in symbolism and is inclined to make hard
and fast distinctions. It seems to better satisfy a class
or type of mind that asks for a finalistic solution, even
though the solution be purely formal. But the very in-
tellectual security that follows in the train of such the-
ories seems to me less stimulating for further research
than does the restlessness of spirit that is associated
with the alternative conception. The purely adventur-
452 THE AMERICAN NATURALIST [ Vou. XLIV
ous character of any explanation offered by the reaction
theory seems more in accord with the modern spirit of
scientific theory. But when we lay aside these generali-
ties concerning the two theories and descend to particu-
lars we may find at times very real distinctions between
the two views. For example :—
The original conception of preformation postulated an
actual material embryo in the egg; epigenesis denied
the existence of that embryo, and justified its denial.
Here surely there was a real distinction.
But the problem has refined itself in modern times.
We no longer look for an actual embryo preformed but
we look for samples of each part, which samples by in-
creasing in size and joining suitably to other parts make
the embryo. This is modern preformation. Is it not a
question of fact whether such samples exist in the egg?
The contrasting theory looks upon the germ-cells as
consisting of one fundamental material, or at most of a
few materials that change as development proceeds, until
finally the end-product of the changes are the kinds of
materials that we know to differ chemically in a number
of ways. It seems to me that there is here also a real
difference between the two views, and that the one can
be as clearly formulated as the other: I propose, there-
fore, to examine further these contrasting views in the
light of our present opinions concerning the egg and its
mode of development.
The modern theory of particulate inheritance goes
back no further than the discovery that the sperm trans-
mits equally with the egg the characters of the race;
and with the discovery that the most conspicuous thing
that the sperm brings into the egg is the nucleus of the
male cell or more specifically its chromatin. Around
these simple statements the whole edifice has been
erected. We owe to Weismann more than to any other
biologist, the peculiar trend that this speculation has
followed. It has seemed to many biologists that the only
interpretation of the facts just stated could be that
special turn that Weismann has given to them.
No. 524] CHROMOSOMES AND HEREDITY 453
By a curious twist of logic Roux brought the chromo-
somes into the discussion. He argued that the karyo-
kinetic figure is an instrument of such a sort that we
must suppose its function to be that of nicely separating
at each division the different kinds of materials of which
the chromosomes are composed, or supposed to be com-
posed. Were it only necessary, he argued, to divide the
chromatin quantitatively into equal parts a far simpler
mechanism ought to suffice. Weismann took this argu-
ment in good faith, and built up his theory upon it.
But if one thing seems more certain than anything
else in modern cytological work it is that in most cases
the karyokinetic figure divides the chromatin of the chro-
mosomes into exactly equal parts, irrespective of what
the fate of the cells is to be. We find that the chromo-
somes in the different tissues are identical as far as our
methods reach. Observation gives a positive denial to
the Roux-Wiesmann assumption. In fact, Roux himself
has later abandoned this position. We find in many
quarters a strong disinclination to the view that the chro-
mosomes are responsible in this sense for. the process of
development.
This feeling has interested me a good deal in recent
years, especially since I myself have felt the same disin-
clination to reduce the problem of development to the
action of specific particles in the chromosomes. In my
own case and possibly in the minds of others this hesita-
tion is due in the first place to a distaste for the particu-
lar form of this theory that Weismann has made so pro-
nounced a feature of his speculations, and in the second
place to a feeling that it is unsafe or unwise to reduce
the problem of heredity and development to a single
element in the cell; when we have every evidence that in
embryonic development the responsive action of the cyto-
plasin is the real seat of the changes going on at this
time, while the chromosomes remain apparently constant
throughout the process.
The feeling against the view that ascribes everything
to the chromosomes has been increased also by the as-
454 THE AMERICAN NATURALIST [Vou. XLIV
sumption that unit characters in heredity are preformed;
especially since those who assume such characters to be
the basis of heredity have as a class—with some excep-
tions, however—shown a strong predilection towards lo-
cating their indivisible units in the chromosomes.
These and other conditions have combined to produce
two opposing views and the chromosomes have come to
be the chief bone of contention. I shall attempt, there-
fore, to limit my discussion to this topic, at the risk of
appearing to take rather a narrow point of view.
We can trace to the important work of Boveri a great
deal in our modern conception of the idea of the chro-
mosomes in heredity and development. We owe to
Boveri the current conception of the individuality of the
chromosomes; we owe to him the discovery of facts that
go to show in a sense the independence of the chromo-
somes of the cytoplasm in which they lie; and most im-
portant of all we owe to him the idea that the chromo-
somes may be individually different and that development
depends on the presence in the cells of samples of each
kind of chromosome. Let us take up these points in turn.
Individuality is a word with vague meanings. Boveri
has, however, defined very precisely the limited way in
which he applies this term to the chromosomes. Whether
we agree that the facts show the chromosomes to possess
this kind of individuality is a question to be further ex-
amined, but admitting differences of view possible
Boveri’s careful analysis of the situations must excite
our admiration and respect. Wilson’s expression, the
genetic continuity of the chromosomes, seems, however,
to better express Boveri’s attitude than the word individ-
uality used by Boveri himself so far as the facts of direct
observation are concerned; but if we extend this term to
include Boveri’s deductions from certain experimental
work, then the word individuality means something more
than genetic continuity.
Applied to the chromosomes, individuality means that
the chromosome that passes into the resting nucleus
is substantially the same that comes out at the next
No. 524] CHROMOSOMES AND HEREDITY 455
division. This interpretation has met with some oppo-
sition. Every cytologist is familiar with the fusion of
the chromatin threads in the resting nucleus. If they
fuse, what guarantee is there that they will separate
again along the exact lines of union? If the separation
is not exact the materials of the chromosomes would,
before long, become completely intermixed. It is this
difficulty that has created a presumption against the
theory of the individuality of the chromosomes.
Despite the supposed objection the fact remains indis-
putable that in cells where the chromosomes can be dis-
tinguished by their distinctive sizes, the same sized
bodies emerge after every supposed fusion in the resting
nuclei. The most convincing evidence for individuality
in this sense is that brought forward by Boveri’s study
of the position and shape of the chromosomes as they
emerge from the nucleus at the two-cell stage of Ascaris.
He shows that there is often a remarkable agreement
between the chromosomes in the two sister cells which
can only be explained on the grounds that the chromo-
somes have retained in the resting stage the same form
and position that they had when they went into the rest-
ing nucleus, and this arrangement can be traced back to
the way in which the chromosomes divided in the segmen-
tation spindle.
This evidence points to the conclusion that the central
part at least of the chromosomes has not been lost by
fusion in the resting stage. It is important to note that
we can not explain their reappearance after each resting
stage by means of the assumption that they differ chem-
ically and segregate according to their kinds of mate-
rials, because in each nucleus there are two chromosomes
of the same sort, one paternal the other maternal in
origin, but identical otherwise. The pairs may lie in any
position with regard to each other in the resting nucleus.
Hence like chromosomes they might often interlace, and
there is no guarantee that later these materials would
move into the two original chromosomes rather than con-
centrate around one of the two centers. It has been sug-
456 THE AMERICAN NATURALIST [Vow. XLIV
gested by Hertwig and held also by others, especially by
Fick, that the formation of the chromosomes and of the
network represents a kind of crystallization process that
is regulated by the amount of chromatin present. This
suggestion also meets with serious objections, for, were
it true, we should expect, I think, to find that the chromo-
somes would assume definite positions with regard to
each other. The evidence shows clearly that this is not
the case, as seen best when chromosomes of different
sizes exist. The arrangement is varied in different cells
of the same individual and in only a few cases do certain
chromosomes lie in a definite position in the equatorial
plate—in the center of the plate, for example, as seen in
the spermatocyte divisions of certain insects. We can
only fall back, therefore, on the evidence, brought for-
ward by Rabl and demonstrated in the clearest way by
Boveri, showing that the position of the chromosomes in
the new division is determined by the position of the
chromatin in the last division, and assume that in some
way the center of the old chromosomes becomes the cen-
ter of the new.
Putting the facts together, they go far towards show-
ing that the central axis of the chromosome is not lost in
the resting nucleus, but remains to become the center of
the next chromosome. Here perhaps we find a clue to the
genetic continuity, or individuality. If we look upon
the spinning process of the chromosome as a process by
means of which its peripheral substance is thrown out
into the nucleus to form the reticulum, and assume that
most of it fails to return the next time the chromosome
becomes distinct, we have an hypothesis in conformity
with many facts at least, and also a view that makes
simpler, perhaps, our interpretation of the meaning of
the process. On this view the materials set free by the
chromosomes remain behind in part when the nuclear
wall is dissolved, and become a part of the cytoplasm of
the cell. In this way chromatin materials set free at
each breaking down of the nucleus reach the cytoplasm,
and in time may come to represent a large part of the cy-
No. 524] CHROMOSOMES AND HEREDITY 457
toplasmic substance. If we look upon the chromosomes
as organs for producing the fundamental organic mate-
rial out of substances absorbed by the eytoplasm—in a
word if we look upon the chromosomes as assimilating
centers of the cell we can understand the enormous in-
crease of chromatin in the early stages of development
of the embryo, and also how in time their products set
free in the cell may come to have a controlling influence
on the reactions and responses of the cytoplasm of the
cells.
Any one who has observed the dissolution of the enor-
mous germinal vesicle will sympathize with such an in-
terpretation. A relatively large part of the nucleus is
thrown out into the cell; for, the chromosomes form a
relatively small part of the entire germinal vesicle.
The impression, often given in popular works on the
cell, that the nuclear sap alone is set free at the dissolu-
tion of the nuclear wall, and that this nuclear sap is
only a watery fluid without significance in the cell, is
probably erroneous. On the contrary, there is set free
not only a fluid, but a large mass of material that may in
part represent some of the nuclear network, and much of
this material at once assumes the same staining capacity
as the rest of the cytoplasm. .
Individuality of the chromosomes means, therefore, in
this sense genetic continuity from cell to cell of a portion
of each of the original chromosomes. This interpreta-
tion will apply whether we consider the chromosomes as
made up of entirely different materials, or of partly dif-
ferent materials, or even if they are all identical in
chemical composition. Let us turn then to the next most
important question. Have we evidence to show whether
the chromosomes are identical in chemical composition
or whether they are different?
We may dismiss at once, I believe, the evidence based
on the similarity of the staining capacities of the chro-
mosomes. With the rarest exceptions they all stain
alike. Such methods as are used are too crude to throw
any light on the question of their possible differences.
458 THE AMERICAN NATURALIST [ Vou. XLIV
The stains that we employ do little more than differen-
tiate basic from acid bodies and in this regard the chro-
mosomes belong to the acid group. Their finer differ-
ences, if such exist, would not appear by the methods
used.
The most striking evidence that can be cited to show
that the chromosomes are different is based on their size
relations. These are constant. Does this mean that the
chromosomes are therefore different? I do not believe
that such evidence is of any value one way or the other.
If the size of the chromosomes is referable to their
genetic continuity, the facts can be accounted for without
recourse to the assumption of chemical difference.
Fortunately we have some evidence from embryology
that has seemed to many embryologists to indicate that
the chromosomes differ in their physiological behavior;
from which we may infer that they differ chemically.
I refer to Boveri’s brilliant experiments with the disper-
mic eggs of the sea urchin.
When two spermatozoa enter simultaneously the egg
of the sea urchin each brings in its own center or aster
from which two centers are formed. These two centers
form a triaster (one being excluded) or a tetraster about
the three pronuclei (two male, one female). When the
nuclei dissolve each sets free its 18 chromosomes, pro-
ducing 18 X 3—54 chromosomes which are distributed
to the three poles of the triaster, or to the four poles of
the tetraster. The distribution is, as a rule, irregular
in the sense that some centers get more than others.
The protoplasm then divides into three or into four equal
parts, the axis of division corresponding with that of the
egg axis as in normal division.
From these eggs embryos develop; many of them are
abnormal, but a few are normal. Normal embryos de-
velop more often from the eggs that divided at once into
three, than from those that divided into four. Boveri
points out that the chance is greater in the three-fold
type that each cell gets at least one set of the chromo-
No. 524] CHROMOSOMES AND HEREDITY 459
somes than in the four-fold type—hence he argues the
greater frequency of normal development.
Boveri’s chief results, however, were obtained by iso-
lating the three blastomeres of the three-fold type and
the four blastomeres of the four-fold type. Under these
circumstances one or two or three of the isolated blas-
tomeres may produce a normal embryo, but, as a rule,
not more than one normal embryo develops, although as
stated, cases of two or three embryos are also found.
This result can be explained on the ground that only
those blastomeres develop normally in which one full
complement or set of chromosomes is present. Boveri
concludes that normal development is dependent on the
presence of at least one set of chromosomes. Hence the
evidence points to the conclusion, he believes, that the
chromosomes are different; and that one of each kind
must be present to insure a normal process of develop-
ment.
That the results are not due to cytoplasmic differences
is shown by the fact that the plane of first division passes
through the axis of the egg, so that each blastomere gets
a part of the different regions of the egg. That the re-
sult is not due to the size of the blastomere is shown by
a comparison with isolated blastomeres of eggs that have
divided normally. Moreover, experiments with fertilized
egg-fragments show that normal development is not de-
pendent on a prescribed size relation petworn the nucleus
and the cytoplasm.
Other objections that have been raised have also been
successfully met by Boveri and I can not but think, there-
fore, that until more valid objections can be found,
Boveri has made good his point.
The experiment of fertilizing non-nucleated fragments
of the egg has demonstrated that a single set of chro-
mosomes suffices to produce normal development. Arti-
ficial parthenogenesis in the sea urchin has also shown
that the single set of chromosomes in the female pronu-
cleus is capable of giving rise to normal embryos. It
follows that as a result of normal fertilization a double
460 THE AMERICAN NATURALIST [Vou. XLIV
set of chromosomes is present in the embryo—two of
each kind of chromosomes—and this fact is of signifi-
cance in heredity.
Boveri has added further evidence in favor of his
conclusion from an experiment in which normally fer-
tilized eggs are put under pressure just as the cleavage
is about to appear. The cytoplasm division often fails
to take place. A single cell may sometimes contain two
nuclei and such cells not infrequently later form poly-
asters. These may cause inequalities in the distribution
of the chromosomes, and the abnormal development that
sometimes follows can be explained in the same way as in
the case of the dispermic eggs. Boveri asks what can
these cases have in common unless it is the inequality in
‘distribution of the chromosomes.
Driesch has argued that, since in the normal develop-
ment the plane of bilaterality corresponds with the first
(Boveri) or second (Driesch) plane of cleavage, the
three-fold or four-fold types may fail to produce this
effect at the right moment. But it is not evident, even
if it is true that a bilaterality exists in the egg, that the
embryo might not still produce it independently of the
cleavage. In the case of the four-fold type an opportu-
nity is, in fact, furnished for the normal relation to ap-
pear, yet this type produces fewer normal embryos than
does the three-fold type. Moreover, the development of
symmetrical embryos for the one-half and one-fourth
blastomeres shows that the egg has remarkable regula-
tory powers in this regard. Again radially symmetrical
embryos have been produced by Herbst in lithium solu-
tions, yet these do not appear in embryos Ga disper-
mic eggs.
This evidence goes far towards establishing in some
form the probability of Boveri’s argument. It seems to
me more cogent and convincing than that brought for-
ward by his opponents. It does not, I think, prove that
the chromosomes are entirely unlike and does not, ob-
viously, prove that each character of the embryo is
: located in a particular chromosome. But the evidence
No. 524] CHROMOSOMES AND HEREDITY 461
makes probable the view that the different chromosomes
may have somewhat different functions, and that normal
development depends on the normal interactions of the
materials produced by the entire constellation of chro-
mosomes.
Boveri himself is far from wsatibing to the chromo-
somes the intricacies of the Weismannian conception.
He has clearly stated that his conception of their individ-
uality does not require that each chromosome represents
a distinct character of the individual, or even an exclu-
sive bundle of such characters. He concedes, that what-
ever it is in them that stands for the characters of the
adult may be distributed to all of the chromosomes in
some species, and that in different species the materials
may be differently assorted.
It should indeed be pointed out that Boveri’s evidence
seems to prove too much for that form of the particulate
theory that ascribes unit characters to chromosomes, for
it indicates, I think, that individual chromosomes do not
in any sense contain either preformed germs or determi-
nants, or unit characters, or even stand for the produc-
tion of particular organs in any sense.
Were this the case we should expect the isolated blas-
tomeres of the dispermic eggs to produce different kinds
of organs, heterogeneously united. It can not fairly be ©
argued in reply to this point that such development
would be a physical impossibility; for, we are familiar
with the fact that teeth, hair, bones, etc., may form in
various teratomata, and this shows that individual
organs may develop independently of the rest of the or-
ganism with which they are normally connected. This
side of the question has not, I believe, been sufficiently
considered by Boveri.
It is true that Boveri has pointed out that embryos
that develop from dispermie eggs are often imperfect or
asymmetrical and interprets this as due to the inequali-
ties of distribution of the chromosomes. His figures,
however, give the impression that the abnormalities are
due to imperfections in the relations of the parts rather
462 THE AMERICAN NATURALIST [Vou. XLIV
than to dislocation of organs as his view in the strictest
sense seems to require. It should not be forgotten that
eggs normally fertilized if kept under unfavorable con-
ditions so that they develop abnormally show similar im-
perfections. Were his results really due to dislocations,
i. e. mal-assortments of chromosomes, we should antici-
pate a far greater mosaic type of development, I think,
than actually appears.
In conclusion we must consider the behavior of the
chromosomes at that period in their existence that has
seemed to most cytologists the most critical time in their
history, especially in relation to their behavior in hered-
ity. I refer to the so-called synapsis, when the total
number of chromosomes becomes reduced to one half the
number characteristic of the body-cells. The most sig-
nificant fact in this reduction is that lke-chromosomes
pair, or unite, as first made probable by Montgomery,
and since confirmed on an extensive scale by several
other writers, notably by McClung, Wilson, Stevens,
Schreiner, ete.
It may appear that we can most easily interpret this
process as due to like materials running together or
fusing in consequence of the likeness of the materials
themselves. But that the process is something more
than this seems probable from the fact that such union
takes place at no other time in the innumerable resting
stages, except at this particular one, just prior to polar-
body formation in the egg, and at the corresponding
period in the spermatogenesis. The actual apposition
of the thread-like chromosomes that has been described
by many observers does not suggest a simple physical
fusion or running into a lump of like materials, but
rather the approach and fusion of definite cell constit-
uents. The line of separation persists for some time in
some species, according to certain observers, and may,
according to Brauer and others, remain evident until the
next division occurs, when the threads again separate to
pass to different parts of the spindle.
The mechanism appears to be such, on this interpre-
No. 524] CHROMOSOMES AND HEREDITY 463
tation, that like chromosomes are at this time separated
and pass into daughter cells. If this is the correct in-
terpretation the process is one of profound significance
for students of heredity.
It is true that in most cases a separation between the
united pairs can no longer be detected and this has been
interpreted to mean that an actual fusion takes place as
complete as when two drops of water unite into one. If
so there would be no grounds left for assuming when the
next division occurs, that the united halves actually sep-
arate again; for the splitting might occur along any axis
of the double chromosome as far as we know. I should
not care to make any dogmatic statements in regard to
this question in the present unsettled state of our knowl-
edge; but whether we assume the separation to be along
the line of union or whether in any other plane the con-
clusion will have, as I said, a deep interest for the stu-
dent of heredity.
There is one additional piece of evidence that may be
cited in favor of the non-fusion interpretation. In some
insects one pair of chromosomes does not enter into
synapsis. These remain apart in the nucleus in some
species or simply touch each other without fusion in
others. In both cases the pair enters the spindle and
its members pass to opposite poles.
Even more remarkable are such forms as Acholla, in
which one large chromosome has as its mate five smaller
ones. None of them fuse in synapsis, but they meet on
the spindle and four go to one pole and one—the larger
one—to the opposite.
It may be argued that these cases show that the ‘‘pur-
pose’’ of the synapsis is only to bring together similar
chromosomes in order that they may be again sepa-
rated. It can not be denied that these cases give a certain
plausibility to this interpretation, yet they are excep-
tional cases, and it is unsafe to generalize from them to
other chromosomes that we know to behave differently.
Moreover, this method of ‘‘touch and go’’ appears to be
so much simpler than the elaborate changes involved in
464 THE AMERICAN NATURALIST [Vou. XLIV
synezesis, that one may well ask whether synezesis may
not have a deeper significance than the mere apposition
of like chromosomes. In fact the process seems well
suited to bring into close and intimate fusion the pairs
of chromosomes instead of simple apposition as appears
in the sporadic instances cited above. The situation calls,
at least, for a suspension of judgment until we have more
evidence.
The number of chromosomes in closely related forms
presents one of the most puzzling problems when we at-
tempt to apply the chromosome view to the facts of
heredity. The case of the thread worm of the horse, As-
caris megalocephala, is the best-known case. In some
localities the worms have four chromosomes for their
full number, in other localities only two. The animals
are identical externally, and occasionally where both
forms exist crosses occur. In such hybrids three chro-
mosomes are found in the embryo, but unfortunately no
adult worms have as yet been seen with three chromo-
somes. Such a worm would offer an exceptional oppor-
tunity to study the reduction problem. In other groups
similar variations in numbers are known between closely
related species. For example, one of the phylloxerans
has 44 and another 12 chromosomes, yet the two species
differ only in minor points, and every structure in one
has its counterpart in the other. If the chromosomes are
the bearers of the hereditary characters how can such
facts be interpreted?
If we think of each chromosome in the one species as
containing the unit characters of a leg, or a wing, or an
eye, how are the same characters distributed in the other
species? Evidently a complete redistribution of such
units must be conceived. If genetic continuity is to be
extended also to the origin in time of the unit characters
in species, it seems to me inconceivable that so vital a
question as the assortment of these characters should so
readily change in closely similar, and probably closely
related species. Difficult as it is to interpret this rela-
tion, the simplest view would be to assume that it makes
No. 524] CHROMOSOMES AND HEREDITY 465
no difference how the chromatin is assorted in the
chromosomes, so long as the sum total of the materials
is present.
From this point of view the individuality of the chro-
mosomes is a matter of secondary importance; for, the
same or equivalent material may be represented by two
or by forty chromosomes. Individuality or genetic con-
tinuity (i. e., ontogenetic not phylogenetic) has no
further significance, from this standpoint, than that it
insures for each species the transmission to all the cells
of the body of a given amount of materials or possibly a
definite amount of all the different kinds.
We may next proceed to examine into the relation of
the chromosomes in Mendelian inheritance from the
point of view reached in the preceding discussion.
CHROMOSOMES AND MENDELISM
. It has become generally accepted by students of Men-
delian inheritance that some kind of ‘‘segregation’’ is
the key to the numerical results that play an all-impor-
tant part in the Mendelian theory of heredity. The dis-
covery that there occurs in the formation of the germ-
cells a process that supplies the machinery by means of
which segregation might take place has aroused expec-
tation to a high pitch of interest in the application of the
observations of cytology to the conclusions in regard to
Mendelian segregation. It is true that there is much
diversity of opinion as to the value of cytological study,
in its present imperfect state of development, to Men-
delism, and this divergence relates unfortunately to the
very nature of the processes involved.
Mendel realized that the numerical proportions that
appear in the second hybrid generation could be ex-
plained, if, in the formation of the germ cells or gametes,
a separation of the constituent elements, or characters of
the hybrid occurs. These paired characters that separate
Bateson has called allelomorphs.
A process takes place in the germ-cells, at- the
so-called maturation divisions, that may possibly offer _
466 THE AMERICAN NATURALIST [Vou. XLIV
a clue as to how the paired characters in the germ cells
of the hybrid separate. Prior to this division there are
two chromosomes of each kind; one member of each
pair being maternal in origin and the other paternal.
The members of each pair come together just before
maturation division, reducing the number of chromo-
somes to half. Later these paired chromosomes divide
so that each germ-cell gets one half of each pair.
Sutton first pointed out in 1903 that if each character
that mendelizes is carried by a particular chromosome
the mechanism of reduction gives an explanation of the
way in which there may come to be two kinds of germ
cells with respect to each particular pair of characters.
This hypothesis has been championed by Wilson in
1903, and later by Boveri in 1904.1. If we analyze the
facts further we find that the hypothesis requires in
order that pure gametes are to be formed by the hybrid
that each particular character, or whatever it is that
produces the character, be confined to a single chromo-
some; otherwise the separation will not be complete and
pure gametes will not be formed. Do the facts of reduc-
tion fulfil this condition?
When the reduction in the number of the chromosomes
takes place we find that the homologous pairs of chro-
mosomes fuse completely, so far as we can judge by our
modern methods of technique. Observation gives no
evidence in most cases that the chromosomes only ad-
here side by side, but on the contrary conjugation ap-
pears to be a complete fusion, and if this is what really
takes place, what guarantee is there that subsequently
the members of a pair will separate along their line of
fusion? It seems all the more remarkable that such a
process should take place, if, as is often assumed, the
separation division is not the first, but the second divi-
sion of the paired chromosome. In other words it is ad-
mitted that in such cases the first division is at right
In 1902 Boveri referred to a possible relation between reduction and
inheritance in hybrids, but he did ‘not point out how this idea could be
applied to explain the numerical results of Mendelism.
No. 524] CHROMOSOMES AND HEREDITY 467
angles to the plane of union, and that only at the second
division does separation or segregation occur. In fact
the assumption of separation is largely gratuitous, and
is the outcome of certain theoretical postulates of Weis-
mann’s theories—postulates that rest in part on ques-
tionable evidence.
All that we really know is that in some cases two longi-
tudinal divisions of the chromosomes occur,? whose rela-
tion to the plane of fusion is largely hypothetical. If,
however, it be assumed that the chromosomes simply
come to lie side by side (or even end to end) and later
separate the process of synapsis, as it is called, is
merely ‘‘touch and go’’ and has no deeper significance.
If, on the other hand, it be assumed that the synapsis is
a true fusion of the combining elements, there are no
reasons to suppose that the chromosomes separate later
into their constituent parts. The expectation is rather
that once completely fused they do not necessarily sepa-
rate at the plane of fusion to give the pure elements that
combined.
It is, however, the assumption that the chromosomes
do separate along their line of union that has appeared
to some writers to have important bearing on the theory
of Mendelian theory of pure gametes. Let us therefore
assume for the moment that the separation takes place
in this way. Since the number of chromosomes is rela-
tively small and the characters of the individual are very
numerous, it follows on the theory that many characters
must be contained in the same chromosome. Conse-
quently many characters must Mendelize together. Do
the facts conform to this requisite of the hypotheses?
Tt seems to me that they do not. A few characters, it is
true, seem to go together, but their number is small, and
it is by no means evident that their combination is due
to a common chromosome. It is true that in no one
species do we know much concerning the behavior of
many characters, but so far as we do know them there
2For the sake of simplicity I have left out of account here the possi-
bility of end-to-end union.
468 THE AMERICAN NATURALIST [Vou. XLIV
is no evidence that they Mendelize in groups commen-
surate with the number of chromosomes. In two cases,
in fact, viz., in Pisum and in Antirrhinum it appears that
the number of the characters that have been shown to
Mendelize separately is greater than the number of their
chromosomes.
This has seemed a fatal objection to the chromosome
view, but it may not be so, as Spillman has argued, so
long as it has not yet been shown that all of the domi-
nant characters may be present at the same time. But
even admitting this possible way of eluding the objec-
tion, the other point raised above concerning the ab-
sence of groupings of characters in Mendelian inheri-
tance seems a fatal objection to the chromosome theory,
so long as that theory attempts to locate each character
in a special chromosome. We shall have occasion to re-
turn to this point later.
In recent years most workers in Mendelian inheri-
tance have adopted a new method of formulating their
theory. Characters that Mendelize are no longer allelo-
morphic to each other, but each character has for its
pair the absence of that character. This is the presence
and absence theory. We can apply this hypothesis to
the chromosome theory. For examples, let us assume a
new variety or race arises by the loss of a character
from that chromosome that has heretofore carried it. The
chromosome still remains in existence, since it may carry
many other characters besides the one that was lost,
and it becomes in the hybrid the mate of the one still re-
taining that character. If now separation occurs, two
classes of germ-cells result, one with and the other with-
out the character; and the observed numerical propor-
tions follow. There is nothing in this assumption that
meets with any greater difficulty on the chromosome
separation hypothesis than on the earlier view of paired
allelomorphs, but it meets with the same difficulties, and
as an assumption is neither more nor less in accord with
the postulated mechanism.
= More recently, still another interpretation has been
No. 524] CHROMOSOMES AND HEREDITY 469
suggested by Shull and by Spillman. It is a quantita-
tive conception, and I shall try to point out some of its
applications to the chromosomes.
Let me recall once again the familiar fact that in ani-
mals and plants two homologous chromosomes of each
kind are present in every cell. This gives the diploid
number. One of each kind suffices to produce the char-
acter in some cases, but each is nevertheless present in
double. We might think of the doubleness as a sort of
reserve and the double group be conceived as a ‘‘mechan-
ism of safety.’? That the double number is not always
necessary for the formation of the characters is shown
in embryos that develop from non-nucleated fragments
of eggs. These embryos have all the characters peculiar
to their species. The importance of the double set is
illustrated, however, in certain hybrids. The best case —
is that of the hybrid between horned and hornless races
of sheep. The male hybrids from this union have horns,
the female hybrids lack horns, irrespective of the way in
which the first cross was made, 2. e., the results are the
same whether the mother was E and the father
hornless, or the mother hornless and the male horned.
Bateson interprets this to mean that one dose of horns
in the male hybrids suffices to call forth horns; but one
dose in the female hybrids is insufficient to call forth
horns. In terms of chromosomes this may mean that
one horn-bearing chromosome suffices in the male to call
forth horns, but in the females one chromosome is not
enough.
When these hybrids are inbred they produce in the
second generation four kinds of individuals, horned
males and females; hornless males and females. The
numerical results appear to coincide with the assump-
tion made above in regard to the number of doses of
chromosomes necessary to call forth horns in the two
sexes. For in the second generation there will occur a
certain number of combinations in which females will
contain two doses of horns and these females should be
horned.
470 THE AMERICAN NATURALIST ~~ [Vou. XLIV
The case of color blindness in man appears to follow
the same rule, for here also females may transmit the
character without developing it, while males, if they have
it at all, develop color blindness. One dose of color
blindness in males makes the male color blind; one dose
in females is insufficient. The rarity of color-blind fe-
males is explicable on this view.
These results may be significant for the chromosome
hypothesis since the interpretation seems to imply that
the amount of a given material, or chromatin, perhaps,
is an important element in the determination of the de-
velopment of characters. If the interpretation is cor-
rect it means that a character will not develop even
when its primordia or forerunners are present, unless a
sufficient amount of that material be present. And, on
the other hand, in other individuals a smaller amount of
the same material suffices to call forth the unfolding of
a given structure.
The same interpretation seems to have a wide applica-
tion to the characters of the first generation of hybrids,
and in all heterozygous individuals that are in nature
identical (i. e., heterozygous) with the first generation
hybrids. It is known that in several cases the dominant
character does not reach its full development in the first
generation, as Correns showed for Mirabilis Jalapa.
Such cases can be explained on the ground that one dose
is not enough. The reappearance in the second genera-
tion of individuals with the full dominant character is
in harmony with this assumption, for in one fourth of
the individuals two doses of dominance are expected.
In mice, too, the heterozygous form between black and
chocolate often shows black or chocolate areas in the
fur, and in the same mouse a region may be at first black
and later chocolate, or vice versa. It appears that the
condition of the mouse at the time when the molt takes
place determines whether the hair contains the one or
the other pigment in excess. Thus external conditions or
internal-states may regulate dominance in hybrid forms.
Such facts lead to a consideration of how far quanti-
No. 524] CHROMOSOMES AND HEREDITY 471
tative relations are factors in heredity, and how far the
chromosomes support such an interpretation. If, as we
have seen, the development of a character depends on
the amount of a given material rather than on its pres-
ence or total absence as the theory of pure gametes de-
mands, may not this view give an interpretation of the
rôle of the chromosomes in inheritance?
Let us see where such an interpretation leads. By
means of diagram A, I have tried to indicate one way
in which a quantitative interpretation of the facts of
Mendelian inheritance might be explained. In the hybrid
the pair of fused chromosomes, representing the pres-
ence and absence of a character, is represented by the -
black and white semicircles fused together. Should
their separation occur along the line of fusion (first line)
as demanded by the theory of pure gametes, there will
result after two divisions two chromosomes bearing
the positive character (or briefly the black chromo-
somes), and two without (or the white chromosomes).
These are represented for the egg in the upper line by
the four semi-circles; and the similar cells for the male
by the four similar semi-circles in the line below.
Chance combinations will give three classes of individu-
als in the proportion of 1:2:1; or three with the domi-
nant to one with the recessive character.®
But should the pair of chromosomes fuse and not
separate at the line of fusion, the results are shown in
the second line, where the intersecting lines indicate
the plane of division. Again four classes of gametes
result, as shown in the upper line. If the same sort of
division occurs in the male, and fortuitous combinations
result, there will be the same three classes of individuals
as before, which gives the ratio of three dominant to one
recessive.*
The only division that will not give this result is that
2 In this scheme when one of the two chromosomes of the pair is black
the combined action is black.
“It is assumed here that when as much or more than the volume of one
member of the pair is black the result is blac
472
THE AMERICAN NATURALIST [ Vor. XLIV
4m Ga oA
V V P Y
' Ta D
P U Y
Gy \'4\ `
PV JI
Ga \i )\ &
oe oa
a \i )\
Ø Y Y WV
when the planes of division lie exactly at 45 degrees to
the plane of fusion, as shown in the third line. Here the
results give 11 dominant to 5 recessive, but this is so
near the three to one proportion that it offers no serious
drawback to the result when we consider how seldom
this division will oceur.
the two remaining lines show the results of back-cross-
No. 524] CHROMOSOMES AND HEREDITY 473
ing between the hybrid (F,) with the recessive (fourth
line); and with dominant (fifth line). They give the
expected proportions.®
In all of the preceding cases except the first the
gametes are not pure, as a rule, but nevertheless pro-
duce two classes of individuals that may be sharply de-
fined. This scheme seems to work as well as the pure
gamete assumption; it avoids certain difficulties encoun-
tered by the latter; and appears to explain further a
class of cases inexplicable on the pure gamete hypothe-
sis; namely the graded series of forms so often met with
in experience and so often ignored or roughly classified
by Mendelian workers.
Again, for simplicity it has been assumed that varie-
ties or races lacking a character lack entirely. the kind
of activity that calls forth that character. But there is
no need to make this limitation. If in some cases the
lack of character may in reality be due to total absence
of action, there are other cases which can be explained
on the chromosome basis if we assume that the absence
of a character is due to incomplete or insufficient activ-
ity of its chromosomes varying from 1 to 50, to put the
matter graphically. Let us assume 25 per cent. of activ-
ity takes place. Such an individual paired to a’ domi-
nant will give dominance in the first generation (due to
the 50 per cent. of the dominant plus 25 per cent. of the
recessive). Chance splitting of the fused chromosomes
after synapsis in the hybrid will give two classes of
gametes, but one class will contain numerically more than
50 per cent. of character-forming materials. Conse-
quently there will be more individuals of the dominant
race than the theory of pure ail and equal division
demands.
The converse case is also oe of consideration. If
one individual is just able to produce a given color or
material by the combined activity of its two chromo-
somes, but no more than just able to do so, and the other
5 Provided when more than half of a chromosome of a pair is black the
result is black.
-~
474 THE AMERICAN NATURALIST [VoL. XLIV
individual totally lacks all power, the first hybrids will
also fail to produce the character. Their chromosomes
combined and divided at random in the germ cell will
produce a much larger number of gametes that fall be-
low the standard than of those that rise to a point suffi-
cient to give the character when combined—in conse-
quence the recessives will be greatly in excess.
These considerations may seem to throw light on the
question of potencies of different individuals—a question
that is coming more into the foreground. We can see
from the point of view here suggested how individuals
alike externally may differ very greatly in their power
to transmit their peculiarities to hybrid offspring.
This conclusion is especially applicable to cases where
the full development of a character can only appear
when two groups of chromosomes (to take the simplest
case) are necessary to produce a character; or, to take the
more extended view, when excessive amounts of chro-
matin must be present. It is now well established that
certain races lacking a character nevertheless dominate
in the first generation when crossed with a race possess-
ing a character. In such cases the failure of dominance
may be due to insufficient chromatin of the positive kind
rather’ than due to an inhibiting factor as sometimes
assumed,
As regards blending, it is evident that this rela-
tion must result from the combined action of the two
parental contributions to the hybrid; the blending is the
sum of both effects. Such cases differ from Mendelian
cases in the first generation only in that one influence
does not exclude the other. In the second generation
separation into two classes of individuals does not occur,
but a great variety of forms appear: Nevertheless the
individuals may show a tendency to group around the
two parental and the hybrid classes, as Castle has shown
for long and short hair. In this sense blended inheri-
tance shows gradations into alternate inheritance. The
chief difference between the two, I repeat, is found in the
compatibility of the contrasted characters. So far as
No. 524] CHROMOSOMES AND HEREDITY 475
the chromosomes are concerned the results need not be
referred to any special kind of fusion of the combining
elements, but simply to the way in which the effects be-
come patent. Alternate inheritance and blended in-
heritance appear only to be extremes of the same process.
This brings us to the inheritance of the spotted con-
dition, a class which has been a serious difficulty on the
assumption of Mendelian dominance and segregation of
pure characters. The most striking case is that of
spotted animals or striped plants. Some regions of the
body are colored, other regions white, i. e., they lack
pigment. On the assumption that the individual has the
capacity to produce pigment the presence of white spots
is inexplicable; on the assumption that the individual
lacks the power to produce pigment the colored spots
are inexplicable. A spotting factor is therefore assumed
whose presence accounts for spots. Its allelomorph is a
uniform coat whose presence does away with spots. A
more refined juggling would be difficult to imagine, espe-
cially when the presence of color is explained by the
presence of an enzyme and a color producer, and its
absence to the lack of one of these. Yet after appealing
to a purely physiological principle to explain ‘color
versus no color, the explanation is thrown overboard in
the case of spotted animals and a mystical spotting fac-
tor is set up as an explanation. The humor of the situa-
tion grows when one thinks that the spotting factor may
produce a few white hairs on the tip of the tail, or a coat
nearly entirely white. To be logical there should be as
many spotting factors as there are hairs on the body.
It has been shown that the spotted condition does not
follow by simply crossing a uniform color and an albino
—unless that albino has been derived from spotted an-
cestors. Hence spotting is not due to combinations of
this sort, but is due to a condition peculiar to certain
races. How can we interpret this peculiarity? The
great difficulty of explaining this class of cases must be
admitted, but I think that a possible interpretation may
be found in the following direction, although I am far
476 THE AMERICAN NATURALIST [Vowu. XLIV
from wanting to urge that it is the only possible inter-
pretation. The absence of a character, color in the pres-
ent instance must be due to local conditions; certain
regions are like the hornless female hybrid sheep. It
is well known that injuries to the skin may cause the ces-
sation of formation of colored hair and the production
of white hair. Similarly in colored animals, certain
regions are more prone to lack pigment than other re-
gions. In rodents for example, the belly, the tip of
the tail and the forehead seem to be such regions even
in animals that would be classed as uniformly colored.
It follows that if in certain races these regions are par-
ticularly deficient in their power to produce pigment a
spotted race will arise. Crossing with an albino race
does not increase the extent of the spotted area in the hy-
brid. On the contrary, if the white animal has been de-
rived from a race uniform in pigment production in these
regions the hybrid will be uniform, i. e., not Bpostes at
all, although one parent was spotted.
It may appear that this view has simply introduced the
spotting factor in a new guise. Ina sense this is true,
but it recognizes a condition that is ignored by those
who make use of a spotted factor, for it rests on the
assumption that whether pigment develops in certain re-
gions depends not only on whether pigment producing
factors are present or absent in the germ cells, but on
the modifications of such inheritance by local conditions.
My conclusion is, moreover, of a piece with our general
knowledge of development of different organs of the
same embryos.
Why, it may be asked, can not the spotted character be
explained on the assumption of weakened power in these
spotted races to produce color; or why is it not due to
loss of chromosomes in the satis blastomeres of the germ
cells in certain regions?
The first alternative must be rejected, I believe, for
were the power of color production weakening in spotted
animals, the ratio being lower than 50 per cent., we should
still have to invoke local action to account for the results.
No. 524] CHROMOSOMES AND HEREDITY 477
Moreover, there is no evidence that color production is
less intense here.
The other alternative can be answered on more general
grounds. If Mendelian characters are due to the pres-
ence or absence of a specific chromosome, as Sutton’s
hypothesis assumes, how can we account for the fact that
the tissues and organs of an animal differ from each
other when they all contain the same chromosome com-
plex. Bateson has called attention to this weakness of
the single-chromosome-single-character hypothesis. For
on such a view the chromosomes should be sorted out in
the soma until each region gets its proper kind. The
facts are the reverse. However important therefore the
chromosomes are in transmitting the full quota of heredi-
tary traits, we must be prepared to admit that the evi-
dence is entirely in favor of the view that the differentia-
tion of the body is due to other factors that modify the
cells in one way or in another. This consideration is, to
my mind, a convincing proof that we have to deal with
two sets of factors—the common inheritance of all the
cells to produce all the kinds of tissues and organs in the
body, and the limitation of that property in the course
of development. If the former is due to the chromo-
somes and the unspecialized parts of the cytoplasm, the
latter may be due to the local changes that the relation
of the parts to each other calls forth. It might even
be argued that since in the development we find no evi-
dence of a sorting out of the chromosomes that produce
special parts, the individual chromosomes can not stand
each as the representative of those parts, but rather that
each part needs the entire set of chromosomes for its
normal life. However tempting such an argument may
be for those who have reached on other grounds the con-
clusion that this is the more probable interpretation of-
the chromosomes, the argument will not appear conclu- —
sive to those who do not accept such a general standpoint,
for they may justly claim that we know too little about
the possibilities of chromosomal behavior to make this
478 THE AMERICAN NATURALIST [ Vou. XLIV
sort of a demand of them. The consideration is never-
theless, I think, worth consideration.
The most serious, and probably fatal, objection to the
quantitative view outlined above is found in the later
possibilities of the mixed chromosomes. If the longitu-
dinal division is fortuitous in the synaptic pair it must
also be assumed to be fortuitous in the later splittings of
the same chromosomes in the embryo. The results
would give a mosaic of cells in some of which one and
in other cells another character will predominate. We
should expect therefore a sort of piebald or chimaera
type to result. The difficulty is not minimized by refer-
ring the results to all of the chromosomes instead of to a
single one.
Unless we refer the problems of heredity to principles
apart from a material basis our only hope at present of
a scientific solution of the problem is to rely on such a
basis. There are three ways, however, in which we may
make use of such a physical material conception of ‘‘seg-
regation.’’ First, by postulating material particles in
the chromosomes of the germ cells qualitatively different
—particles that are sorted out at the reduction period.
Our analysis has shown that there are serious difficul-
ties for this interpretation. Second, by postulating a
quantitative factor as the basis of segregation; here also
difficulties are met with. Third, by assuming initial dif-
ferences in the germ cells of the hybrids due to the
same kind of differences that become patent in the
development of the embryonic organs where the re-
sults are not referable to segregation of chromatic ma-
terials, but due to regional differences or state of equi-
librium—the result of reactions between the cells. Here
it seems to me we find the most promising direction in
which to look for further light on the subject. For ex-
ample, the formation successively of brown, yellow and
black pigment by the follicle cells of a gray mouse sug-
gests that a similar process may take place in the germ
cells of hybrids. In the somatic cells no one supposes
that the differences are due to loss of chromatin, or to a
No. 524] CHROMOSOMES AND HEREDITY 479
segregation, otherwise, of materials. On the contrary,
the presumption is in favor of the view that the effects
are produced not by segregation, but by the relation of
the cells to each other, or to the whole. If this compar-
ison be admitted, it follows that at some stage in the
history of the germ cells of the hybrid similar effects
may take place in regard to each kind of the inherited
qualities (not characters). In this connection it should
be recalled that the germ cells of the hybrid have had a
long history before maturing. If the chromosomes are
the essential elements in producing or maintaining the
material constitution of the cells there has been an abun-
dant opportunity for the chromosomes to have produced
general effects of this kind. The way in which the cells
react will depend on the changes that the chromosomes
have produced in them. In other words, at some period
in their history when the germ cells have become, as it
were, hybrid throughout they develop one or another of
each of the alternate possibilities to a greater or to a less
degree. Since the same sort of process occurs in groups
of somatic cells where it results from the responsive ac-
tion of the parts on each other, so let us suppose in the
germ cells of the hybrid a similar relation determines the
fate of its different potentialities.
Our general conclusion is, therefore, that the essential
process in the formation of the two kinds of gametes of
hybrids in respect to each pair of contrasted characters,
is a reaction or response in the cells, and is not due to a
material segregation of the two kinds of materials con-
tributed by the germ cells of the two parents. The reac-
tion differs in the germ cells of the hybrid from that of
either of the parental types because the material basis
of the germ cells differs owing to its dual origin. The
results are due, however, to difference in reaction, and
not to a separation of mixed materials. The general
point of view that underlies this conclusion is epigenetic,
while the contrasting view, that of separation of mate-
rials, is essentially one of preformation.
480 THE AMERICAN NATURALIST [ Vou. XLIV
CHROMOSOMES AND SEX.
In recent years two converging lines of evidence have
led the most sanguine of us to hope that before long we
shall know, in part, at least, the answer to the outstanding
riddle of the ages, the determination of sex. These two
lines of research are the experimental study of sex in-
heritance, and the microscopic study of the germ cells.
Both have led to the conclusion that sex is not, as has
been so often supposed, determined by the external con-
ditions to which the parents, or the eggs, or embryos are
subjected, but that there exists an automatic process in
the egg and sperm by which equality of the two sexes is
attained.
Before I bring this evidence forward, I must stop for
a moment to point out how the idea that sex is deter-
mined by external conditions arose, for this view is by no
means defunct. In fact it is a widely current belief at
the present time. One might, in fact, appear to justify
himself in holding such a view, not only by quoting the
names of those who have advocated it or still maintain
it, but even by referring to a considerable number of ex-
periments that have been claimed to be in favor of such
an interpretation. :
Landois stated in 1867 that he could produce male or
female butterflies at will by regulating the amount of
food of the caterpillars. Similar statements were made
later by others; but the futility of the experiments be-
came manifest when it was found that the character of
the sexual organs is already determined when the cater-
pillar hatches from the egg.
It has been claimed that the sex of the frog could be
determined by the quantity of food, or by the kind of.
food supplied to the tadpole. More extensive work has
disproven completely this statement also.
Statistical studies, especially those of Diising, are
often cited to show that in man, and in some of the
domesticated animals, the nourishment of the parents
affects the sex of the offspring. But here again other
statisticians have found evidence of the opposite results.
No. 524] CHROMOSOMES AND HEREDITY . 481
The careful experiments of Cuénot and of Schultze on
mice have positively shown that no such relation exists
in these animals.
There are two groups of animals that seemed Fas a
long time to furnish evidence in favor of the view that
sex is determined by the environment. I must refer to
these in more detail.
The plant lice, or aphids, produce throughout the sum-
mer by means of parthenogenesis a series of partheno-
genetic females. In the autumn, when the food begins to
fail, there appear males—and sexual females. If the
aphids and their food plants are brought into the green
house the males and sexual females may not appear, but
the animals go on reproducing by parthenogenesis. It
seems, therefore, that external conditions determine the
appearance of males and are therefore sex determining,
since the parthenogenetic forms are ranked as females.
It has become apparent in recent years that these re-
sults have nothing to do with sex determination in the
sense that external conditions determine the production
of males or females. The results show that external
conditions cause the cessation of the parthenogenetic re-
production and the beginning of sexual reproduction,
i. e. the appearance of males and sexual females.
Whether the one, or the other, seems not to be deter-
mined by the environment, but to some internal mechan-
ism to which I shall refer later.
In the rotifer, Hydatina senta, Maupas claimed that
temperature determines sex. Later Nussbaum tried to
show that food conditions determine sex in this animal.
Still more recently both views have been disproven. It
has been shown in the first place that here, as in the
aphids, the external conditions affect the life-cycle in
such a way that parthenogenesis ceases and sexual re-
production begins. Recently A. F. Shull has determined
that if the animals are kept in old culture water, i. e.,
water in which the food has been kept—parthenogenesis
goes on indefinitely. At least nineteen generations of
purely parthenogenetic individuals have been reared.
482 THE AMERICAN NATURALIST ~~ [Vou. XLIV
But if at any time individuals are taken out of this cul-
ture medium and put into spring water, males and sexual
females appear. By diluting the spring water with
varying amounts of culture water the number of sexual
forms that appear is directly proportional to the dilution.
In this animal the individual that produces the male
eggs is the same individual that produces the sexual egg.
If she is early fertilized by a male, her eggs produce
sexual females. It is clear here that external condi-
tions change the cycle but do not determine sex. This
brief review will suffice to clear away the traditional
evidence supposed to support the view that sex is deter-
mined by the environment.
Let us pass now to the results that seem to show that
there is an internal automatic mechanism that regulates
the production of males and Tomales I shall take up
the botanical evidence first.
Correns?’ experiments with two species of Bryonia,
may be examined. Bryonia dioica is diœcious; B. alba
monecious. Correns’ main experiment shows that when
dioica 2 is crossed with alba 3, all of the offspring are
females, but when alba 2 is crossed with dioica 3, half
the offspring are male and half female. The results can
be explained by three assumptions. First that the male
condition dominates the female, second that the dicecious
condition dominates the monoecious; third, that the fe-
male is homozygous in regard to sex and the male heter-
ozygous.
These conclusions are opposed to the interpretation of
other workers that make the female the dominant condi-
tion. It is also not clear from G. H. Shull’s recent work
on a more extensive scale that the dicecious condition can
be assumed in general to be dominant. :
Whatever the correct interpretation may be, these facts
show at least that by treating sex as a character that
segregates in the gametes, as Mendelian characters in
general are assumed to do, the results can be accounted
for, provided one sex is assumed to be always heterozy-
gous and the other homozygous.
No. 524] CHROMOSOMES AND HEREDITY 483
The experiments of Elie and Emile Marchal on dic-
cious mosses are equally interesting. They used species
with separate sexes. When spores from a single capsule
are sown some produce female, others male protonemata.
The sporophyte generation that produces the spores has
arisen from a fertilized egg; the formation of the spores
is a non-sexual process. The sporophyte contains the
full number of chromosomes, and this number is reduced
to half in each spore, not by union of chromosomes, but
by halving the total number.’
The protonemata or gametophytes produce the male
or the female organs separately. Fragments of a pro-
tonema regenerate a new individual having always the
same sex, under all the possible external conditions to
which the Marchals subjected them. Obviously the sex
of the protonema once determined can not be changed,
and the presumption is in favor of the view that the sex
of each spore is determined at some time in its forma-
tion.
The tissues of the sporophyte itself should contain the
potentiality of both sexes. Owing to the power of re-
generation possessed by this tissue, it is possible to test
such a view. Pieces of the sporophyte regenerate pro-
tonemata—each thread arises from a single cell of the
piece; a cell presumably having the full number of chro-
mosomes. These regenerated protonemata produce
moss plants that are either male, or female, or herma-
phroditic. They seem to be all potentially hermaphro-
dites, but in some plants only the male organs develop—
especially those that first appear; in other plants only
female organs. If the suggestion just hazarded is cor-
rect, namely, that all the plants are hermaphroditic, and
the males and females are due to the failure of the other
sex to develop, we raise a large issue; namely, whether
males and females may not in general be potential her-
maphrodites with only one sex developed, or whether the
sexes are separated into pure male and pure female
€ Although union may have a the weila in number as in ordi-
nary synapsis in plants and anim
484 THE AMERICAN NATURALIST [Vou. XLIV
forms, as is assumed in so many of the most recent spec-
ulations concerning sex. This topic will come up later
for fuller consideration.
As I said, the presumption is that the regenerated
protonemata from this sporophyte have the diploid
number of chromosomes, and when the spores are formed
the number is reduced. Have the sex characters sepa-
rated when the chromosomes are reduced? We have no
means of knowing, but two important points should be
noted: first, that the male or the female is produced with
the reduced number of chromosomes present; second,
that an approach to the same result is reached in the re-
generated forms with the entire number present. Sex
here is not connected with the half number, or the whole
number. Any attempt to solve the problem of sex in the
mosses along these lines must assume that some unknown
or unseen chromosomal element is separated at the time
of formation of the spores.
Furthermore, since hermaphroditic species of mosses
and ferns produce both male and female gametes on the
same plant that has the reduced number of chromo-
somes, it would be necessary to assume in such cases that
some kind of chromosomal separation takes place in dif-
ferent regions of the same protonema to give rise to
male or to female organs. The only other alternative
would be to assume that the kind of gamete formed,
male or female, is determined by the regional differences
in the protonema or prothallium, and that no separation
of chromatin precedes this effect. If such effects can be
produced in this way, may it not be that similar proc-
esses occur in the unisexual species? I shall return to
this topic again.
Blakeslee’s brilliant experiments with moulds also
bring out many important points connected with sex de-
termination, although nothing is known as yet concern-
ing the changes in the chromatin. He finds in Phycomy-
ces that some mycelia are male (or — strains as he calls
them) and that these produce non-sexual spores of the
same sex indefinitely. Other mycelia are female (+
No. 524] CHROMOSOMES AND HEREDITY 485
strains) and produce only female spores. Male mycelia
will not conjugate with mycelia of the same sign, but
readily with the female mycelia. In fact, their sexual
behavior is the only way of distinguishing the two kinds
of mycelia. On the other hand, the sexual spore or
zygospore produces a sporophyte that in turn produces
spores; some of which are male, others female.
In striking contrast to this case is that of Mucor
mucedo. Here also male (—) or female (+) mycelia
are found which unite to form the sexual spore. This
produces the sporangiophore bearing a sporangium
whose spores are all of one or of the other sex, i. e.; a
the spores from the single sporangium give rise to malés.
all the spores from another sporangium gave rise to fe-
males. Despite the fact that the zygospore is formed by
the union of the two mycelia, male and female, the spores
are not mixed, but represent only one sex. Blakeslee
points out that this is the same condition found in diœ-
cious flowering plants, such as the Lombardy poplar,
when one seed gives rise to a male tree, another seed to
a female tree. In these cases the evidence points to the
view that there is no separation of sex units, but a sup-
pression of one sex or the other. In other words that the
basis of sex is the hermaphrodite condition and the uni-
sexual form is due to the suppression of one of the dual
possibilities, and not to a separation of unit characters
that stand for male and female.
Let us next turn to the experimental evidence in the
animal kingdom. Since the experiments of Doncaster
and Raynor on the current moth, Abraxas grossulari-
ata, bid fair for years to come to occupy the foremost
place in speculations concerning sex I shall bring for-
ward this evidence first.
This species has a rare sport known as Abraxas lacti-
color. No intermediate forms between the two exist and
none arise from crossing. In nature female specimens
only of laticolor have ever been found, although males
have been produced artificially by suitable combinations,
as will be seen below.
486 THE AMERICAN NATURALIST ~~ [Vou. XLIV
No less than four hypotheses have been already ad-
vanced to explain these facts. Doncaster assumed, at
first, that each sex produced male and female gametes;
that in the first hybrid generation the male gametes bear
the grossulariata character and the female the lacti-
color; that in the male no such coupling occurs. Bate-
son and Punnet simplified this hypothesis by assuming
that the female is heterozygous for sex, the male homo-
zygous; that femaleness is dominant to maleness; that
in the hybrids the character for femaleness and that for
grossulariata repel each other so that each germ cell
gets one or the other. The results are summed up in
Table I.
TABLE I
Parents. | Constipation. Gametes. Ofepiiing:
i Lact. female LLỌ3 | LỌ, LZ | GLO = gross. female
Cross 1 Gross. male GGS 3 Ge, GZ | GL 3 = gross. male
GL? 3 = gross. female
Cross 2 Heterozygous female| GL? 8 ae , ve LL 9 g=lact. female
Heterozygous male GLS 3 Lg | GL 3=gross. male
isis 3 = gross. male
LỌ $= gross. female
Lact. female ELS T | EO, Le UL Š ĝ = lact. female
Cross 3 Heterozygous male GL? 2 G3, Let PS n
TLS ĝ& = lact. male
Úra i cong gi female!) GLO S | LQ, Gg | LL? #=Iact. female
Lact. LL3g | Lå, LS | GL g=gross. male
Castle pointed out that Wilson’s sex-hypothesis, that
two X chromosomes stand for femaleness and one X for
maleness, will not explain the case of Abraxas, but that
by the hypothesis of one X standing for femaleness and
no X for maleness, the results can be explained; pro-
vided Bateson’s assumption of repulsion is also em-
ployed. Thus if in the Bateson-Punnett table (above)
the male signs are omitted, and X put in for the female
signs, the results just stated follow, as the next table
shows. It will be observed that Castle has simply omitted
the male and female signs and substituted X for female-
ness. When it is absent the male is assumed to develop.
No. 524] CHROMOSOMES AND HEREDITY 487
_ TABLE m
a | Penmaes: Han Constitution. | Gametes. _ Offspring.
Conant Lact. female LLX LX, L GLX= gross. lenais
Gross. male GG G, G GL = gross. male
GLX = gross. female
Cross 2 | Heterozygous female GLX LX, G | LLX = lact. female
Heterozygous male GL ŒE GL = gross.
GG = gross. male
GLX = gross. female
Cross3 | Lact. female LLX LX, L LLX = lact. female
Ra ei male GL G, L Gh = ag male
jm . male
Cross 4 | Heterozygous female) GLX LX, G | LLX = lact. female
‘| Lact. male LL LoL GL = gross. male
More recently Spillman has suggested a simpler ex-
planation that avoids in a sense the postulate of repul-
sion of femaleness and grossulariata. According to
Spillman, if the character for grossulariata be repre-
sented by ‘‘G’’ and femaleness by ‘‘X,’’ then if G (or
L) and X when they meet behave as ordinary allelo-
morphs, the results can be accounted for. The next
table shows how Spillman’s scheme applies to Abraxas.
It is apparent that he has further simplified Castle’s table
by omitting one L whenever it occurs with another G
or L. This arrangement avoids the necessity of the as-
sumption that femaleness is repelled by X (as on the
Bateson-Punnett scheme) because the X that was re-
pelled has become the allelomorph of the G that is pres-
ent and allelomorphs are supposed to move to opposite
poles.
TABLE IIT
ae ents Constitution. Gametes. Offspri a y
Lact. female LX L X GX = gross. female
Gross. male GG G G GL = lact. male
; GX = gross. f
Heterozygous female GX G X = == act. ian”
Heterozygous male GL G L = gross. male
GL a gross. aos
Gx =
ct. female LX L X LX = lact. female
Heterozygous male GL G GL = gross. m
LL = lact. male
Heterozygous female GX G X LX = lact. female
Lact. male LL L L GL = gross. male
488 THE AMERICAN NATURALIST [ Vou. XLIV
It will be observed that in this table the ‘‘ heterozygous
female’’ is GX. She is therefore not heterozygous for
lacticolor unless lacticolor is absence of G.
The case of Abraxas finds a parallel in three charac-
ters in fowls and one in canaries.
The pink eyed cinnamon canary crossed with the black
eyed green canary gives the following results:
P. x B. ¢=100 per cent. Black eyed 3+ 9,
B.? xX P. $= 50 per cent. Black eyed ¢ + 50 per cent.
Pink eyed 2 + 4 per cent. black eyed 9.
Analysis shows (if we reject the 4 per cent. unex-
plained anomaly), that the facts can be explained in the
same way as in Abraxas.
The barred condition of the feathers of Plymouth Rock
fowls is inherited in the same way as the next table shows
when crossed with Langshan.
Ply. ? X Lang. f= 50 per cent. Ply.¢-+ 50 per cent.
Lang. 2,
Lang. ? X Ply. ¢=100 per cent. ¢ and @.
There are two varieties of Game Bantams which ac-
cording to Hagerdoorn give similar results.
Bankiva 2? X Brown red ¢=—50 per cent. Bankiva ¢ +
50 per cent. Brown red 9,
Brown red 2 X Bank. ¢ — 100 per cent. Bankiva ¢ and 9.
Finally yellow shanks and blue shanks in 1 fowls are in-
herited apparently in like fashion.
Yellow 2 X Black ¢— 100 per cent. Yellow ¢ and 9,
Black 2 X Yellow 3 — 50 per cent. Yellow 2? + 50 per
cent. Black g.
These facts are of extraordinary interest, for they
show that certain characters behave in certain ways that
can be explained on the Mendelian formulæ provided
that sex is likewise treated in the same way.
It may seem unfortunate that we have so many pos-
No. 524] CHROMOSOMES AND HEREDITY 489
sible ways of explaining the same facts, and the case
might be turned to ridicule on that score, but the expla-
nations are only variations of the same hypothesis.
Whatever the final decision may be it is interesting and
important to find that the inheritance of sex can be
treated by the same methods used for other alternate
characters and gives consistent results. Let us be as
sceptical as we will, yet the facts will impress them-
selves on any one who takes the pains to think them over.
Such are the experimental results. Looked at not too
eritically they show that by the time that reduction of the
chromosomes occurs, or after that event, there seems to
exist a distinction between the cells, so that half of the
cells are destined to become males and half females.
But, as has been said, unless we assume this process to
take place in one sex only the results can not be ex-
plained. ;
Let us turn then to the evidence which the study of the
germ cells has revealed, which shows that in certain
forms exactly such a process occurs in one sex and not
in the other. I may say at once that the evidence re-
lates to the chromosomes of germ-cells.
Only a few years ago it was generally held that the
number of chromosomes in each species of animals is
constant for all individuals of the species. Every cell
in the body contained the same number.
We now know, however, that in some species of ani-
mals, the female contains one more chromosome than
does the male, and we have a complete account of the
mechanism by means of which this difference arises.
In Anasa tristis and in Protenor, and in a number of
other insects, as shown by Wilson, one chromosome in
the male has no mate. At one division it passes to one
` pole of the spindle, so that one of the two resulting cells
has one more chromosome than the other. This chro- |
mosome is the accessory, or the odd, or the sex chromo-
some, or, as Wilson has called it, the X-element. At the
other division it, like the other chromosomes, divides
into two parts, so that both of the derived cells from this
490 THE AMERICAN NATURALIST [Vou. XLIV
division have the same number of chromosomes. In the
egg the X-element has a pair, another X to all appear-
ances. Thus there are two X’s in the unripe egg, and
one in the sperm-mother cell. These three are appar-
ently identical, and their perturbations I have called the
problem of the three chromosomes. Chance matings
between the two classes of sperm and the eggs (all
alike) give the results shown in the following scheme.
Sperm. Egg. Individual.
X > X XX female.
or
O > X XO male.
The egg that is fertilized by a sperm containing the
accessory produces a female; the egg fertilized by a
sperm without the accessory produces a male.
In a few insects, as in Tenebrio, the X-chromosome
has a smaller chromosome for its mate, as shown by
Stevens. This has been called by Wilson the Y-chro-
mosome. Two classes of sperm are produced with an
equal number of chromosomes, but in one class the X-
element is present, and in the other its smaller mate the
‘Y-chromosome.
All of the eggs of Tenebrio have two X’s, one of
which is lost in the polar body, so that only one remains,
the egg that is fertilized by a sperm bearing the X-
chromosome produces a female, the egg fertilized by the
sperm bearing the Y-chromosome produces a male.
The following scheme shows the results graphically.
Sperm. Egg. Individual.
X X XX female.
or
x X XY male.
In a third class of insects the X-chromosome has a mate
of equal size; consequently all of the sperm, have the same
number of chromosomes of the same sizes. Since we can
not here distinguish X from Y, we may assume either that
_Y is the same as X, in which case we should have the
No. 524] CHROMOSOMES AND HEREDITY 491
problem of the four X’s; or we may assume that despite
their similarity in size they are nevertheless qualitatively
different. In this.case we should still speak of one of
them as Y, and imagine that when a sperm bearing a Y
enters an egg a male results. In favor of the latter inter-
pretation Wilson has pointed out that an unbroken series
of forms exists at one end of which the X-chromosome
has no partner, in the middle of the series a partner of
unequal size, toward the other end of the series a partner
of nearly equal size, and at the end of the series a partner
of equal size. If we are justified in attributing the male
sex to no X, or to Y, it may seem that when Y can no
longer be distinguished by its size it may still be respon-
sible for the production of maleness. On the other hand,
if X and Y do not in themselves produce sex, but simply
accompany more profound changes, they are only indices
of what is taking place and the graded series has no im-
portant significance.
These cases all apply to the group of insects. The
criticism has been made that we are not justified in ex-
tending these conclusions to other groups where no such
difference in number of chromosomes exist.
Quite recently surprising results have been obtained
in groups other than the insects, that go far toward meet-
ing the criticism just referred to.
First Baltzer has found in the sea urchins that there
are specific chromosomes found only in the female. The
spermatozoa are all alike, but the eggs are of two classes.
In principle the outcome is the same except in so far as it
shows that the sex element may be confined either to the
male or to the female. Second, Guyer has found in the
fowl that there is an odd chromosome in the male. This
is the first case reported for the vertebrates, but the
chromosomes in the group are so numerous or the cells
so small that failure to detect two classes of sperm in this
group (if they exist) is not surprising. Lastly, the all-
important outstanding case of Ascaris has been brought
into line by the announcement within the last few weeks
by Boveri of the discovery of an accessory in this group.
492 THE AMERICAN NATURALIST [ Vou. XLIV
In one of the nematode worms of the pheasant he has
found that there are two classes of sperm, one with one
more chromosomes than the other.. Correspondingly,
there are two kinds of embryo, male and female, differ-
ing by one chromosome in every cell.
In the classie case of the nematode of the horse,
Ascaris megalocephala, the reduced number of chro-
mosomes is one in one variety and two in another, it
has been found by one of Boveri’s students that about
half the embryos contain one more chromosome than the
other half. This chromosome is attached to. one of the
others in the early stage and hence does not appear as
single.
This discovery shows that even when no accessory is
found it may still be a part of one of the other chromo-
somes—and being confined to one sex fulfills all the con-
ditions of the sex mechanism.
The conclusions arrived at from a study of these uni-
sexual animals have been confirmed in the partheno-
genetic phylloxerans and aphids.
Two years ago I found that in the phylloxerans two
classes of spermatozoa are present ; one is a rudimentary
sperm, and corresponds to the male-producing of other
insects. The other sperm contains the accessory, and it
alone is functional. Hence all the fertilized eggs should
be female. This has been known for a long time to be
the case.
The female is the stem-mother of the summer brood
of parthenogenetic individuals. They all contain the
full number of chromosomes and are females. At the
time when males appear a peculiar process occurs.
When the male egg gives off its single polar body one
(or two) whole chromosomes lag behind the others (that
divide) and are thrown out into’ the polar body. Hence
this egg contains two less chromosomes and it develops
into the male. In the sexual female no such reduction
takes place.
Here then we faa a mechanism in the pale to produce
only females, but also another mechanism in the par-
No. 524] CHROMOSOMES AND HEREDITY 493
thenogenetic female for producing males. The facts
make out a strong case in favor of the view that we have
probably found the mechanism by means of which sex
is determined.
When we try to analyze the results, however, I mean
when we try to make clear to ourselves how the acces-
sory determines sex, we fail to make good a consistent
story of the process.
If we assume, as Wilson and I have done, that the re-
sult is purely quantitative in that the female develops
because the egg fertilized by the female producing sperm
contains one more chromosome than the egg that be-
comes a male; when we make this assumption, we seem
to leave unexplained how sex is determined in a large
number of cases when the odd chromosome has a
partner of equal size.
On the other hand, if we assume that the accessory
is a qualitative agent producing females in this way;
then the mate of the accessory, or one of the correspond-
ing chromosomes in the female, must be male-producing.
To make this mechanism ‘‘go’’ we must assume select-
ive fertilization; for which at present there is no evi-
dence.
I shall try to indicate in the barest outline the further
analysis of the two statements just made.
When the accessory has no mate, as in the examples
just given, we have the problem of the three X-chro-
mosomes. The following situation then develops.
(A) The three X’s are identical as everything we
know about them indicates. Their position on the reduc-
tion spindle both in the male and female is so far as we
know fortuitous. It follows then the female results when
two X’s meet in the same egg, and a male when only one
X is present. This is the simplest explanation yet found
that is strictly in conformity with observed relations for —
this class. It encounters five difficulties: first, it does
not seem to apply when the accessory has a mate of
equal size, if that mate be another X (see below);
second, sex in hermaphroditic forms is not apparent
494 THE AMERICAN NATURALIST [ Vou. XLIV
on this view; third, the mate of the accessory when it
exists, if it is not an X but a Y element, isignored; fourth,
in Acholla the Y element is larger than the combined X
elements all taken together; fifth, it may seem to reduce
the male to a less highly developed form than the female
in the sense that it lacks a quantitative factor and leaves
unexplained the characters peculiar to the male.
(B) If the three X’s are not identical, but consist of
two female and one male element, and if they are undi-
rected on the spindle, the results can be explained only
by assuming selective fertilization. The assumption
meets with a flat contradiction in that it must assume
that the only X in the male is a female X. Were it as-
sumed to be a male X, the scheme will not work out.
Moreover, there is no evidence for selective fertilization.
(C) If the three X’s are not identical, but male and
female, and are directed on the maturation spindles,
equality of males and females will result only on the as-
sumption of selective fertilization. Three assumptions,
all unknown, are necessary to work out this scheme.
Let us turn our attention to the class with three X’s
and one Y. I take the simplest case for analysis in
which all three X’s are assumed to be alike. The sperm,
bearing the X, fertilizing any egg (for all eggs have an
X), produces a female, the sperm bearing the Y fertiliz-
ing any egg produces a male. We know this, in fact, to
happen whenever we can identify Y. This scheme meets
with no difficulties on its own account, and appeals (with
certain modifications) more directly to my mind than
any other; but it meets with a difficulty when no Y is
present; and also when Y is the same size as X, if this
size relation identifies Y with X. Unless these points
can be met the hypothesis is insufficient to meet the situa-
tion. I shall return to these difficulties in a moment and
try to meet them. This is the extreme application of the
particulate theory, and has the advantages and disad-
-= vantages of its kind.
On the other hand, there is no need to assume that X
is the sex chromosome in the sense of carrying sex. The
No. 524] CHROMOSOMES AND HEREDITY 495
use of this term, I fear, prejudices the situation by the
very aptness of the application. It may be that X only
means more X, and that this is a factor in sex determina-
tion. The only criticism that I have to offer of this view
is that it ignores the Y element, and thereby makes the
male condition the result of the absence of something
which, if present, turns the embryo into a female. It
seems to me that there is no warrant for considering the
male in this sense a lacking female. The physiology and
the biology of the males offer much to contradict such a
view of his composition. I should also object to the
above conclusion on the general grounds that it refers
a particular character to a single chromosome.
Can we meet these objections if we admit that when
the Y chromosome is absent the things that it stands for
are redistributed, or are present in the other chromo-
somes whether equally or unequally distributed there
need not be decided? Correspondingly, the materials of
the X chromosome may be supposed to be distributed
in part also to the other chromosomes. The production
of male or female will then be determined by the prepon-
derance of the amount of X or of Y in any given combi-
nation.
The groups with an accessory represent from this
point of view an extreme form of distribution of the X
material; while those with a Y show a like distribution
of the Y material, but in neither case need we imagine
all of this material present in a given chromosome, îi. e.,
in X or in Y. But this assumption also meets with
difficulties in another direction, for we should be obliged
to assume that the chromosomes carrying the Y element
pass to the opposite pole at one division from those bear-
ing the X element and we have as yet no evidence to sup-
port such a view. .
These are some of the difficulties of interpretation: |
Science advances by carefully weighing all of the evi-
dence at her command. When a decision is not war-
ranted by the facts, experience teaches that it is wise to
suspend judgment, until the evidence can be put to fur-
496 THE AMERICAN NATURALIST [ Von. XLIV
ther test. This is the position we are in to-day concern-
ing the interpretation of the mechanism that we have
found by means of which sex is determined. I could, by
ignoring the difficulties and by emphasizing the impor-
tant discoveries that have been made, have implied that
the problem of sex determination has been solved. I
have tried rather to weigh the evidence, as it stands, in
the spirit of the judge rather than in that of the advo-
cate. One point at least I hope to have made evident,
that we have discovered in the microscopic study of the
germ cells a mechanism that is connected in some way
with sex determination; and I have tried to show, also,
that this mechanism accords precisely with that the ex-
perimental results seem to call for. The old view that
sex is determined by external conditions is entirely dis-
proven, and we have discovered an internal mechanism
by means of which the equality of the sexes where equal-
ity exists is attained. We see how the results are auto-
matically reached even if we can not entirely understand
the details of the process. These discoveries mark a dis-
tinct advance in our study of this difficult problem.
SPIEGLER’S “WHITE MELANIN” AS RELATED
TO DOMINANT OR RECESSIVE WHITE!
DR. ROSS AIKEN GORTNER
STATION FOR EXPERIMENTAL EVOLUTION, Coup Sprina Harsor, N. Y.
INTRODUCTION
THe study of melanin has interested a great number
of chemists during the last century and of especial in-
terest was the announcement by Spiegler,? in 1904, that
he had succeeded in obtaining a ‘‘white melanin’’ from
sheep’s wool and white horse hair.
The question of white plumage and hair color has
been widely studied from breeding standpoints—at-
tracting unusual interest from the fact that there are
undoubtedly two varieties of white, one of which is
dominant and the other recessive. The reason for this
peculiarity seemed, therefore, to be explained by the
discovery of the ‘‘white melanin.’’ In the light of this
new knowledge it would seem that one variety of white
was produced by the presence of a white coloring matter
and that this would be dominant in a cross with another
color having a weaker determiner. The recessive white,
however, would be recessive because there would be an
entire absence of pigment and would therefore be a case
of dominance of color over absence of color.
-© Riddle, in referring to Spiegler’s work, seems to take
this view, as does also Spillman.* Spiegler,> in a later
paper, while giving no further experimental work on
1Used in the Mendelian sense. [Contribution from the Biochemical
Laboratory of the Station for Experimental Evolution, The Carnegie Insti-
tution of Washington. ]
2 Spiegler, Hofmeister’s Beitr. z. Chem. Physiol. u. Path., 4, 40, 1904.
3 Riddle, Biol. Bull., 16, 328, 1909.
. 4 Spillman, this journal, 44, 119, 1910.
5 Spiegler, Hofmeister’s Beitr. z. Chem. Physiol. u. Path., 10, 253, 1907.
497
498 THE AMERICAN NATURALIST [Vowu. XLIV
‘‘white melanin’’ seems also to suggest that the two
whites are due to the presence and absence of melanin.
He states:
It is readily understandable that white horse hair can not be without
pigment. We know pigmentless hair, i. e., albinos, these have appar-
ently the natural color of the keratin (Hornrohstoffs) from which the
hair is formed, modified by a special morphological condition. These
questions need a more searching study. We must now determine
whether albino hair gives the same oxidation products as pigmented
hair. It is in this manner that we can finally decide whether the color
of gray hair is due, as we have previously supposed, to disappearance
of pigment and air content or rather to the change of the darker pig-
ments into lighter ones.
It is in this condition that the study was left. Inasmuch
as this question is of the utmost importance from the
standpoint of heredity, the work of melanin investiga-
tion has been taken up in this laboratory.
In a study of Spiegler’s® paper the most noteworthy
detail which appears to be wanting is a comparison be-
tween the percentage of black pigment in the black wool
or hair and the percentage of ‘‘white melanin’’ found in
the white varieties. Spiegler gives the method of isolation
as practically the same for both varieties, but does not
mention the yields of melanin obtained. He, then, gives
his analytical data leading to an empiric formula of
CoH;,N,SO,. calculated to ash-free (ash — 9.8 per cent.)
melanin from black horse hair and C,,H,.N,,SO., calcu-
lated to ash-free (ash — 16.28 per cent.) ‘‘white mela-
nin’’ from white horse hair.” He further states:
The black pigment body with the simplest formula of C,,H,,N,SO,.
and the light pigment body of C,,H,,N,,SO,, differ, as the analytical
data show only a little (“ein Geringes’’) and it is very apparent that
they are identical in nucleus (“im Kerne ”), and that the different color
is due to the entrance of a chromatic group. Very apparent is the
great difference in hydrogen content. The whlte pigment contains
much more hydrogen, oxygen and even nitrogen, while the carbon-poor
one is the black. The light pigment body is at the same time the
oxidation and reduction product of the darker one.
è Loe. cit.
"His formula for melanin from black and white wool are respectively
— CyH..N.SO.. (ash==10.85 per cent.) and C,,H NSO. (ash==2.30 per cent.).
No. 524] SPIEGLER’S “WHITE MELANIN” 499
In other places, however, he prefers to call the white
body an oxidized black pigment. In his paper no
comparison is made of the black and white wool prod-
ucts; here we have formule assigned by Spiegler as
CygHosN,SO., and Cy,H,,N,.SOs., respectively. In this
case white could not be an oxidized black, neither does
the lower carbon percentage belong to the black. It is
incomprehensible to the author why Spiegler should
assert that ‘‘it is apparent that both are identical in
nucleus.” The only point of identity which is apparent
is that the same elements enter into the composition of
each, but the proportions are so widely different that no
close relationship seems possible. Coupling this with
the facts that from black wool, treated in a manner very
closely resembling Spiegler’s method, the author has ob-
tained 1.84 per cent. of black melanin, while from white
wool only 0.06 per cent. of a grayish-brown’ body was
obtained by an exactly similar method; and also that
albino hair (from white rabbits), obtained through the
courtesy of Dr. Castle of Harvard College, gave 0.03 per
cent. of a grayish-brown body; feathers from a recessive
(albino) fowl (silky) gave 0.155 per cent. of a similar
body and feathers from a dominant white fowl (white
Leghorn) gave 0.195 per cent., it appears that Spiegler’s
‘‘white melanin’’ is not a substance belonging to the mel-
anin class, but is a product produced from the keratin by
the action of alkalies. The author has been able to find
no data as to the actual percentage of keratin in the hair
or feathers of the various animals, but it seems probable
that the coarser the covering of the animal, the greater
the percentage of keratin. Thus in the fowls we find
the coarse ribs of the feathers, which are composed
almost wholly of keratin, while in the white rabbit the
hair is very fine and silky and contains, supposedly, less
keratin than the intermediate wool of sheep, which is
more similar to the rabbit hair. The same holds true of
the decomposition product found if we assume it is due
*Spiegler describes his ‘‘pigment’’ as ‘‘a light gray brown powder.’’
500 THE AMERICAN NATURALIST [Vou. XLIV
to the keratin—the coarser the structure of the coat the
larger was the percentage of the decomposition product.
Even if this view is not correct we know that the various
keratins do not have the same composition, and, there-
fore, we should look for a variation in any one decom-
position product.
METHOD or ISOLATION
A weight of wool was boiled with a 10-per-cent. solu-
tion of sodium hydrate! in the proportion of 300 grams
to 1 liter for four hours. The solution was then poured
into water, strongly acidified with hydrochloric acid*
and the precipitate allowed to settle. The supernatant
liquid was syphoned off and the precipitate washed by
decantation. The precipitate was then stirred with
from 5 to 10 liters of 0.2-per-cent. sodium hydrate solu-
tion and filtered. The filtrate was precipitated by
hydrochloric acid and allowed to settle, the liquid
syphoned off and the precipitate dissolved in one liter
0.2-per-cent. sodium hydrate solution and again filtered,
precipitated with hydrochloric acid, washed free of
chlorides, dried at 100° and, lastly, extracted with car-
bon disulphide, alcohol and ether in Soxhlet apparatus,
then dried at 105° and weighed.
Discussion
From the table given below it can be seen that ‘‘ white
melanin’’ does not exist in either recessive or dominant
whites, but that there is some product formed by the de-
composition of the keratin, which behaves like a melanin,
i. e., is soluble in alkali and insoluble in acids or neutral
solvents; perhaps this may be shown to belong to the
melanin class, but it is at least common to all white
plumage and hair.
°’ See Hoppe-Seiler’s ‘‘ Handbuch ar pei und Pathologisch
Chemischen Analyse,’’ Berlin, 1909, pp. 519.
* An exhaustive research as to the ober of various strengths of sodium
hydrate solution upon melanin is in progress in this laboratory, the details
of which will soon be ready for publication.
“A copious evolution of hydrogen sulphide was observed in each case-
No. 524] SPIEGLER’S “WHITE MELANIN” 501
The results obtained are given in the following table.
Substance. Weight. | Vol. alkali. — “ Pigment” found. | ask
1. Black wool!? 400 gr. | 1340 c.c. 10% 7.35 gr. 1.84
2. White wool” S 500 1675 10 0.30 0.06
3. 500 1675 10 0.30 0.06
4. rabbit a 100 350 10 0.03 0.03
5. Silky feathers! 2 110 350 10 0.17 0.155
6. 105 700 5 0.24 0.22
yg ay 95 3000 1 0.16 0.168
8. White leghorn 46 200 10 0.09 0.195
feathers!
9. Cow’s horn (color- 40 200 10 Lost before
less) eighing, but
present inap
iable
amount.
If the theory of v. Furth’ is correct that melanin
formation is the product of an oxydase acting upon an
oxidizable. chromogen, it would appear very probable
that dominant whiteness is due to the presence of an
inhibitory enzymet in the epithelial cells which pre-
vents the action of the oxydase, and that recessive whites
differ by having neither the power to produce pigments,
îi. e., lack of oxydase or chromogen, or both, nor do they
possess the anti-oxydase which distinguishes the domi-
nant whites. This being the case, the one type would
be always dominant, its determiner being the anti-
enzyme, and the other type (i. e., albinos) would of neces-
sity be recessive, inasmuch as, while they lack the power
to produce pigment, they also are without means of in-
hibiting pigment production when the elements for its
12 Recessive in the Mendelian sense.
13 Dominant in the Mendelian
% Had been previously doused " 40° for 48 nl with 9 liters of
0.2-per-cent. hydrochloric acid containing 18 grams of pepsin (Merck’s
**scales’’ 1 3 3,000).
15y, Furth u. Schneider Hofmeister’s Beitr. z. Chem. Physiol. u. Path.,
1, 229, 1902. v. Furth u. Jerusalem, ibid., 10, 131, 1907.
18 For the literature of the anti-enzymes see Vernon, ‘‘Intracellular
Enzymes,’’ London, 1908, pp. 208-211, and Kastle, ‘‘ The Oxidases,’’ Bull.
No. 59, Hyg. Lab., U. S. Pub. Health and Mar.-Hosp. Serv., Wash., pp. 66
and 87, 1910.
502 THE AMERICAN NATURALIST [Vou. XLIV
formation are present. Davenport!’ has already put
forward a view very similar to the above and it is hoped
that in the near future this laboratory will have sufficient
data to test this hypothesis.
SuMMARY
1. Dominant and recessive whites in the Mendelian
sense, have no relation to the presence of Speigler’s
‘‘white melanin.’’
2. The ‘‘white melanin’’ was found to be present in
all forms of keratin structure which were studied, but
in very small amounts as compared with true melanin
from black wool.
3. In view of the small percentage of ‘‘white melanin’’
found, Spiegler’s view that it is an ‘‘oxidized black’’
seems impossible; neither is this view upheld by a study
of Spiegler’s work.
4. It seems highly probable that Spiegler’s ‘‘white
melanin’’ bears no relation to true melanins, but is a de-
composition product of the keratin.
5. A theory is advanced that dominant whites are due
to the presence of an anti-oxydase which prevents pig-
ment formation; recessive whites, on the other hand,
have neither power to form pigments nor to inhibit the
formation.
** Davenport, Report Am. Breeders’ Assoc., 5, 382, 1909.
SHORTER ARTICLES AND CORRESPONDENCE
A PICKWICKIAN CONTRIBUTION TO OUR KNOWL-
EDGE OF WASPS.
To THE EDITOR OF THE AMERICAN NATURALIST: It is very idle
to criticize the critic, especially when he happens to be a per-
sonal friend! Still, I think the frequency of wasps’ nests in
Buckinghamshire is not part of the wide knowledge possessed by
Dr. Raymond Pearl, or he would hardly suggest that queen
wasps collected over nearly six square miles in the cottages of a
Buckinghamshire rural district in the spring could by any con-
ceivable probability be members of a single nest dispersed in the
preceding autumn. Last year in the autumn I had taken for
me upwards of fifty nests on the land of one small farm in the
same county. Indeed, in the collection which Dr. Pearl con-
siders might come from one nest, there were two or three races
present, besides Vespa vulgaris, when the material was sorted
out, conclusively demonstrating that if we obtained samples of
relatively rare species we must be drawing from a very large
number of nests. In fact, my guide in this matter—an ento-
mologist with a very extensive knowledge of English wasps—
writes of this collection, ‘‘I should not hesitate to regard them
as a random lot.’’
Other nests are in hand, as well as population collections, but
the main point brought out in the last paper, as in Dr. Warren’s
termite paper, is the fact that the variability of a population is
almost double the variability within a single nest. Dr. Pearl as
a ‘‘pure-linist’’ would find wasps an interesting study, although
I fear that if he attempted to breed with the needful 100 to 200
nests, he might experience difficulties—and not only from the
wasps! When he does so, I have little doubt that his experience
and knowledge will enable him to replace by more solid data the |
‘‘Pickwickian’’ contributions of the much-abused biometricians.
RL PEARSON.
BIOMETRIC LABORATORY,
UNIVERSITY COLLEGE
London, England,
May 20, 1910.
503
NOTES AND LITERATURE |
HEREDITY
Tue Fifth Report of the Evolution Committee of the Royal
Society (London), like the preceding reports of this committee,
is full of exceedingly interesting results of experimental work.
Professor Bateson’s committee is doing much to unravel the
tangled thread of Mendelian inheritance. In the report in ques-
tion I. B. J. Sollas gives the results of studies of color inheritance
and of the inheritance of supernumerary mamme in guinea pigs.
The color factors recognized are:
G= factor for agouti ticking of the cag
B= factor for black pigment in eye and s
R= factor for red pigment in hair and EA "es chocolate pigment in eye
and skin.
Ch = factor yi nee pigment in hair, skin and eye.
C= factor for ¢
Albinos with which he worked had colored points, hence in
them the factor C was not absent, but either merely deficient or
controlled in such a way as to confine color to the extremities.
The colored forms fall into two series—one black-eyed, the
other ruby-eyed. In the series of black eyes we have the three
color types agouti (GBRChC), black (BRChC) and red (BRC).
In the ruby-eyed series we have cinnamon (GRChC), chocolate
(RChC) and red (RC). The author is not entirely clear in
the explanation of some of his formule. For instance, he offers
no explanation why B does not occur in the hair of the red type
in the black-eyed series. He does state, however, that in agoutis
red spots occur because B fails to develop. Red spots occur also
on black individuals for the same reason and on cinnamon indi-
viduals because of the failure of the chocolate pigment to de-
velop. Each of the colors has one or more dilute forms.
The method of inheritance of supernumerary mamme was not
clearly made out. Several dwarf individuals occurred. Only
- one of these lived to maturity.
Miss Wheldale, in the same volume, gives further observations
upon the inheritance of flower color in Antirrhinum majus. A
chromogen (Y) allied to the flavone series of coloring matters
appears to be the basis of color in these flowers. From this a
504
No. 524] NOTES AND LITERATURE 505
yellow (xantheic) pigment arises which, when unmodified by
ferments, gives rise to flowers with yellow lips, though the throat
is ivory white. In some strains this yellow chromogen appears
to be modified by a ferment (I) in such manner as to give flowers
having both lips and throat ivory white (except for certain
patches of yellow in the palate). An oxidase (L) acting on
Y as modified by I gives a tinging of magenta color in the lips.
L acting on Y in the absence of I gives crimson. A factor T,
when present, causes the magenta color to extend from the lips
into the tube. A factor D, probably also a ferment, deepens the
shade of magenta, giving the color of the wild plant. D acts
only in the presence of Y or I and L and T. Still another
factor further intensifies the shade of color. Striping also
occurs, the factor for striping being allelomorphie to D and re-
cessive to it. There is also a concentration factor S. When
S is homozygous the stripes are of an ivory background; when
heterozygous the stripes are of a pale-colored background.
Chemical studies indicate each of the color factors to be due to
different definite compounds. - An albino variety arises in the
absence of Y. The albino is distinguishable from the ivory white.
Miss Marryatt, in the same volume, gives the results of the
study of color inheritance in Mirabilis Jalapa. She finds a fae-
tor C for colored sap and a factor M which turns yellow sap red.
One white strain was found to be lacking in both C and M. An-
other white strain had M but not C. The latter crossed with
yellow gave red. The formula of the yellow strain was CCmm.
The formula of the crimson strain was CCMM. Yellows hetero-
zygote for C were paler in color than the corresponding homo-
zygotes. Heterozygotes of the composition CeMM were magenta;
those of the CCMm an orange-red, and CeMm magenta rose. ;
The behavior of ‘‘flaking,’’ a form of striping, was not fully
made out.
Miss Wheldale also gives some very interesting results in an-
other part of the report on the physiological interpretation of
Mendelian factors for color in plants. White varieties of sweet
peas and stocks were found to contain a colorless flavone (chro-
mogen). Colored varieties are assumed to possess this chro-
mogen in various stages of oxidation. Each shade of color ap-
pears, from chemical tests, to represent a distinct substance.
Chemical studies of white and colored strains point to the follow-
ing system of factors as the cause of color production: P is a
peroxidase which sets oxygen free from X; X is a substance -
which functions as a peroxide; A is a ferment or oxidizer which
506 THE AMERICAN NATURALIST [Vou. XLIV
reoxidizes X with atmospheric oxygen; C is a chromogen, the
oxidation of which, by the combined action of A, X and P,
gives anthocyanin. Additional factors, A,, X, and P,, similar
in a general way to A, X and P, convert red into bluish-red and
purple. Chemical tests indicate a shortage and not always
entire absence of some of the above factors in white varieties.
This bit of information is important in connection with the tele-
one theory recently proposed by the writer in an article in the
AMERICAN NATURALIST, and accords with that theory.
Baur has recently published an extremely interesting report
on his study of inheritance in Antirrhinum. He gives some
interesting details of methods with special reference to the
avoidance of error in experimental work of this kind. He has
found 22 unit characters, but deals with only 13 in this paper.
Baur recognizes the following colors in Antirrhinum:
White = Miss Wheldale’s white.
Yellow = Miss Wheldale’s yellow.
enbein = Miss Weldale’s ivo This differs from white by the
presence of a ce chromogen, seceding to Miss Wheldale.
Rose-back; flesh-colored; chamois-rose; red; pale red; dark red; rubin.
The last six are superposed on yellow or ivory, and each of them
may appear whole or as delilahs—that is, on lips only. The
colors chamois-rose, red, dark red and rubin may also be striped
(picturatum).
papal recognizes the following color factors:
B (= Miss Wheldale’s Y) is the basis of color.
bb is pure white, distinguished from ivory by absence of yellow in the
throat.
B unmodified by other factors is yellow.
C in the absence of F (see below) converts B into elfenbein (ivory),
and IPLE Wheldale’s J.
e absence of R (see below) and in the presence of B causes a
light r rose apne on the back of the flower, with a spot of similar shade on
each side of the stem near the spur, giving Baur’s rose-back type.
R with B and F gives flesh-color; but without B and F, R gives no effect.
M in the absence of A and the presence of ra ef and R gives chamois-rose.
A in the presence of B, F, R and M gives
n the presence of B, F, R, M and A, a ion red. z the series
of kaai BFRMAL, each factor is dependent on all befor
D spreads color from the lips over the tube. When D is pa all col-
ored flowers have ivory or white tubes. D also makes the color of the lips
ap prominent. The factor D is independent of all previously mentioned
G gives striping on colored ground.
pag Baur, ‘‘Vererbungs- und Bastardierungs-Versuche mit antirrhinum,’’
Zeitsch. $ Ind. Abst.- u, Vererb., 1910, Bd. IIT, H. 1 u. 2, pp. 34-98.
No. 524] NOTES AND LITERATURE 507
O gives red veins on ground containing no red. This factor shows in
the presence of B, R, F and C, and may belong in the series BFRMAL
between R and M. This point is not yet determined.
vith B, F, R and M gives a peculiar shining rose color. It probably
belongs in the above series after M, but may be identical with L
Another factor gives a faded appearance to the edge of the
lower lip of red flowers. There also appears to be a factor
that governs the width of the yellow spot on the lower lip of red
flowers. Investigation of four other factors which appear to
affect flower color is in progress.
The author thinks there are possibly 20 factors concerned in
flower color in Antirrhinum majus. Several factors not yet
fully investigated influence the size of the flower, the relative
size of the two lips, ete.
In addition to factors affecting flower color the following were
made out:
E. When this factor is missing the flowers are radial (peloric).
P. The absence of P gives a peloric form different from that caused by E.
Another factor when absent gives a split corolla different from
the normal zygomorphic form.
An apetalous flower is also known, but its inheritance is not
worked out.
-All of the flower color factors, except perhaps the one for
striping, affect leaf color. There are also other factors which
affect the intensity of red in the leaves. Two affect the green
color. The absence of one of them produced the chlorina type
previously mentioned in these notes. The absence of the other
produced the aureas, also previously mentioned, and which are
intensely yellow-leaved, being unable to grow.
The number of factors which affect leaf form are, for the
most part at least, identical with those affecting the flower form,
but are not yet fully investigated. The factors affecting the
habit of growth are not yet fully worked out. Some of them
seem to be identical with some of the flower-color factors. One
character has been found that certainly does not Mendelize.
This is a variegation conditioned by the cytoplasm. Only three
of the factors studied are completely dominant; the others are
incompletely so.
aur, in another paper,’ presents some very interesting a
dence in favor of the hypothesis that the so-called graft hybrids
are periclinal chimeras, the surface tissue being that of one
parent form, the underlying tissue that of the other parent.
Examples of such hybrids are Cytisus Adami, Crataegus-
2 Ber. d. Deut. Bot. Gesellsch., Bd. XXVII, H. 10. _ Cire
508 THE AMERICAN NATURALIST [Vou. XLIV
Mespilus graft hybrid, and H. Winkler’s tomato-nightshade
graft hybrid. The suggestion that the vegetative point of such
forms consists of a more or less irregular mixture of the two
tissues could hardly be true because one or the other tissue would
soon gain the ascendency. Baur suggests that a careful study
of mitosis in the vegetative point of such forms might settle the
question.
East has recently published an interesting paper? dealing
With the effect of selection on fluctuations. The conclusion is
reached that neither the relative content of dry matter nor that
of the nitrogenous matters of the potato can be changed by the
selection of fluctuations and their subsequent asexual reproduc-
tion. In most potato fields there will occasionally be found
plants which remain green after the main crop has matured and
the vines died. East made a selection of plants maturing early
and those maturing late, in some cases finding lateness or earli-
ness reproduced in the selection, in others not. In one of these
cases the long-lived plants selected from a variety were found to
have pink sprouts, while a short-lived plant from the same
variety had white sprouts. East suggests that either bud varia-
tion had taken place or that there had been an accidental mixing
of two varieties.
There has been a good deal of work on selection for yield and
other characteristics in old agricultural varieties, which indicate
that bud variations or permanent mutations of one kind or an-
other occasionally take place in such varieties, and that they
gradually break up into a mixture of biotypes, which may differ
in a considerable number of characteristics, including yielding
power. Selection within such a variety might then result in
the isolation of strains of better quality than the general average
of the variety.
It seems to the writer that Dr. East has hardly given sufficient
attention to the possibility of selection for improvement in old
strains in which a considerable number of important mutations
may have occurred. For instance, he says:
As a result of these experiments I will not go so far as to say that
variations in power of resisting physiological or fungus diseases do not
occur in asexual reproduction, but I do believe that the relative proba-
bility that the commercial grower will obtain disease-resisting varieties
by this means is negligible.
So far as newly isolated pure strains are concerned, the writer
Che M. East, ‘‘The Transmission of Variations in the Potato in Asexual
= plate 1. 7 Connecticut Experiment Station Report, 1909-10, pp. 119-
P
No. 524] NOTES AND LITERATURE 509
agrees very fully with this statement. There has, however, been
a good deal of work which indicates that in old agricultural
varieties variations have frequently occurred which render selec-
tion with a view to isolating the best strains present justifiable.
Thus Waid, of the Ohio Experiment Station, Zavitz, of the
Ontario Station, and L. G. Dodge, of the U. S. Department of
Agriculture, have, by selection in old varieties of potatoes, ob-
tained strains which outyielded the variety from which the selec-
tion was made. It is true the objection may here be urged that
the supposed variety from which the selection was made was
really a mixture, but this point is granted. The only question
is as to how the mixture came about, whether by mutation or
by mechanical mixture. It may not be possible to settle this
question definitely because of the difficulty of proving the purity
of an old variety; but the results that have been accomplished,
it appears to the writer, do justify selection in old varieties with
a view to isolating superior strains. After all, Dr. East would
probably agree perfectly with the writer in what has just been
said.
Concerning the character of bud variations, a number of which
were found in East’s work, the author gives it as his opinion
‘that practically all, if not quite all, bud variations are losses
of a dominant, or epistatic, character allowing the appearance
of a recessive, or hypostatic, character.” He mentions four pink
or red varieties that produced white variations that were
constant the next season; also a purple variety produced a
similar white variation. Several apparent changes from white
to colored tubers appear, but they were not hereditary, and the
varieties producing such variations had pink sprouts. Two
varieties are mentioned in which changes of shape from long
to round tubers occurred, the changes being permanent. Sev-
eral other similar changes occurred but were not permanent.
Change from shallow to deep eyes occurred in four varieties. In
one case a peculiar change in the habit of growth of the tuber
occurred, the peculiarity consisting in the formation of two
tubers on the same rootstock at some distance from each other.
This occurred in several varieties, but in only one case was it
hereditary. It is not known whether the new type is recessive
or dominant, but in the bud variations above discussed the new
types are all recessive. The author suggests that these bud
variations ‘‘seem to show that Mendelian segregation is ne
limited to the reduction division in the maturation sexual ce
It does not seem to the writer that this is a necessary apo
510 THE AMERICAN NATURALIST [Vow. XLIV
Bud variations would certainly arise if Mendelian segregation
occurred in somatie division, but they would also occur if for
any reason a dominant character should become latent. It cer-
tainly yet remains to be demonstrated that they arise from
Mendelian segregation in somatic tissues.
Kastle has recently published a very important paper in ee
he summarizes the results of investigations relating to oxidases
and related compounds. The paper is too extensive to permit
of an adequate review at the present time. It has, however,
a very important bearing on many Mendelian phenomena, and
those who are interested in this subject will enjoy reading this
excellent bulletin.
uyer has recently given us a very thoughtful paper® on the
possible relation of the chromosomes to hereditary characters.
His argument is directed specifically against the Weismannian
hypothesis of determinants. He does not attempt to minimize
the importance of the nucleus in ontogeny or in heredity, but he
is inclined to regard the development of what we call hereditary
characters as a result of interrelations between the nucleus and
the cytoplasm.
Speaking of experiments in which fragments of protozoa con-
taining various proportions of the nucleus regenerated the or-
ganism, he says:
If the nucleus is an aggregate of qualitatively different morphological
units, one would expect parts to be missing in the regenerative protozoa
in proportion to the amount of nuclear matter removed, but the evi-
dence does not bear this out. The regeneration is seemingly complete,
only a longer time is Teee if but a small fragment of the nucleus is
left in the piece.
These experiments on protozoa disprove the determinant
theory as held by Weismann, de Vries and others..
Guyer points out that the bulk of the fertilized egg is cyto-
plasm of maternal origin and that the developing organism must
therefore be more of maternal than paternal origin.
Nevertheless, we can see how the veneer of individual traits may be
equally of maternal and paternal origin if, to express it crudely, we
look upon cytoplasm and chromatin, respectively, as responsive mech-
anism and inciting agent, the character of the response depending
both upon the constitution of the cytoplasm and the materials (enzymes?
nutritive substances?) emanating from the nucleus.
+J. K. Kastle, ‘‘The Oxidases,’’ Hygienie Laboratory Bul. No. 59,
December, 1909.
5M. F. Guyer, ‘‘ Deficiencies of the Chromosome Theory of Heredity,’’
: University í of Cincinnati, Series 2, Vol. V, No. 3, September—October, 1909.
ve ee
No. 524] NOTES AND LITERATURE 511
For many years the writer ‘has held the view that in so far as
the chromosomes have a relation to hereditary characters the
influence they exert results from the relation they hold to the
nutritive processes. He is therefore prepared to accept Guyer’s
views as expressed above.
Guyer gives a very striking analogy for the possible part which
cytoplasm and chromatin may play in the development of specific
characters.
Any one of several species of insects may produce galls on a given
plant, but each kind of insect always produces its own specific type of
all. Here is an actual case of living protoplasm producing a specific
character through the activity of its specifie exciting agent—that is,
the reaction between certain secretions of the insect and the living sub-
stance of the plant produces new and definite structures.
Change either factor and the resulting structure must be
modified.
Likewise in the germ cell, alterations in the constitution of either
chromosome or cytoplasm must undoubtedly produce structural changes
in the adult.
He further points out that the chromosomes may be looked
upon as the greater source of variability because they are derived
in much greater proportion from the two parents than is the
eytoplasm.
Guyer intimates that changes first initiated in the chromatin
might be reflected on to the cytoplasm from time to time and
there conserved. While it would seem to be possible that changes
in the chemical constitution of a chromatin body might effect
changes in other chromatin bodies and in the cytoplasm, I see no
reason why such an assumption is necessary to account for
permanent and fundamental evolutionary changes. I think we
may look upon the cytoplasm and each of the chromosomes as
having more or less of an individual existence and that each of
them may undergo evolutionary changes in constitution more or
less independently of the others, though, as above pointed out,
a change in one of these cell organs might initiate changes in
others. We may look upon the organism at any time as merely
an expression of the, complex relations then existing between
the cytoplasm and the chromosomes and between the various —
chromosomes themselves. These relations are disturbed by any
fundamental change in the composition or metabolic activities of
any of these cell organs. For instance, the dropping out of a
chromosome might not only change quantitative relations be-
tween various metabolic activities, but it seems possible that at
least some of the chromosomes may possess characteristics which
a
512 THE AMERICAN NATURALIST [Vou. XLIV
would give rise to qualitative changes, in case the chromosome
should drop out. I have pointed out elsewhere® that in order
to explain Mendelian phenomena on the basis of the behavior of
chromosomes in the reduction division, it is not necessary to
assume in the chromosome definite pangenes or determinants as
separate entities. Each chromosome may take part in all phases
of development. It is hardly probable that any particular chro-
mosome, with the possible exception of a few of them, possesses
exclusively characteristics necessary to the continued existence
of the race in which they occur. In other words, speaking in a
general way, each of the chromosomes may possess all the meta-
bolic powers necessary to the race, while at the same time each
chromosome may differ from others in minor particulars, giving
rise to such differences as we see in Mendelian character pairs.
The writer does not quite follow Guyer in doubting the ade-
quacy of the above interpretation of Mendelian phenomena, be-
cause in a few instances inheritance of a different type has ap-
parently been found, but he does agree with him when he says:
There are no sufficient reasons, I think, why we may not look upon
their (the chromosomes’) differences as differences of mere elemental,
chemical and physical constitution rather than as differences among
systems of determinate morphological units. .. . Hea in case of the
divorcement of particular parental chromosomes in gamete . it
would seem that we might account for the so-called "Mendelian ie:
nomena by attributing to. the chromosomes simply chemical and phys-
ical differences without endowing them with morphological entities.
Guyer points out that because the three elements carbon,
oxygen and hydrogen condition substances of which they are
components, we do not postulate a specifically determinative
substance in any of them for each of the numerous carbohy-
drates and other products that result from their various com-
binations and arrangements. Similarly, we do not need to infer
definite structural elements in the chromosomes, each of which
is specifically determinative of a given character. It would seem
more logical to assume that the differences between related organ-
isms may be due to differences in the combinations of metabolic
activities found in the various cell organs.
This paper of Guyer’s accords very closely with the teleone
theory of heredity propounded by the writer in the April num-
ber of the AmERICAN NaturRAist, 1910. It is gratifying to see
that a number of biologists are coming to the view that the
main facts of heredity can be explained without the assumption
4 hypothetical units in the germ plasm. W., J. SPILLMAN.
serial NATURALIST, April, 1910.
Methods in Plant tustoigy
By CHARLES J.
CHAMBERL
Second edition, revised and much enlarged ; 272 pages, with 88 aiea 8vo, cioth ; net $2.25,
postpa
aid $2.39
"IGE first complete manual to be published on the subject of botanical micro-
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It contains detailed directions for collecting and preparing pei
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tages of the different me
Will no doubt find a place in every well-regu-
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A aroen Guide in aciono
PAUL G. HEINE
158 pages, interieaved, Ta 37 illastrations, 12mo, A net $1.50, postpaid $1,61
HS and n presentation of bacteriological technique, des
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By MICHAEL F. GUYER
250 pages, 8vo, cloth; net;$1.75, postpaid $1.88
ssi Paley of this book will explain its scope.
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It is intended as a laboratory
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ADDRESS DEPT. 64
Chicago
THE UNIVERSITY OF CHICAGO PRESS
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his is the specimen which Professor H. H. Wilder restored to approximately its
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The restored subject fina been molded and cast in our laboratory. The head
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Man of Spy No. 1 includes calvarium, lower jaw, right sup. max., portions
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ANATOMICAL LABORATORY OF CHARLES H. WARD
_ « THE LENNOX,” WEST AVENUE ROCHESTER, N. Y°
Nanana a
eee ee
VOL. XLIV, NO. 525 SEPTEMBER, 1910
THE
AMERICAN
NATURALIST
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences’ with
Special Reference to the Factors of Evolution
CONTENTS
Page
Nuclear sins sn of oranz EE in = sonatas Dr. Demers
MOORE D
Nuclear penne of oe ER in ee Sager R. "a
HARPER
tal
ki
H
533
III. The Pose of the Sauropodous Dinosaurs. Dr. W. D. MATTHEW - - -547
IV. Shorter Articles mest Discussion : Evolution wane mee Dr. es
Gu Retroactive Selection, CASPER L, oe The Logie o f Chance
in Problems of Generis, ARTHUR 8. DEWI
Notes and Literature: ry Kokma and Habits, _ Professor G. H. PARKER.
Plant Physiology, C. L. - BT
s
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THE
AMERICAN NATURALIST
Vou. XLIV September, 1910 No. 525
NUCLEAR PHENOMENA OF SEXUAL REPRO-
DUCTION IN ALG At!
DR. BRADLEY MOORE DAVIS
CAMBRIDGE, Mass.
CytToLocicaL investigations among the alge upon the
processes of gametogenesis and the developments that
follow upon the fusion of gametes have not been numer-
ous and are all of comparatively recent date. The diffi-
culties of obtaining and handling material in critical
stages require great patience, but the importance of the
problems has attracted attention to a field of enquiry in
which considerable progress has already been made and
which offers some of the most attractive problems for
cytological investigation. There has been a very marked
advance in our understanding of the Rhodophycew and
Phæophyceæ, but the Chlorophycee have so far received
little attention.
The advance has been chiefly in our interpretation of
certain life histories in which complex developments fol-
low upon the phase of sexual reproduction. The publi-
cation in 1894 of Strasburger’s paper on ‘‘The Periodice
Reduction of the Number of Chromosomes in the Life
History of Living Organisms’’* marked the beginning of
that closer analysis of the life histories of the higher
plants which presents the strongest support for the
1A paper read by invitation before the Botanical Society of America,
Boston, December 30, 1909.
2 Ann. of Bot., Vol. VIII, p. 281, 1894.
513
514 THE AMERICAN NATURALIST [Vou. XLIV
theory of antithetic alternation of generations. The
higher plants were naturally the first which were sub-
jected to critical cytological investigation and the struc-
ture and behavior of the nuclei through various stages
of ontogeny have been studied in an increasing number
of forms representative of the most important groups.
Later came the pioneer work of this character upon the
thallophytes which has given such rich returns in our
appreciation of the significance of the critical stages in
the complex life histories of certain types of the Asco-
mycetes, Urediner, Phæophyceæ and Rhodophycee.
It is the writer’s part in this symposium to outline the
advances that have been made in cytological research on
the sexual reproduction of the alge, and such enquiry,
for a number of reasons, necessarily leads at once to the
consideration of life histories with reference to cytolog-
ical detail. From studies upon the bryophytes, pterido-
phytes and spermatophytes we have learned that in these
groups every sexual nuclear fusion marks the beginning
of a distinct phase in the life history, the sporophyte, the
nuclei of which carry the double, or diploid, number of
chromosomes characteristic of the species. Furthermore,
we know that the sporophytic phase comes to an end with
the numerical reduction of the chromosomes to the orig-
inal, or haploid, number peculiar to the gametophyte.
This significant period of chromosome reduction is asso-
ciated in the bryophytes and pteridophytes with the for-
mation of spores, in the spermatophytes with the forma-
tion of pollen grains and embryo sacs. Every sexual
fusion, then, carries with it a prospective period of
chromosome reduction.
Since such is the history for the higher plants we have
every reason to expect that each sexual nuclear fusion
among the thallophytes with the resulting doubling of the
chromatin content in the zygote would be followed sooner
or later by reduction phenomena. It becomes a matter
of importance to determine when the latter event occurs,
since between the time when the gametes fuse and that of
No. 525] SEXUAL REPRODUCTION IN ALGE 515
chromosome reduction there is always the possibility of
an intercalated sporophytie phase in the life history, the
development of which will involve the mitoses of nuclei
that carry twice the number of chromosomes character-
istic of the sexual plant. From this point of view let us
then consider in the order of the Chlorophyceæ, Phæo-
phycee and Rhodophycew some of the recent cytological
research which has made much clearer the significance
of the life histories of certain important types.
There are in the life histories of a number of the green
alge certain outward signs that would lead one to sus-
pect that the period of chromosome reduction in these
forms takes place just previous to or during the germi-
nation of the zygospores or oospores. Thus the forma-
tion of several zoospores within the zygote of Ulothrix
and Hydrodictyon, and of four zoospores in the oospore
of Edogonium at once excites suspicion that the first
mitosis in these sexually formed cells is a reduction divi-
sion. Still more striking is the phenomena described in
the zygospores of the Conjugales where the fusion nu-
cleus by two mitoses gives rise to four daughter nuclei,
_ three of which in Spirogyra and two of which in the des-
mids Closterium and Cosmarium break down. Such be-
havior, involving a sacrifice of protoplasmic structure
and energy, is not easily understood except that it be
related to important events of ontogeny and phylogeny.
Any one familiar with the cytology of spore formation
in the higher plants or with oogenesis in animals would
at once suspect that the zygospore of the Conjugales was
the seat of reduction phenomena.
That this is really true has been shown by recent work
of Karsten? who has followed the chromosomes of Spiro-
gyra jugalis through the two mitoses within the zygo-
spore. Karsten in agreement with Berghs reached the
conclusion that the chromosomes in the resting nucleus
3 Karsten, G., 1908, "Die sapre g R von Spirogyra
jugalis Ktzg.,’’ Flora, Vol. XCIX, p. 1, 190
516 ` THE AMERICAN NATURALIST [ Vou. XLIV
‘of Spirogyra lie in the substance of the large nucleole.*
He was able by the proper extraction of stain to differ-
entiate fourteen bodies in the gamete nucleus which cor-
responded in number to the fourteen chromosomes that
may be readily counted for this species in later mitoses.
The union of the gamete nuclei in the zygospore involves
the fusion of the two nucleoles to form a dense homo-
geneous structure in preparation for a characteristic as-
sociation of the two sets of chromosomes, one derived
from each parent.
The approach of the first mitosis is indicated by
changes within the fusion nucleole where a granular
structure begins to appear, accompanied by irregulari-
ties in its form. As these changes proceed an assemblage
of deeply staining bodies becomes evident which in later
stages are readily identified as chromosomes. There are
twenty-eight of these grouped in fourteen pairs, an ar-
rangement which is characteristic of a phase of chromo-
some reduction that follows synapsis and which signifies
that the chromosomes are to be distributed in two sets
of equal numbers by the following mitosis. This dis-
tribution occurs in Spirogyra and the second mitosis in
the zygospore is concerned with the reduced, or haploid,
number of chromosomes. Thus the double, or diploid,
number is present only in the fusion nucleus; the numer-
ical reduction takes place with the first mitosis. There
are no nuclear divisions in which the diploid number of
chromosomes is passed on, and assuming that the sporo-
phyte generation is characterized by nuclear divisions
with the diploid number of chromosomes, there is no
sporophytie phase in this life history.
So close is the parallelism between the events of reduc-
tion in Spirogyra and those of higher plants that Karsten
‘even reports evidence for the premature division of the
chromosomes during the first mitosis in preparation for
‘B. F. Lutman has, however, recently reported (Science, Vol. XXXI, p.
633, 1910) that the chromosomes of Closterium are formed from a spirem
which has its origin in the fine reticulum around the nucleole.
No. 525] SEXUAL REPRODUCTION IN ALGÆ 517
the second division, a phenomenon very characteristic
of the reduction divisions of higher plants. The degen-
eration of three of the four nuclei which result from the
two mitoses within the zygospore of Spirogyra is of
course an illustration of that conservation of material for
a single reproductive cell which finds its analogy in the
history of development of certain megaspores at the ex-
pense of their neighbors and in the maturation of the
animal egg. ,
It seems probable that studies upon the germinating
zygospores and oospores of other green alge will estab-
lish them to be the seat of reduction phenomena similar
to that described above, although such investigations are
beset with many technical difficulties. It is to be hoped
that we may soon have information on these conditions
in such types as @dogonium, Spheroplea, Chara and
Vaucheria. The complexities reported in the formation
of auxospores among the diatoms take on new interest
in relation to the conditions in Spirogyra. In none of
these forms have we at present any reason to expect the
presence of a sporophytic generation.
Coleochate has long been regarded as a type of pecul-
iar interest chiefly perhaps because its oospore on ger-
mination gives rise to a small group of cells, each of
which develops a zoospore. It is not strange that this
cellular structure, a phase intercalated between two sex-
ual plants, should have been compared with the simplest
types of sporophytes in the liverworts, and that in at-
tempts to bridge the gap between the thallophytes and
bryophytes Coleochete should have been brought for-
ward as illustrating the primitive beginnings of a sporo-
phyte generation.
A eytological study by Allen® on the germination of the
oospore of Coleochete, however, presents evidence that
the first mitosis in the oospore is a reduction division
and that consequently the later mitoses can not be sporo-
š Allen, C. E., 1905, ‘‘Die Keimung der Zygote bei Coleochete,’’ Ber.
` deut. bot. Gesell., Vol. XXIII, p. 286, 1905.
518 THE AMERICAN NATURALIST [ Vou. XLIV
phytic in character. Allen found that when the fusion
nucleus made preparations for the first mitosis the chro-
matic material previously in the form of an irregular net-
work gathered at one side of the nucleus in the manner
characteristic of synapsis. There was evidence of a pair-
ing of the chromatic threads during the process of synap-
sis which is interpreted by this author as indicating a
pairing of the chromosomes from the two gamete nuclei.
Following synapsis the chromatic material becomes dis-
tributed as a coiled thread from which the chromosomes
are differentiated, that in a later stage are found scat-
tered through the nuclear cavity. A count of the chro-
mosomes at this stage indicated that the number thirty-
two is the double or diploid number for the species
studied. Some of the chromosomes were clearly as-
sociated in pairs, a condition that becomes more evi-
dent in later stages when at metaphase of the first
mitosis the now much condensed chromosomes are as-
sembled at the equatorial plate. In this mitosis the chro-
mosomes are short and thick, in sharp contrast to the
long narrow bent rods which are characteristic of the
second mitosis. Allen then bases his conclusion that the
first mitosis in the oospore is a reduction division chiefly
on the presence of a stage similar to synapsis preceded
by a long resting period, and on peculiarities in the form
and grouping of the chromosomes, which peculiarities
are similar to those of the heterotypie division in higher
plants.
It would seem then that Coleochete can no longer be
considered as a type very helpful in considerations. of the
origin of the sporophyte or suggestive of affinities with
the archegoniates. With respect to the latter point the
simple unicellular character of the sexual organs offers
further difficulties to a relationship to the archegoniates,
since the multicellular archegonia and antheridia of this
last group apparently require an origin from a multicel-
lular type of sexual organ such as is best illustrated
among living forms by the plurilocular sporangia and
No. 525] SEXUAL REPRODUCTION IN ALG 519
gametangia of the Phaeophyceae. The writer has dis-
cussed this problem in a paper on ‘‘The Origin of the
Archegonium,’’® and advanced the view that the arche-
gonium and antheridium arose from some type of pluri-
locular sporangium or gametangium through the differ-
entiation, in response to terrestrial life habits, of a sterile
protective envelope around the gametes. Schenck in a
contribution ‘‘Ueber die Phylogenie der Archegoniaten
und der Characeen’’* accepts the above view and even
argues for a direct descent of the archegoniates from
the Phæophyceæ, carrying the speculation far beyond the
point with which the writer is in agreement. A discus-
sion of the difficulties which face Schenck’s hypothesis
would, however, lie outside of the province of this paper.’
Assuming that the sporophyte is normally character-
ized by mitoses concerned with the diploid number of
chromosomes, the results of the recent research on the
Chlorophyecee make it appear probable that none of the
known living types present an alternation of generations
even in its simplest form. The striking differences be-
tween the Chlorophycee and the simplest archegoniates
have become more strongly emphasized by the latest re-
search.
Passing to the Phæophyceæ we shall have to consider
cytological conditions and life histories very much more
complicated than any that are known for the Chloro-
phyceæ. Only the specialist among the alge can fully
appreciate the diversity of the types and lines of develop-
ment in the large assemblage of forms termed the brown
alge. The chief groups exhibit greater differences
among themselves than do the divergent lines among the
green alge. Unfortunately our information on the cytol-
ogy of reproduction in the Pheophycee is limited to three
groups, the Dictyotales, Fucales and Cutleriacee, groups
which occupy isolated positions of problematical rela-
tionship to the lower forms of the Phæophyceæ.
e Ann. of Bot., Vol. LXVII, p. 477, 1903.
* Engler’s Botan. Jahrbücher, Vol. XLII, 1908.
*See review by Davis, AMER. NAT., Vol. XLIII, p. 107, 1909.
520 THE AMERICAN NATURALIST [ Vou. XLIV
We have from the investigations of Williams® an ac-
count of the cytology of Dictyota throughout the critical
phases of its life history. There are three forms of this
alga, the male and female sexual plants and an asexual
plant which develops spores in groups of four (tetrads)
within a tetrasporangium. Earlier research of Mottier
indicated clearly that the tetraspore mother-cell is the
seat of chromosome reduction, and Williams by studies
of the sexual plants as well as the asexual was able to
present convincing cytological evidence of an alternation
of generations.
Williams found that the sexual plants were character-
ized by nuclei with sixteen chromosomes and that this
number was passed on to the eggs and sperms respec-
tively. Fertilization takes place following the discharge
of the gametes, which have the peculiarity of being de-
veloped in fortnightly crops, ‘‘each crop being initiated a
little before the lowest neap tide, and arriving at matur-
ity about the period of the highest succeeding spring
tide”. The motile sperms gather about the eggs which
for a short time exert a strong chemotactic influence.
Following the union of the gamete nuclei, a second nu-
cleole appears in the fusion nucleus which Williams be-
lieves to be the chromatin brought by the sperm. The
first mitosis in the egg presents thirty-two chromosomes
at the equatorial plate, and this is believed to be the first
mitosis of a sporophyte generation represented by the
asexual plant and terminating with the development of
the tetraspores.
The spindle poles of the first mitosis in the eggs ap-
pear to arise by the division of an aster the two poles of
which separate until they come to lie on opposite sides of
the nucleus. It is an interesting fact that unfertilized
eggs begin a parthenogenetic development, but the spin-
* Williams, J. Lloyd, 1904, ‘‘Studies on the Dictyotacew.’’ 1., ‘The
Cytology of the Tetrasporangium and the Germinating Tetraspore,’’ Ann.
of Bot., Vol. XVIII, p. 141, 1904. TI., ‘‘ The Cytology of the Gametophyte
Generation,’ ’ Ann. of Bot., Vol. XVIII, p. 183, 1904.
No. 525] SEXUAL REPRODUCTION IN ALGZ 521
dies of the first mitosis are multipolar and the chromo-
somes are distributed irregularly to a cluster of small
nuclei. It would seem then either that the sperm brings
to the egg a directive element in the form of an aster,
which gives polarity to the fusion nucleus, or that in the
absence of fertilization the egg is unable to develop the
mechanism necessary for a normal mitosis.
It is the purpose of this paper to consider the nuclear
phenomena of sexual reproduction among the alge in the
broadest sense, and this must involve the consideration
of any sporophytie generation when present. It has be-
come clearly established by the cytological research of
recent years that the sporophytic phase in a life history
is a period during which one of the final ends of a sexual
nuclear fusion, the intimate association of the sets of
parental chromosomes, is delayed and in consequence the
mitoses of this period deal with double the number of
chromosomes present in the sexual plants. Williams
found in the case of Dictyota that the mitosis which cuts
off the tetraspore mother-cell presented the same large
number of chromosomes as the first division of the egg,
i. e., twice the number characteristic of the sexual plants.
The inference is clear that the vegetative mitoses
throughout the development of the asexual plant must be
sporophytie in character, and that this generation must
have developed from the fertilized egg.
With respect to the two mitoses within the tetra-
sporangium, the main events are evidently those char-
acteristic of a numerical reduction of the chromosomes.
There is a stage of synapsis in which a long thin spirem
is found closely coiled in knots against the nuclear mem-
brane. Following this comes a loosening up of the spirem
and the differentiation of sixteen chromosomes, the re-
duced number. The form of the chromosomes, which are
loops and closed rings, indicates at once to one familiar
with the peculiarities of the heterotypie mitosis that
these structures are really pairs of sporophytie echromo-
somes (bivalent chromosomes) in close association.
522 THE AMERICAN NATURALIST [ Vou. XLIV
The members of each pair are separated by the first
mitosis which thus distributes the thirty-two chromo-
somes in two sets. The second mitosis (homotypic) pre-
sents sixteen simple chromosomes in the form of bent
rods, similar to those found in the gametophytes. The
cytological evidence justifies the conclusion that the
tetraspores give rise to the sexual plants and that the
fertilized egg must develop the asexual plant, and thus
is established an alternation of generations.!°
The peculiarities of the life history of Fucus in rela-
tion to the life histories of plants in general are most
striking. It became evident from the studies of Stras-
burger in 1897 and of Farmer and Williams in 1896-98
that the mitoses within the oogonium presented only half
the number of chromosomes which were present in the
vegetative cells of the Fucus plant. This placed the
period of chromosome reduction just previous to the dif-
ferentiation of the gametes, a condition that is not known
in any other group of the thallophytes. To bring such a
life history into relation with the prevailing conditions
in the lower plants becomes a most interesting problem
of plant morphology and phylogeny.
We have recently had from Yamanouchi! a much more
detailed account of the reduction processes in Fucus than
the descriptions of the earlier writers. The nucleus
within the young oogonium passes through a remarkably
clearly defined stage of synapsis during which chromatic
threads, derived from a reticulum, become arranged in
loops that are gathered together closely attached at one
* Since the above was written W. D. Hoyt (Bot. Gaz., Vol. XLIX, p. 55,
1910) has announced his success in raising from the fertilized eggs of
Dictyota dichotoma fruiting plants which proved to be asexual siete
and from the tetraspores sexual plants both male and female. Thus
conclusions based upon cytological evidence have been sustained by qiw
studies.
of marine alge, but it is to be hoped that Hoyt’s success with Dictyota
will lead to further studies of this character, especially upon forms of the
Rhodophyceæ
Vaihansiechi; S., 1909, ‘‘ Mitosis in Fucus,’’ Bot. Gaz., Vol. XLVII.
p- 173, 1909.
No. 525] SEXUAL REPRODUCTION IN ALG 523
side of nuclear membrane. Close to this point but out-
side of the nuclear membrane, there is developed an ac-
cumulation of kinoplasm from which is differentiated an
aster with a ehrontdgome, so that the nucleus during
synapsis exhibits strongly marked polarity.
The chromatic loops extend into the nuclear cavity and
sections show them to be thirty-two in number. After a
period of condensation each loop is transformed into a
pair of chromosomes by the separation of the arms at the
bend. The pairs of chromosomes then become scattered
through the nuclear cavity (diakinesis). The interpreta-
tion of this history is that the sixty-four somatic chromo-
somes of the Fucus plant are arranged end to end on the
spirem and become associated in thirty-two pairs through
the formation of the loops. Meanwhile a second aster
appears, apparently arising de novo, generally at some
distance from the first, and the two asters establish the
poles of the first spindle. The thirty-two pairs of chro-
mosomes are gathered at the equatorial plate and the
members of the pairs distributed in two sets, thus affect-
ing a numerical reduction by one half of the sixty-four
somatic chromosomes.
There is apparently no premature division of the chro-
mosomes in preparation for the succeeding division, as is
generally the case in the heterotypic mitosis. The sec-
ond and third divisions in the oogonium are similar in all
essentials to typical mitoses. They deal, of course, with
thirty-two chromosomes, the haploid number, which
divide lengthwise during the metaphase of each mitosis.
There is a long period of rest following the second
mitosis. The first mitosis in the antheridium is likewise
a reduction division similar to that in the oogonium and
need not be described in this connection,
The nucleus of the unfertilized egg exhibits no evi-
dence of polarity, but following the entrance of the sperm,
according to Yamanouchi, an aster with a centrosome
becomes at once evident. A second centrosome with
radiations appears later at the point where the sperm
524 THE AMERICAN NATURALIST [ Vou. XLIV
fuses with the egg nucleus. These two asters es-
tablish the spindle poles of the first mitosis, which pre-
sents sixty-four chromosomes. The chromatin of the two
gametes is indistinguishable in the fusion nucleus.
The interpretation of the life history of Fucus with its
phase of chromosome reduction so close to the differen-
tiation of the gametes involves great difficulties. Stras-
burger has long held the thallus of this plant to be a sporo-
phyte generation, assuming that the gametophyte phase
is represented by the third mitosis in the oogonium and
the few antheridial mitoses which follow the reduction
division. He would then regard the antheridia and
oogonia to be derived not from primitive sexual organs,
but from sporangia corresponding to the tetrasporangia
of Dictyota. This view involves a reversal of the rela-
tions between the gametophyte and sporophyte genera-
tions usual among the alge, since it supposes the almost
complete suppression of the gametophyte. However in-
teresting and suggestive is this interpretation, it can
hardly be considered other than a speculation until we
know more of the probable phylogeny of the Fucales.
It has been evident for a number of years that the
life history of the Cutleriaceew probably involved
two phases represented by sexual and asexual plants,
respectively, and there has accumulated much evi-
dence from the studies of Reinke, Falkenberg, Sau-
vageau, Church and others indicating that these
phases present a true alternation of generations. The
forms most studied have been Cutleria multifida
with a large much branched thallus which develops
gametes, and Aglaozonia reptans, a small crustaceous
alga which reproduces by zoospores. On the germination
of the zygotes and zoospores of these types forms are
produced which very shortly take on vegetative char-
acters not of the parent plants, but from the zygotes
arise Aglaozonia-like sporelings and from the zoospores
sporelings totally unlike A glaozonia, but with characteris-
ties of Cutleria. Upon this behavior chiefly have been
No. 525] SEXUAL REPRODUCTION IN ALG 525
based the suggestions of an alternation of generations in
the Cutleriacee.
A preliminary paper by Yamanouchi’? on the above
named species presents cytological evidence in support
of the theory that they are sexual and asexual phases, re-
spectively, of the same life history, with the relation one
to the other of gametophyte and sporophyte. The vege-
tative mitoses of Cutleria multifida and those leading to
the formation of the male and female gametes show uni-
formly twenty-four chromosomes. The zygote develops
at once into a sporeling, the nuclei of which have forty-
eight chromosomes. There is thus no reduction of the
chromosomes at the time of the germination of the zygote,
and the sporeling which results must be considered as
sporophytiec in character.
The vegetative mitoses of Aglaozonia reptans exhibits
forty-eight chromosomes, but the nuclear divisions within
the sporangia are quite different. Following the differ-
entiation of a sporangium, the nucleus passes through a
stage of synapsis in which the chromatic spirem is ar-
ranged in a series of loops from which are developed
twenty-four bivalent chromosomes. The first division in
the sporangium is therefore a heterotypic mitosis. Later
mitoses in this cell exhibit the reduced number of chro-
mosomes. Since sporogenesis in Aglaozonia is accom-
panied by reduction phenomena, there must be in its life
history a sexual phase of which it is the sporophyte gen-
eration, and the number of chromosomes as well as other
details of cell structure present strong cytological evi-
dence that the gametophyte is Cutleria. Such evidence
supporting the conclusions of the earlier writers based
on the seasonal habits of Cutleria multifida and Aglao-
zonia reptans and on the structure of the respective
sporelings, makes as strong a case for an alternation of
generations in the Cutleriacee as is possible short of the
actual cultivation of these alge from zygotes and zoo-
spores to fruiting maturity.
2 Yamanouchi, S., 1909, ‘‘Cytology of Cutleria and Aglaozonia,’’ Bot.
Gaz., Vol. XLVIII, p. 380, 1909.
526 THE AMERICAN NATURALIST [ Vou. XLIV
These results from studies on the three most highly
differentiated groups of the Pheophycee (Dictyotales,
Fucales and Cutleriacee) indicate how complex has been
the evolutionary history of the divergent phyla as-
sembled under this name, and how difficult are likely to
be the problems of tracing their relationship to lower
groups of the brown alge.
Perhaps in no assemblage of the alge have the cyto-
logical studies of recent date given such striking results
as in the Rhodophycee. Our understanding of the life
history of these forms has been quite revolutionized by
the research of three investigators, Wolfe, Yamanouchi
and Lewis.
Wolfe!’ from studies on Nemalion determined for this
type that the sexual organs are not simple uninucleate
cells, since the trichogyne possesses a nucleus in addition
to that in the carpogonium and the sperm is binucleate
and the homologue of the antheridium. The cells of the
eystocarp following the fertilization of the carpogonium
have nuclei with approximately sixteen chromosomes
which is double the number present in the vegetative
cells of the parent plant. The cystocarp must then be
regarded as sporophytic in character. Because the
mitotice figures in advanced stages of the cystocarps
showed certain peculiarities Wolfe concluded that a re-
duction of the chromosomes occurred preliminary to the
development of the carpospores. However, he did not
trace a process of chromosome reduction through the
characteristic phase of synapsis followed by a hetero-
typic mitosis, and on this point of his investigation more
evidence is to be desired. There are certain reasons
why in life histories among the Rhodophycee of the type
of Nemalion the process of chromosome reduction may
be expected to occur at the time of the germination of the
carpospore.
* Wolfe, J. i 1904, ‘‘ Cytological Studies on Nemalion,’’ Ann. of Bot.,
Vol. XVIII, p. 608, 1904.
No. 525] SEXUAL REPRODUCTION IN ALG 527
The investigations of Yamanouchi't on Polysiphonia
established the important fact that the carpospore of this
form retained the diploid number of chromosomes
(forty) present throughout the sporophytic tissue of the
eystocarp, and gave rise to a sporeling bearing this num-
ber in its nuclei. Furthermore, the tetrasporic plants
were found to be diploid in character and the presence of
the period of chromosome reduction was established in
the tetraspore mother-cell. The nucleus of the tetra-
spore mother-cell passes through a clearly defined stage
of synapsis, following which the forty sporophytic chro-
mosomes are found associated in twenty pairs (bivalent
chromosomes). The first mitosis distributes the members
of these pairs and is therefore a reduction division. The
tetraspore has then the haploid number of chromosomes
(twenty) and on germination develops a sporeling with
this reduced number, which was found to be characteris-
tic of the sexual plants. It is reasonable to conclude that
in the life history of Polysiphonia the sexual plants alter-
nate with the tetrasporic, each phase arising from the
spores produced upon the other. Yamanouchi expressed
the belief that ‘‘the sexual plants and tetrasporiec plants
present two distinct phases of an antithetic alternation
of generations, with the cystocarp a part of the sporo-
phytic phase’’.
The many interesting points in the history of the de-
velopment of the sexual organs and the cystocarps are
too detailed to be presented in this brief review. Yama-
nouchi, however, supports Wolfe’s conclusion that the
trichogyne in early stages of development contains a
nucleus, and that the sperm is the homologue of an anthe-
ridium, although in Polysiphonia this cell is uninuculeate.
Some criticisms of Kurssanow'® on the work of Wolfe
upon these latter points must also be omitted.
" Yamanouchi, S., 1906, ‘‘ The Life History of Polysiphonia,’’ Bot. Gaz.,
XLII, p. 401, 1906.
* Flora, Vol. XCIX, p. 111, 1909,
528 THE AMERICAN NATURALIST [ Vou. XLIV
A detailed study by Lewis'® of the life history of Grif-
fithsia is in agreement with the results of Yamanouchi
on the essential facts of an alternation of sexual and
tetrasporic plants and the behavior of the chromosomes
throughout the various phases of the similar life his-
tories. The sexual plants have seven chromosomes, the
haploid number. The eystocarp presents nuclei with
fourteen chromosomes and is clearly a sporophytic phase
which, as in Polysiphonia, develops with the cooperation
of the cytoplasm in certain cells of the gametophyte; the
carpospores have fourteen chromosomes. The tetra-
sporie plants are characterized by fourteen chromosomes,
the diploid number, and may be assumed to arise from
the carpospores. The first mitosis in the tetraspore
mother-cell is a reduction division preceded by the char-
acteristic stage of synapsis from which the chromosomes
emerge in seven pairs. Seven chromosomes, therefore,
pass to the tetraspores from which the sexual plants
may be expected to develop.
It is known that in a number of species of red alge
structures resembling tetraspores are occasionally found
on sexual plants and that proearps are sometimes pres-
ent on tetrasporic individuals. Such conditions, first ob-
served by Bornet, have more recently been noted by
Lotsy for Chylocladia kaliformis, Yamanouchi for Poly-
siphonia violacea, Lewis for Griffithsia Bornetiana, and
by the writer for Spermothamnion Turneri, Callitham-
nion Baileyi and Ceramium pedicillatum. Furthermore,
certain of the red alge, as Rhodymenia palmata on the
New England coast, present tetrasporiec plants in great
abundance, while cystocarpic individuals are rare or un-
known. Certain critics see in the above phenomena seri-
ous difficulties for the theory of alternation of genera-
tions in the Rhodophyceew so strongly supported by the
work of Yamanouchi and Lewis.
These authors had only limited material of what seemed
* Lewis, I. F., 1909, ‘*The Life ead of Griffithsia Bornetiana,’*
Ann. of Bot., Vol. XXIII, p. 639, 1909
No. 525] SEXUAL REPRODUCTION IN ALGZ 529
to be tetraspore mother-cells on sexual plants, but in this
material the apparent tetrasporangia failed to mature
tetraspores, the cleavage furrows proceeding only a short
distance into the mother cells while the nuclei either re-
mained undivided (Polysiphonia) or produced groups of
several nuclei (Grifithsia). Thus such cytological evi-
dence as we have on these irregularities indicates them
to be abnormal developments. Examples of apogamy
and apospory are now recognized as by no means uncom-
mon in the higher groups of plants exhibiting alternation
of generations, and it will not be at all surprising if such
phenomena or related irregularities of life history are
found among the Rhodophycex. Such peculiarities must
of course be thoroughly studied to determine whether or
not they will prove to be the exceptions that support the
rule. The investigations of recent years on apogamy
and apospory in the pteridophytes have in no way weak-
ened the acknowledged alternation of generations in that
group.
A very interesting problem is presented in the phe-
nomenon described by Osterhout!* of the germination of
the tetraspores of Agardhiella tenera (Rhabdonia tenera)
while still imbedded in the tissue of the parent plant. A
peculiarity of this development is the behavior of the
group of tetraspores as a unit, so that all four cells enter
into the formation of a sporeling. It is important to
note that the sporelings are very commonly sexual plants,
as would be expected from the germination of normal
tetraspores. It seems quite possible that the occasional
tetrasporie shoots reported by this author are products
of a tetraspore mother-cell in which the reduction mitoses
have been suppressed, and therefore the tetrasporang-
ium, behaving like a monospore, would naturally give rise
to a tetrasporic plant. This is a problem which should be
investigated, because if the above suggestion prove true,
this behavior of the tetraspores of Agardhiella would
* Osterhout, W. J. V., 1896, ‘‘Life History of Rhabdonia tenera J.
Ag.,’’ Ann. of Bot., Vol. X, p. 403, 1896.
530 THE AMERICAN NATURALIST [ Vou. XLIV
present strong evidence in support of the theory of alter-
nation of generations in the Rhodophycee. The peculi-
arity of Rhodymenia palmata on the New England coast,
referred to above, may likewise rest upon a suppression
of reduction phenomena in the tetrasporangium which
would lead to the omission of the sexual phase from the
life history and permit of an indefinite succession of
tetrasporic plants.
It is very important that the life histories of some of
the simpler red alge be investigated, especially such
forms as have Chantransia-like stages characterized by
the production of monospores. The fact that the reduc-
tion divisions of Polysiphonia and Griffithsia are not. as-
sociated with the formation of carpospores leads one to
suspect that the period of chromosome reduction in such
types as Batrachospermum and Nemalion may occur at
the time of the germination of the carpospore. Should
this prove to be the case, the origin of the tetrasporic
phase, characteristic of the higher Rhodophycer, may
without difficulty be conceived as the result of a post-
ponement of the reduction divisions and their associa-
tion with a type of cell similar to and perhaps identical
with a monosporangium. Such a postponement or
delay in the expression of the reduction divisions would
establish at once a plant with the diploid number of chro-
mosomes (tetrasporic plant) and introduce into the life
cycle the tetrasporangium as a new type of reproductive
organ.
Lewis regards the tetrasporic plant as illustrative of
‘‘an homologous alternation of generations, not the
equivalent, wholly or in part, of the sporophyte of the
archegoniates’’, and he thereby limits the sporophytic
phase in the life history to the sporogenous cells of the
eystocarp. This conclusion is based on the morphological
resemblance of the tetrasporic plants to the sexual, al-
though Lewis himself points out important differences
between the two. Thus ‘‘tetrasporic plants (of Griffith-
sia Bornetiana) are always more abundant, as well as on
No. 525] SEXUAL REPRODUCTION IN ALG 531
the average larger than sexual plants’’ a condition which
is true of a number of species of the Rhodophycee with
which the writer has had a rather extensive field ac-
quaintance. This is a point of some importance, since too
great emphasis may be placed on the resemblance in form
between the two generations (a resemblance which seems
most natural since the plants develop under closely sim-
ilar life conditions), and important differences in size,
dimensions of the cells, and general vegetative vigor
may not receive the attention that they deserve. If the
fusion of gamete nuclei is to be regarded as the stimulus
to a sporophytie generation, the period of chromosome
reduction is equally characteristic of its end, and the sec-
ond event follows as a natural consequence upon the first.
Mitoses with the diploid number of chromosomes when-
ever they oceur between these two events furnish, in the
opinion of the writer, the only safe criteria of the extent
and duration of a sporophytie generation in normal life
histories,
Yet it has become clear from recent research on apog-
amy and apospory that the mere number of chromo-
somes, whether haploid or diploid, does not determine the -
morphology of the generation, gametophyte or sporo-
phyte, with which they are associated. The reasonable-
ness of this principle is apparent when regarded from
another point of view. The inheritance which is respon-
sible for the development in a type of a sporophyte gen-
eration must be carried by the sexual phase, and the
potentialities of a sexual generation must be present in
the sporophyte, although in normal life histories the in-
heritance is latent at certain stages and only becomes
operative in both generations after definite periods of
development have been passed. The two germ cells, eggs
and spores, do not give rise to different generations be-
cause they expressly contain a single or a double set of
the chromosomes characteristic of the species; the causes
of their respective developments are too complicated to
be expressed in such simple terms.
532 THE AMERICAN NATURALIST [ Vou. XLIV
To the writer the differences between the egg and the
spore appear to be such as may depend primarily on a
greater vigor and vitality given to the egg by the fusion
of the gametes, a vigor which has expressed itself in such
varied morphological manifestations because of the dif-
ferent conditions under which the sporophyte generations
have become established in the numerous phyla char-
acterized by their presence. The conditions affecting the
sporophyte are not alone those of physical environment;
there are also those evolutionary factors that operate to
adjust the plant, as far as is possible, to its place among
other organisms. One conclusion stands out clearly
among the difficulties of these problems: as in the case of
sex, the sporophyte has probably arisen independently a `
number of times in the evolution of plants.
So we are brought to the end of our discussion of the
nuclear phenomena of sexual reproduction in the alge to
the problems of the origin of the sporophyte and the re-
lations of the sexual and asexual generations to one
another, whether or not they are essentially homologous
or antithetic in the alternation of generations. It is not
-the purpose of this symposium to consider these matters,
but allusions and inferences could not be kept out where
the vital connections between the subjects under consid-
eration and these larger speculations are so close. The
immediate need of such discussion is perhaps not so great
for the reason that the pages of the New Phytologist for
1909 have presented two important papers of Lang and
Blackman representing the opposite schools together with
a report of a discussion in which a number of the leading
British botanists took part. That the writer’s sympathies
are strongly with the hypothesis of antithetie alternation
of generations must have been apparent from the tenor
of this paper.
_ CAMBRIDGE, MASSACHUSETTS,
December, 1909.
NUCLEAR PHENOMENA OF SEXUAL REPRO-
DUCTION IN FUNGI’
PROFESSOR R. A. HARPER
UNIVERSITY OF WISCONSIN
In the light of recent researches the old dogma that the
parasitic mode of life tends to the disappearance of sex-
uality has practically disappeared at least so far as the
fungi are concerned. The evidence is now generally ac-
cepted that either a typical conjugation of normally dif-
ferentiated gametes and their nuclei or some form of sub-
stitute for it is everywhere present.
Ernst and Schmidt on the basis of their studies on the
root parasite Rafflesia have also recently emphasized the
fact that there is no evidence in the case of seed plants
that the parasitic habit tends to the disappearance of
sexuality. Farmer and Digby have described a most
remarkable substitute fusion in an apogamous fern and
a still more striking case of substitute cell and nuclear
fusions in another apogamous fern has been recently dis-
covered in my own laboratory. It is proper under these
conditions to examine anew and most critically all cases
of cell fusions with reference to their accompanying
nuclear phenomena and possible significance in the ee
cycle in question.
The study of sexuality in the fungi has also brought to
light some fundamental modifications of the process of
sexual fusion as found elsewhere which enlarge our con-
ception of the nature and significance of gametic unions.
It has also revealed most curious and striking substitu-
tions for sexual fusions. I shall review briefly the most
characteristic and significant of these variations from the
ordinary methods of sexual reproduction. The fusion of
1A paper read-by invitation before the Botanical Society of America,
Boston, December 30, 1909.
533
534 THE AMERICAN NATURALIST [Vou. XLIV
the ameeboid swarmspores to form the plasmodium of the
slime moulds has never been satisfactorily accounted for,
nor related to the processes either vegetative or sexual
in other groups of fungi. With the increase of our knowl-
edge of the possible variations which the sexual process
may undergo it is becoming more possible to accept the
conception that in some way the formation of the plas-
modium may represent either an incipient or an aberrant
type of gametic union in which the normal fusion of two
gametes is replaced by a massing of indefinitely numer-
ous cells.
The cytological study of the group is only just begin-
ning and doubtless much is to be corrected in the frag-
mentary observations already published. Olive, Jahn
and Kraenzlein, however, agree that there are evidences
of nuclear fusions either just before spore formation or
earlier in the formation of the fruit bodies, and that these
karyogamies are followed by synapsis and reduction
divisions. The figures given show that these forms have
typically developed nuclei which are favorable for fixing
and staining, and indicate that whatever disagreement
exists as to what occurs in the few types studied may be
expected to be cleared up by further work.
The older authors were loath to regard the union of
the ameebe to form a plasmodium as involving anything
of a sexual nature, but it is quite possible that we may
have to extend our conception of sexual fusions at least
in their primitive forms to include cases of multiple cell
fusions followed by vegetative growth, and finally the
fusion of the nuclei in pairs. That cell and nuclear fu-
sions may be thus widely separated is plain from the
conditions in the rusts, and in the slime moulds, as in the
rusts, nuclear fusion is followed shortly by the reduction
divisions.
We can not yet regard the nuclear phenomena in the
slime moulds as sufficiently cleared up. In the light of
- what has been found in other fungi there is however cer-
tainly no ground for believing that the nuclear history
No. 525] SEXUAL REPRODUCTION IN FUNGI 535
in the plasmodium is as simple as the older students be-
lieved.
As directly suggestive of what may be expected in the
slime moulds, we have the well-established fact of the
fusing of multinucleated gametes and the subsequent
pairing of all or approximately all their nuclei. Leger
and others have seen that the gametes of Sporodinia and
other zygomycetes are multinucleated, but the accounts
of the subsequent processes in the zygospore can not be
accepted as well founded and no one yet has been able to
trace the history of these minute nuclear granules.
Stevens, however, has established the entrance of many
male nuclei and their subsequent pairing with the numer-
ous nuclei of the eggs of Cystopus bliti and portulace
and unpublished observations made in my own labora-
tory have confirmed his results for C. bliti. I have also
found such multiple fusions of about 200 nuclear pairs in
the large oogonia of Pyronema. Claussen in a prelimi-
nary paper, while confirming the existence of the fusion
of multinucleated gametes and subsequent pairing of the
sexual nuclei in Pyronema, claims that the fusion of the
pairs is not completed till they reach the ascus.
The large size of the nuclei in the ascogenous hyphe
in Claussen’s preliminary figures seems to me, however,
to confirm my own conclusion that the fusion is already
completed at this stage. These multinucleated gametes
prove convincingly that our conception of the egg and
male cell must be extended to include multinucleated as
well as uninucleated types. The cell at the moment of
sexual union may be multinucleated as well as in its ordi-
nary vegetative stages in the hyphæ, ete. That the
nuclei fuse in pairs and not in larger numbers is further
convineing evidence that they are the real bearers of the
idioplasm and that the constancy of the chromosome num-
ber must be maintained by the ordinary type of doubling
and subsequent reduction.
With the demonstration of the existence of coenocytic
gametes the nature of the coenocyte itself becomes still
536 THE AMERICAN NATURALIST [ Vou. XLIV
clearer, as I have elsewhere pointed out. The continuous
plasma membrane enclosing a coenocyte is plainly in its
relation to the other cell contents to be compared with
the same structure in an uninucleated cell rather than with
the aggregate of membranes which bound off a mass of
tissue from its environment and the cells of the tissue
from each other.
It is further most interesting to note that De Bary’s
conception of the male element in the oomycetes as gono-
plasm, a mere unbounded portion of the contents of the
antheridium, has been entirely confirmed by subsequent
cytological research, and it is further proof of the super-
ior significance of the nucleus as the carrier of the idio-
plasm in sexual fusions that in such forms as Cystopus
candidus, for example, it is merely one of the several
nuclei in the antheridium, and that with no definitely
limited cytoplasmic unit which migrates through the
conjugation tube and fertilizes the egg. The differentia-
tion of the male gamete is not here an ordinary process
of cell division, but a mere flowing out of one of the
nuclei of the coenocytic antheridium.
The most striking discovery as to fusion in the fungi
and the one which preceded and led the way to very many
of the more important later results was the observation
by Wager of paired nuclei and the subsequent fusion of
these nuclei in the young basidium.
Wager was mistaken in describing a series of such
fusions by pairs, but the clear account of the nuclear
structures which he gave and the evidence that nuclear
division occurs by a karyokinesis like that of other plants
and animals showed for the first time the possibility of
determining the nature of the various reproductive bodies
in fungi by a more exact cytological investigation of them
than had before been thought possible.
Wager brought the first proof of the existence of an
endokaryogamy—the fusion of nuclei not derived from
separate and independent gametes as in ordinary fer-
tilizations, but having had a similar if not identical his-
No. 525] SEXUAL REPRODUCTION IN FUNGI 537
tory in the cells from which the basidium arose. Such a
process was entirely unknown before in either plants or
animals.
Subsequent investigations by Dangeard, Maire, Ruh-
land, Nichols, myself and others have shown that in the
Basidiomycetes a long series of binucleated cells pre-
cedes the formation of the basidium and the nuclear
fusion in it may well have something of the value of a
union of differentiated gametic nuclei.
The origin of the binucleated cells in the Basidiomy-
cetes does not apparently result from a cell fusion at a
definite point in the life cycle, as is the case in the æcid-
ium of the rusts. Such a fusion might perhaps be ex-
pected to be effected at the origin of the carpophore, but
it has been established that binucleated cells may be
present in the mycelium prior to the formation of the
carpophore. Series of such cells may extend back almost
if not quite to the germination of the spore from which
the mycelium arose.
A fusion of gametes morphologically equivalent to
those of other alge and fungi seems to have quite disap-
peared from the group so far as known at present, though
it is to be remembered that comparatively few forms
have been investigated as to the early stages of the for-
mation of the carpophore. It seems probable that the
endokarygamy in the basidium may have functionally
replaced an older fusion of differentiated sex cells.
We have then on the present evidence a large group
(over 9,000 species, according to Saccardo) of sapro-
phytic and parasitic organisms in which normal sexual
reproduction has been replaced by the fusion of nuclei
of probably separate descent through a long series of
cells, but which are contained at each stage within the
limits of a single cell body.
The most thoroughly worked out modification of sexual
reproduction in the fungi is the fusion of uninucleated
gametes producing binucleated series of cells in which
nuclear fusion follows only at a much later period. Such
538 THE AMERICAN NATURALIST [ Vou. XLIV
fusions seem probably to be present in all rusts which
have an æcidium or primary uredo and may occur in two
forms involving in the one case merely the migration of a
nucleus into a so-called fertile cell which then develops
into the chain of excidiospores, while in the other case
there may be a complete cytoplasmic union of equivalent
cells the so formed binucleated fusion cell then develop-
ing into a row of ecidiospores or a series of primary
uredospores.
Dangeard and Sappin Trouffy discovered that the
binucleated cells in the rusts originate with the ecidium,
but the real significance of the binucleated condition and
the method of its origin first became clear with the work
of Blackman, Christman and Olive.
It is quite probable, as Blackman maintains, that these
fusing cells in the ecidium of the rusts have been much
modified from the ancestral conditions of the sex cells of
the group, so that their fusion is to be properly charac-
terized as a vegetative fertilization. Still there can be no
question that functionally these are sexual unions, and we
can hardly imagine anything more illuminating as to the
relations of the male and female pronuclei in the cells
produced by fusion and hence containing the double
chromosome number. There can be no question here
that the male and female chromosomes maintain their
independence throughout the entire sporophytic life cycle
and that nuclear fusion and synapsis are two closely as-
sociated phases of that more intimate union of the chro-
mosomes which the behavior of hybrids suggests must
occur at the close of the sporophyte. Such a series of
binucleated cells is unknown among animals but the tend-
ency to persistent independence shown by the pronuclei
in the embryonic development of Cyclops shows that
there is every reason for believing that here and prob-
ably in all nuclei with 2n chromosomes the hereditary
idioplasms from the male and female parents maintain
quite the same physical independence throughout the
sporophyte as is so convincingly shown in the rusts.
No. 525] SEXUAL REPRODUCTION IN FUNGI 539
The phenomena of conjugate division also indicate very
clearly how the mechanism of karyokinesis, including
centrosomes, asters and spindles, may be partly or wholly
combined in a single system without necessitating a sim-
ilar union of the idioplasmiec units.
One of the most important points in this sexual process
in the rusts is that the nuclei do finally fuse in the teleu-
tospore. One might suppose that since the nuclei can
function as physically independent units through the
whole life of the sporophyte with its manifold vegetative
and reproductive phases, a reduction division might be
accomplished by the mere insertion of a wall between the
conjugate nuclei. This may be what occurs in Endo-
phyllum according to Maire. Still the fact that the
nuclei fuse before the heterotypie division in practically
all other rusts is certainly strongly suggestive that
synapsis and its accompanying phases represent a stage
of mutual influence if not of interchange of physical ma-
terial between the chromosomes much more intimate than
any which has preceded it in the life of the sporophyte.
On the other hand, it is plain that the nuclear fusion
is unnecessary so far as the sporophyte itself is con-
cerned. The sporophyte ‘of the rusts, as in other plants,
is the distinctively dominant and progressive phase in
the life cycle of the fungus. The uredo mycelium and the
rapid succession of crops of uredospores with all their
adaptations for rapid spread and virulent development
are a parallel in every respect to the sporophyte in every
type of plant in which it is found from the ferns to the
seed plants. It is plain then that the vigor and adapta-
bility of the sporophyte are not dependent upon the com-
bination of the sets of parental chromosomes in a single
nucleus. The same results are possible with two more or
less independent nuclei in the cell, each containing’ the
chromosomes from one parent.
For the ascomycetes Dangeard extended Wager’s ob-
servation of endokaryogamy in the basidium by the dis-
covery of a nuclear fusion in the ascus similar to that
540 THE AMERICAN NATURALIST [Vou XLIV
in the basidium and teleutospore. Dangeard pronounced
these nuclei which fuse in the aseus the morphological
equivalents of the gametes of other fungi and alge and
the resulting ascus a fertilized egg; a view in which he
has not been followed by other students of the group.
It seems probable, however, that this fusion functionally
may have the value in greater or less degree of a sexual
fusion, and that in cases in which the normal union of
gametes has disappeared this endokaryogamy may be a
substitute for it.
The most puzzling feature of the sexual reproduction
in the ascomycetes and that about whose existence, I may
add, there is least agreement, lies in the fact that in the
course of a single life cycle we have two nuclear fusions.
At the origin of the ascocarp we find the formation and
fusion of normally developed sexual cells and nuclei and
in the young ascus a fusion of included nuclei. There is
practically no dispute at present that the gametes formed
at the origin of the ascocarp represent the original and
normal sex organs of the fungus and for Pyronema the
fusion between the antheridium and trichogyne is uni-
versally admitted.
My own studies have convinced me that in the mildews
and Pyronema at least we have a normal conjugation of
differentiated gametes at the origin of the ascocarp and
an endokaryogamy in the ascus.
Blackman and Fraser confirm the existence of the two
fusions in Spherotheca and Blackman and Fraser (1906,
Humaria granulata), Fraser and Chambers (1907,
Aspergillus Herbariorum), Welsford (1907, Ascobolus),
Fraser (1908, Humaria rutilans), Cutting (1909, Asco-
phanus) and Dale (1909, Aspergillus repens) describe
the occurrence of two endokaryogamies in a single life
cycle,
As already noted, Claussen in a recent preliminary
paper attempts to resolve this diffculty in Pyronema by
claiming that while there is a normal cell fusion at the
origin of the ascocarp the nuclei of the gametes do not
No. 525] SEXUAL REPRODUCTION IN FUNGI 541
fuse, but are paired and divide by conjugate division in
the ascogenous hyphe, fusing only after they reach the
young ascus. This is a direct transference to the ascomy-
cetes of the conditions described by Blackman and Christ-
man for the rusts, and it is certainly an obvious and easy
suggestion. It was made in a letter to the writer by Raci-
borski in 1895 and later published by him.* In my opin-
ion, as noted above, judging from the size of the nuclei
in Claussen’s figures of the young ascogenous hyphe, the
nuclear fusion has already occurred at this stage.
It is evident that such profound changes as have led
to the wide-spread occurrence of endokaryogamy among
so many and such diverse groups of the fungi can hardly
have come about suddenly. Even on the mutation theory
it would hardly be supposed that in the rasts, for ex-
ample, the disappearance of function in the spermatia,
the new fusion in the ecidium, the long series of conju-
gate divisions in the destructive uredo stage of the
fungus and the endokaryogamy in the teleutospore
should all have appeared by a single step simultaneously.
There is a degree of correlation in all these changes with-
out doubt, but they must fairly be assumed to have
worked themselves out gradually in connection with the
development of the complicated life history with heterce-
cism and the numerous spore forms which characterize
the group.
It is evident that at present the fusion of nuclei in the
teleutospore is simply the delayed union of the gametic
nuclei that came together in the cell fusion at the base
of the row of ecidiospores. In my opinion, however, as I
have argued at length elsewhere, this fusion in the spore
mother-cell originated as a purely vegetative union as-
sociated in the ascus and basidium with the development
of the relatively gigantic size of these cells and the main-
tenance of the nucleo-cytoplasmie relation, the factors
involved being the abundance of nutritive material con-
centrated in the ascus and basidium as sporebearing or-
2 Flora, 1896, p. 132.
542 THE AMERICAN NATURALIST [Vou. XLIV
gans and their function as spore mother-cells which are
to undergo reduction divisions and close the sporophyte
generation.
From this standpoint it is to be remembered that we
have considerable evidence that in the rusts with abbre-
viated life cycles the binucleated condition and con-
jugate division extend back from the endokaryogamy to
more or less vague and uncertain points in the life cycle
of the sporophyte. For example, in the short-cycled rusts
with only teleutospores Blackman, Maire and Olive find
that the binucleated condition extends back from the
teleutospore to some undetermined point in the mycelium
from which the teleutospore sorus arises. As already
noted, it is certain that in various basidiomycetes the
binucleated condition extends back through the carpo-
phore to some not sharply marked stage in the mycelium.
Similar conditions may be present in the smuts.
In Pyronema I have found that the paired nuclei in the
young ascus arise by simultaneous division of two mother
nuclei in the tip of the ascogenous hypha from which an
ascus is to arise and that the spindles are so placed that
the two nuclei which are cut off in the young ascus and
subsequently fuse are not sister nuclei. This final
nuclear division is similar to the conjugate nuclear divi-
sions in the rusts. Recently Guilliermond and Maire
have described cases among certain of the larger dis-
comycetes in which the ascogenous hyphe were found to
consist of binucleated cells for some distance below the
young ascus, and suggest that these are comparable to
the binucleated series of cells in the rusts. In the major-
_ ity of cases so far described the ascogenous hyphe are
multinucleated as in Pyronema and Ascobolus. In the
mildews the cells of the ascogon below the ascus are uni-
nucleated and it does not appear that the nuclei which
fuse in the ascus come from any such distinct lines of
nuclear descent as do those which fuse in the teleutospore
of the rusts.
The binucleated condition may be working backward
No. 525] SEXUAL REPRODUCTION IN FUNGI 543
from the endokaryogamy in the ascus in the forms noted
by Guilliiermond and Maire, and further we have no cases
as yet in which the binucleated condition originating in
a cell conjugation without nuclear fusion is working
forward into the sporophyte. In the full-cycled rusts the
binucleated condition and conjugate division extend from
the gametic union to the reduction stage in the spore
mother-cell. This is manifestly a condition of equilibrium
comparable to the stable conditions present in most
forms with definitely limited alternation of generations.
In Pyronema in case Claussen’s preliminary contentions
should turn out to be true the same condition would be
presented. We have nowhere evidence that the binu-
cleated condition and conjugate division originated in
gametic fusions and worked gradually forward through
the sporophyte.
As perhaps the most striking evidence that the sapro-
phytic habit has not led to the disappearance of sexual-
ity we have the recent evidence as to the occurrence of
sexual fusions in the yeasts. It is probably too early to
speak with definiteness as to nuclear phenomena in these
minute cells. Still there can be no question that in Zygo-
saccharomyces we have normal conjugation of gametes
followed by two divisions and spore formation quite
probably representing a reduction stage. In Saccharomy-
ces Ludwigii just as clearly a double division period and
endospore formation is followed by conjugation. This
transposition of the sexual stage may be secondarily de-
veloped as Guilliermond believes, or may indicate the
polyphyletic nature of the yeast group. There can at
least be no question that sexuality either in a primitive
or modified form has been maintained in this otherwise
highly specialized saprophytic group.
Our knowledge of the conditions in the smuts as the
result of the work of Dangeard, myself, Federley and
Lutman, in a paper now in press, indicates that in this
group also two fusions may occur in a single life cycle
but under conditions which make the relations of the two
544 THE AMERICAN NATURALIST (Vor. XLIV
to each other and to the original sexual reproduction of
the group much clearer. In the smuts we have an endo-
karyogamy in the smut spore. In Entyloma the myce-
lium from which the spore arises is binucleated at least
in the later stages of its development. In Ustilago the
mycelial cells are multinucleated and there is less evi-
dence for the separate ancestry of the nuclei in the smut
spore.
The conjugations of the conidia regarded by DeBary
as sexual unions represent the only normal conjugation
of gametes in the life cycle, but they are plainly only of
sporadice occurrence. Certainly they are not necessary to
the completion of the normal development of the smut
and they may probably be assumed to be in process of
disappearance. The behavior of the nuclei in these
fusing conidia favors this view. Federley finds them
fusing in normal fashion in the smut of salsify. Lutman
finds also that the nuclei may fuse in the conjugation of
the promycelial cells of the oat smut. Dangeard finds
they do not fuse in the conidia of Tilletia and according
to my own observation the same is true in the conjugation
of the conidia of the anther smut, though here many of
the ordinary effects of sexual fusion appear in the con-
jugated pairs of conidia.
Lutman shows that infection and the normal develop-
ment of oat smut may occur without any such fusions,
and that hence the later nuclear fusion in the smut spore |
can not possibly be a delayed fusion of nuclei which came
together in an earlier normal cell fusion of gametes.
The endokaryogamy in the smut spore appears here as a
distinct process which has originated independently of
the normal sexual fusion, though it may have secondarily
developed sexual significance with the development of
conjugate division in the mycelial cells from which the
smut spores arise, and have thus made possible the en-
tire disappearance of the original normal sexual repro-
duction.
From this standpoint we are justified still further in
No. 525] SEXUAL REPRODUCTION IN FUNGI 545
the assumption that the appearance of binucleated cells
and possibly conjugate division in the ascogenous cells of
the discomycetes mentioned above indicate not the per-
sistence of unfused but paired gametic nuclei, but a work-
ing back of conjugate division from the spore mother cell
into the tissues of the sporophyte, thus giving gradually
to the endokaryogamy in the ascus more and more of a
sexual significance.
The evidence has accumulated in many lines that in
several groups of the fungi the sexual process is fol-
lowed by a longer or shorter period of development with
cells containing a double chromosome number. Evi-
dence from a direct counting of the chromosomes before
and after fusion is lacking, owing to the small size of
the nuclei, still there can be no reasonable doubt that the
regularly binucleated cells of the rusts which form an
unbroken series from the ecidium to the teleutospore
contain twice the number of chromosomes present in
the uninucleated mycelial cells from which the æcidium
-arises. As already noted, the conditions in the rusts are
especially favorable for demonstrating that the sexual
fusion inaugurates a period of development with cells
containing 2n chromosomes and that this sporophytic
stage tends to predominate in the life eyele both as to
length and complexity.
It is quite evident also in advance of a knowledge of
the complete cytological data that the double division
involved in forming the promycelial cells is to be con-
sidered as a reduction period.
In the smuts and Basidiomycetes the limits of the
gametophyte and sporophyte are not so definitely marked
as in the rusts, but the binucleated phase is certainly to
be regarded as sporophytic however it may be inaugu-
rated. In the Ascomycetes the morphological relations
` of the mycelium and ascocarp have long been regarded
as showing a parallelism with the conditions in liver-
worts and mosses. The fact of a triple division in the
ascus in contrast with the elsewhere universally present
546 THE AMERICAN NATURALIST [ Vou. XLIV
double division of spore mother cells has been regarded
as opposed to the interpretation of the ascus as a spore
mother cell. However, as I have pointed out, this triple
division replacing ordinary double division is to be re-
garded as correlated with two nuclear fusions preced-
ing it.
Miss Fraser has brought further interesting cytolog-
ical evidence that the third division in the ascus is a
reduction division which she characterizes as a brachy-
meiosis. The universality of the triple nuclear di-
vision in the ascus even in cases where less than eight
spores are formed is certainly to be regarded as a fact
of the first importance and comparable to the univer-
sality with which a double division occurs in other spore
mother cells. The most striking of the peculiarities as
to cell and nuclear fusions in the fungi may be summar-
ized as follows:
1. The fusion of multinucleated gametes.
2. The male element may be a mass of gonoplasm
rather than a definitely bounded cell.
3. Endokaryogamy, the fusion of nuclei not brought
together by cell fusion but of more or less independent
ancestry.
4. The fusion of gametes without the fusion of their
nuclei; the latter reproducing by conjugate division for
long series of cell generations and finally fusing just
before the reduction division.
5. Fertilization by nuclear migration from a vegeta-
tive cell to an egg or fertile cell.
Two successive fusions in the same life cycle, a
normal conjugation of gametes and later endokaryo-
gamy.
THE POSE OF SAUROPODOUS DINOSAURS!
DR. W. D. MATTHEW
AMERICAN MUSEUM OF NATURAL HISTORY
Tarse four articles discuss a question of considerable
general interest. Did the huge Sauropodous dinosaurs,
Diplodocus, Brontosaurus and their allies, walk like ele-
phants, or crawl like crocodiles?) The skeletons and casts
in the larger museums of America and Europe have all
been mounted straight limbed, with the body well clear of
the ground. But the evidence for giving them this pose,
so different from that of the generality of reptiles,
although well known to those who are responsible for it,
has not until recently been published. Hence it is not
surprising that these reconstructions have been criticized
more or less seriously, especially in Germany, and that
two writers of high scientific standing—Dr. Tornier in
Berlin, and Dr. Hay in Washington—have contended that
these animals could not have walked upright, but must
have dragged the belly on the ground as crocodiles and
lizards normally do. Both writers have attempted and
discussed at length the re-articulation of the skeleton in
the erocodilian pose.
Dr. Tornier’s argument is, briefly, that reptiles crawl
Rekonstruktion des Diplodocus,’’ von O. Abel, Abh. k. k. Zoöl.-
Bot. Gesellschaft in Wien, Vol. V., 1909-10, pp. 1-60 of separata, three
plates and text figures; March 24, 1910
‘t Review of some Recent Criticisms of the Restorations of Sauropod
Dinosaurs Existing in the Museums of the United States, with Special Ref-
erence to that of Diplodocus Caktsopion in the Carnegie Museum,’’ by Dr.
W. J. Holland, AMERICAN NATURALIST, 1910, Vol. XLIV., pp. 259-283, plate
I. and text figures, May, 1910.
‘‘On the Manner of Locomotion of the Dinosaurs, Especially Diplodocus,
with Remarks on the Origin of the Birds,’’ by Oliver P. Hay, Proc. Wash-
ington Acad. Sci., 1910, Vol. XII., pp. 1-25, pl. 1, text figs. 1-7, February
15, 1910
‘Wie war der Diplodocus carnegii wirklich gebaut?’’ von Gustav
Tornier, Sitz.-ber. Gesell. Naturf. Freunde zu Berlin, 1909, pp. 193-209,
ps. II. and 6 text figures.
547
548 THE AMERICAN NATURALIST [ Vou. XLIV
while mammals walk; that Diplodocus is a reptile and
resembles the lizards and crocodiles far more closely than
it does any mammals in the details of construction of the
shoulder- and hip-girdles, limbs and feet. Therefore, it
should be posed like one of the larger lizards, except for
the long neck, which he compares to the long-necked birds
and poses in accordance. <A sketch restoration and a
number of diagrammatic drawings illustrate his views.
The subject appears, frankly, to be somewhat outside the
range of his studies, and lie comparisons are not broad
or thorough enough to be at all convincing.
His criticisms are very effectively and completely
answered by Dr. Abel and Dr. Holland. These authors
point out that while the dinosaurs were reptiles and as
such their bones were constructed upon the reptilian plan,
yet they form a group apart, differing from other reptiles
and in many respects resembling the struthious birds;
that these resemblances, especially as regards the con-
struction of pelvis and hind limbs, leave no reasonable
doubt that the typical dinosaurs walked pretty much as
do the great ground birds; that the limbs of Diplodocus
and its allies differ from the normal dinosaur type in a
marked superficial and adaptive resemblance to the ele-
phant, indicating a quadrupedal “‘ rectigrade ’’ mode of
motion; that the skeleton articulates satisfactorily in this
pose and that the attempt to articulate it in the pose of a
crocodile or lizard involves either a demonstrably false
interpretation of parts, or a disarticulation of the joints
which proves such a position to be highly abnormal if
not utterly impossible for the creature to assume.
Dr. Hay’s contributions to the discussion—the article
cited and an earlier one in the AMERICAN NATURALIST—
are worthy of more careful consideration. Hay is a high
authority on fossil vertebrata, especially upon Chelonia
and fishes, and has recently devoted considerable study to
the dinosaurs. He recognizes the fact that the dinosaurs,
while pertaining to the class Reptilia, form a group apart,
with many analogies to the birds; that many dinosaurs
oad walk with the > clear of the ground, and that many
No. 525] THE SAUROPODOUS DINOSAURS 549
lizards walk or run in this way at times. He does not
deny that even the Sauropoda may have done so at times,
but regards them as too massive and heavy for this to
have been their normal mode of progress. But his chief
protest is against the placing of the knee and elbow joints
in sagittal planes (i. e., bending parallel with the middle
line of the body) as in mammals, instead of bending out-
ward as in all modern reptiles. In certain points of his
argument he makes out a convincing case in the re-
viewer’s opinion; other points may be satisfactorily
answered.
Dr. Hay misstates the supposed significance of the
peculiar type of femur seen in Diplodocus. He observes:
If the mammal-like gait of Diplodocus be insisted upon on the
ground of straightness of the femur, it may be pointed out .. . that
the femora of Sphenodon and of lizards, animals that creep, are straight.
If it be contended that it is in the heavy-bodied animals that a straight
femur is correlated with a lifting of the body from the ground durin
locomotion, it may be permitted to recall that the femora of Allosaurus
and Tyrannosaurus, great carnivorous dinosaurs, are distinetly bent.
The femora of Trachodon are straight, while those of Camptosaurus
and Laosaurus are curved. Curvature of the femur seems therefore to
have no relation to size of body or erectness of pose.
But no one, so far as the reviewer knows, has asserted
that the straightness of the shaft of the femur of Diplo-
docus, considered alone, proved that the animal walked
like a mammal. For among mammals there are both
straight and curved femora, and a wide variety of gaits.
The argument that Dr. Hay presumably has in mind
is this: That in the elephants and several other types of
gigantic mammals the femur is relatively long, straight-
shafted, with its articulations terminal rather than lat-
eral, the feet short, rounded, heavily padded and capable
of but limited motion, the whole limb being pillar-like and
normally held straight under the body. All gigantic
mammals show some degree of approach towards this
type of limb; and in the Sauropoda the resemblance in
form and proportions is very marked. The same type is
seen in Coryphodon, Uintatherium, Titanotherium,
Arsinoitherium, Pyrotherium, Astrapotherium, Dipro-
550 THE AMERICAN NATURALIST [ Vou. XLIV
todon, gigantic mammals of widely diverse stocks, in
Stegosaurus and Triceratops among the dinosaurs, and
an approach towards it in various other groups. The
modern horses, rhinoceroses, cattle and other large ani-
mals, and most of the very large extinct mammals show
a distinct approach toward these proportions as com-
pared with their smaller and more agile ancestors; so too
do the gigantic Trachodon and Tyrannosaurus as com-
pared with their smaller and more agile ancestors or rel-
atives, Laosaurus, Camptosaurus, and Allosaurus.
On the other hand, a glance at a lizard femur shows
that the straight shaft is associated here with a wholly
different position of the proximal and distal articulations
and of the trochanters by which the limb is moved. The
distal articulations for the tibia and fibula are on the
back of the femur, not on its end; the great trochanter
for the hip muscles projects outwards from the shaft
instead of upwards in line with it; the feet are long and
the toes relatively elongate; there is very little padding.
The shaft of the femur is nearly straight in the aquatic
turtles and the articulation for the lower limb is quite
distal in position; but the trochanter projects upward,
the limb is carried outward from the body and more or
less straight. In the land turtles and in the crocodiles
the femur has a strongly curved shaft, bent downward at
the distal end, the limb still projecting outward from the
body but flexed sharply downward at the knee. Here
then are two distinct methods by which a swimming limb
may be converted into a crawling limb.
. The straight-shafted femur does not per se prove that
Diplodocus walked in any of the various ways that mam-
mals walk. But taken in connection with the numerous
other adaptive resemblances in form and proportions of
the bones of the hind limb, feet and pelvis, to the ele-
phants and other gigantic mammals and reptiles cited,
it does afford a very strong argument for asserting that
Diplodocus walked like an elephant as to its hind limbs.
Dr. Hay’s next point appears to be a strong one. He
observes that if we compare the femora of such dinosaurs
No. 525] THE SAUROPODOUS DINOSAURS 551
as Allosaurus, Tyrannosaurus, Trachodon or Campto-
saurus, admittedly erect-walking bipedal forms, with the
femora of the Sauropoda, we find a great difference in the
quality of the bone and the finish of the articulations.
The shaft of the former appears to be more elaborately modelled, and
to consist of finer and harder bone; all the articular surfaces are smooth
and they carry the conviction that the original surfaces, barring a thin
layer of cartilage, are preserved; there is a definite head, separated
from the shaft by a distinct neck, and nearly filling the acetabulum;
and there is a definitely formed trochanter major. In the Sauropoda,
on the contrary, the shaft seems to be composed of coarser bone; the
articular surfaces are rough and show that they were covered by a
thick layer of cartilage; the head merges imperceptibly into the sup-
posed great trochanter and into the shaft; [it would be more accurate
to state that the great trochanter is not a separate process but a rugose
area marginal to the head of the femur] and the head lacks much of
filling the acetabulum. In its [sic] low stage of differentiation the
femora of the sauropods resemble greatly those of the crocodiles and
are hardly above those of the lizards.
It is not clear what lizards Dr. Hay had here in mind.
The larger land lizards have a much more ‘‘ differenti-
ated ’’? femur. Even in the crocodiles the resemblance is
not‘very close. But a much closer and more striking re-
semblance in the characters cited may be found if we
compare the femora of large aquatic reptiles, ichthyo-
saurs, mosasaurs or plesiosaurs, or large aquatic mam-
mals such as the Cetacea, with the femora of the Sauro-
poda. The reviewer would agree entirely with Dr. Hay
that the lack of differentiation and finish in the limb bones
of Sauropoda is a strong argument that they were not
adapted to the habitual support of the whole weight of
the body. But the evidence cited accords exactly with the
theory of Owen and Cope that they were wading animals,
and the limbs were designed for the support of the body
in the water, with most of its weight buoyed up thereby.
Dr. Hay believes that the position of the great trochan-
ter in the Sauropoda was well down on the shaft, as it is
in the Triassic Theropoda; but he fails to give any good
reason for rejecting Osborn’s view that the very clearly
marked rugosity around the proximal-external angle of
the head is the area of attachment of the gluteal muscles.
552 THE AMERICAN NATURALIST [ Vou. XLIV
The character of this rugosity is certainly that of an
attachment for powerful muscles; its position is substan-
tially that of the distinct process in the larger bipedal
dinosaurs; while the surface where Dr. Hay would locate
the attachment is a surface of smooth bone. On the other
hand, the view of Marsh and Hatcher, apparently shared
by Holland, that the entire proximal-external angle, in-
cluding part of the rugose surface of the proximal end,
similar in character to the rest of the anatomical head or
articulating surface, is the great trochanter, appears to
be indefensible, and Dr. Hay’s arguments conclusive as
against it. This view seems to have been founded on the
analogy with the proboscidean femur, carried further
than the facts warrant. But Dr. Hay’s conclusion that
the femur of the Sauropoda represents a very early
stage in progressive adaptation of the limb from the
primitive swimming to the walking type, is not war-
ranted if Osborn’s view as to the position of the tro-
chanter be correct, for as Hay rightly observes, in the
progressive stages of adaptation to upright carriage
this attachment moves up towards the head of the bone.
But the only semblance of argument that Dr. Hay offers
against this view seems to be the assumption that Diplo-
docus was more primitive than its Triassic predecessors.
The truth seems to be that the Sauropoda were highly
specialized as regards the adaptations for upright walk-
ing, but degenerate as regards the adaptations for bear-
ing great weight on the limbs.
As to the aquatic habitat of the Sauropoda, Dr. Hay’s
statement of the evidence can hardly be regarded as a
fair one, although he seems to be of the opinion that the
larger forms, at any rate, were secondarily aquatic.
The ability of any large animal to walk about thus submerged must
depend on its having a massive skeleton, as have the hippopotamus and
the manatee. In Diplodocus, on the contrary, almost every conceivable
device has been used to reduce the weight of the skeleton. The great
vertebre contain large and small internal cavities, while externally the
processes are carved into thin plates and buttresses, and the centra are
deeply excavated on each side. Moreover, as has been shown by
_ Hatcher, the limb bones are hollow. It would seem to have been hardly
No. 525] THE SAUROPODOUS DINOSAURS 553
more possible for Diplodocus to walk about immersed in water than it
would be for a man to do the same.
In a brief description of the Brontosaurus skeleton?
which Dr. Hay consistently ignores, although he can
hardly fail to be acquainted with it, the reviewer pointed
out that there was a very marked difference in the mas-
siveness of the upper and lower parts of the skeleton in
the Sauropoda. All the bones above a line passing
through the acetabulum and glenoid cavity of the scapula
are very lightly constructed, and thus far Dr. Hay’s
statement is correct. All the bones below this line are,
on the other hand, very massive, and solid or nearly so.
So far as the reviewer can judge from comparison of a
large series of bones, they are quite as dense and massive
as the corresponding bones in the hippopotamus; and
they certainly are not hollow in the sense that the bones
of Allosaurus are hollow. All of them are cancellous
towards the center, and in the femur there is an open
cavity of proportionately small size in the shaft. But
they are certainly far more dense than in the elephant,
and wholly lack the devices for lightening the weight that
are so conspicuous in the skull, cervical and dorsal ver-
tebre, the first few caudals, the ilium and the proximal
ends of the ribs. The median and distal caudals, the
ischia, pubes and limbs, the shoulder-girdle, except for
the blade of the scapula, and especially the feet, must be
wholly excepted from Dr. Hay’s statement in regard to
the lightening of the skeleton; they are certainly unusu-
ally massive in form; and while the precise degree of den-
sity of the petrified bone is not very easily compared with
modern bone, yet in the reviewer’s opinion they compare
most nearly with the bones of aquatic animals, such as
plesiosaurs and mosasaurs among the reptiles, cetaceans,
pinnipeds, sirenians and hippopotami among the mam-
mals, and are materially exceeded in density only by the
sirenians.
Dr. Hay’s observations in regard to the pose of bipedal
dinosaurs form an interesting corollary to his views in
2 Amer. Mus. Guide Leaflet No. —, 1905.
554 THE AMERICAN NATURALIST [Vou. XLIV
regard to the Sauropoda. For although admitting that
they were in general bipedal and walked with the body
clear of the ground, he finds himself compelled, in the
logical development of his theories, to assign them a
widely straddling walk. This compels him to explain the
observed tracks of Iguanodon, which are not straddling,
as being an unusual mode of progression associated with
slow walking, but that if the animal had been running it
would have had a wider trackway. So far as the re-
viewer’s observations extend, the faster an animal is
walking or running the more it is inclined to plant the
feet close to the median line of its trackway, and the less
likely to waddle—this is assuredly true of our own gait,
and probably holds good with any bipedal animal. The
stronger evidence derived from the numberless tracks of
the Connecticut Valley Triassic, Dr. Hay would explain
by supposing that these tracks were made, not by dino-
saurs which we know existed, but by birds of whose ex-
istence at that time we have no evidence.
But Lull has shown that not only do many of these
tracks correspond precisely and in detail with the recon-
structed hind feet of carnivorous dinosaurs, but the oc-
casional impressions of the fore feet, the pubes and the
tail, correspond equally well. A disputed hypothesis in
regard to the amount of straddling in their gait is hardly
sufficient ground to question the accepted view that these
tracks were made by dinosaurs.
It is indeed quite reasonable to suppose that ancestors
of the birds, more or less closely related to the dinosaurs,
were living during the Triassic. But the extreme rarity
of bird remains during the whole Mesozoic, and the fact
that, with the exception of Archeopteryx, the better
known forms are highly specialized aberrant types, gives
ground for supposing that the normal habitat of Mesozoic
birds was such that their remains were not buried in the
areas of sedimentation. They were presumably confined
to the higher and drier uplands, remote from the river-
deltas and coastal swamps which were the normal habi-
tat of the heavy and bulky dinosaurs, and which the
No.525] © THE SAUROPODOUS DINOSAURS 555
lighter and smaller dinosaurs of the upland visited to a
greater or less degree.
r. Hay makes considerable use in his discussion of
Marsh’s restoration of Anchisaurus, as in this reconstruc-
tion the limbs appear relatively shorter and the pro-
portions more lizard-like than in most Theropoda. But
while this is true to some extent of Anchisaurus and ap-
parently of most Triassic Theropoda, it is exaggerated
in Marsh’s reconstruction by insertion of several addi-
tional dorsal vertebrae which are probably not warranted.*
The restoration is a composite from two or three partial
skeletons ; the number of vertebre is really uncertain. If
the body be shortened to the proportions of the more
completely known dinosaurs, there is less difficulty in
supposing the animal to have been habitually bipedal, and
bird-like in gait. The general contention that the dino-
saurs evolved from a crawling lizard-like gait to a bipedal
bird-like gait without passing through a quadrupedal
walking mammal-like gait appears probable enough. But
the Sauropoda seem to be most easily explained by the
hypothesis that they acquired secondarily a quadrupedal
elephantine gait, that they were at first more or less
amphibious and finally exclusively aquatic waders.
Whether we state, as does von Huene, that the Sauro-
poda are derived from Theropoda, or, as Dr. Hay will
have it, that the Theropoda are derived from Sauropoda
seems to be largely a question of terms and definitions.
Both are derivable from a common ancestral group, but
the Sauropoda have specialized fully as much in one
direction as the Theropoda in another. In fact, in the
present writer’s opinion, the Sauropoda are decidedly
more specialized, although their specialization is in part
degenerative and a re-adaptation to the aquatic environ-
ment of the remote ancestors of the Reptilia.
3 Marsh has inserted additional dorsal vertebre in most of his dinosaur
restorations, as may be seen by EEEREN with the more complete AEA
which have since been mounted and described in several American museu
There are three too many in bendibes (Riggs), five too many in Pisa
tosaurus and six too many in Triceratops (Gilmore) and so on probably
throughout. His general concept of the analogy of the group seems to have
been too much lizard-like and not enough bird-like.
556 THE AMERICAN NATURALIST [Vou. XLIV
Dr. Holland’s article is a brilliant, well-illustrated and
cruelly convincing polemic in support of the accepted
pose of the Diplodocus skeleton, but in the reviewer’s
opinion he does not at all do justice to the real weight of
some of the arguments advanced by Hay and Tornier,
especially the former. Serious exception might be taken
to the positiveness of some of his assumptions, as well as
to the ridicule of his opponents’ views.
Holland shows by aid of a series of photographs and
carefully finished drawings that the pose advocated by
Dr. Tornier could not have been assumed without an
entire dislocation of the important limb joints; that the
pelvis of the sauropods is like ‘‘ the pelves of the dino-
sauria in general, distinctly ornithic in type, not lacer-
tilian nor crocodilian,’’ that the body is deep, narrow and
short as in birds, while in the crawling reptiles it is broad
flattened and more elongated; that the scapula and fore-
limb differ in important features from those of crocodiles
and lizards, and the fore limb can not be articulated in a
crawling pose; that the long heavy tail affords no argu-
ment for a crawling posture; that the feet are digitigrade
and not plantigrade as asserted by Tornier; that the gen-
eral form and proportions of the limbs point to an ele-
phantine pose, and that the single known footprint of a
Jurassic Sauropod supports the same interpretation.
(It is worthy of note that Dr. Lull has carefully examined
this footprint and come to the conclusion that it was prob-
ably made under water rather than on land.) The whole
article is very readable and clearly written, and would
seem to close the case so far as the possibility of Tornier’s
reconstruction is concerned.
Dr. Abel’s contribution is a careful, thorough and fair-
minded consideration of the problem by a high authority
upon fossil vertebrates, who has devoted a great deal of
time and thought to paleontologic reconstructions. He
reviews the principles governing such work, the relation-
ships of Diplodocus and the data for the reconstruction,
the opinions that have been held in regard to the pose
ee and habits of the Sauropoda, and cites Tornier’s argu-
No. 525] THE SAUROPODOUS DINOSAURS 557
ments in some detail. He then gives a careful and critical
presentation of the evidence afforded by, the form and
relations of the different parts of the skeleton. He con-
cludes that the generally accepted poses, as shown in the
several skeletons of Sauropoda that have been mounted,
and in the published restorations by Marsh, Hatcher,
Holland and Osborn, are in the main correct, except that
the scapula should be somewhat more vertical, the elbow
directed more outward, and fore and hind foot completely
digitigrade. He finds no warrant for the radical changes
in pose recommended by Tornier and Hay. The evidence
can not well be condensed within the limits of a review.
The marked analogy to the elephants, especially in the
proportions and relations of both fore and hind feet, and
in the limb bones the relationship to the bipedal dino-
saurs, much closer than to the crawling reptiles, the
mechanical requirements for the support of a body of the
size and proportions of a Sauropod dinosaur, are the
chief criteria used to interpret the direct indications
from the bones of the Diplodocus skeleton.
Dr. Abel’s conclusions may be condensed from his sum-
mary as follows:
1. The animal did not crawl, but walked, with the body
well clear from the ground, the knee bending forward, the
elbow outward and backward, the feet digitigrade as in
the elephant. In a standing position the angle at the knee
was slight (15°), while the bend at the elbow was more
considerable (60°). The fore feet were longer and more
completely digitigrade than the hind feet; both fore and
hind feet were exaxonic, the weight of the body resting
chiefly on the outer digits, which were heavily padded,
with rudimentary toes, while the innermost toe of the
fore foot and the inner three toes of the hind foot bore
large blunt claws.
2. The body was deep and narrow, strongly arched
from front to back, the neck long and flexible, normally
carried forward, with the head continued in the same
direction.
3. There were twelve thoracic vertebrae, of which the
558 THE AMERICAN NATURALIST [ Vou. XLIV
first is unknown; and sixteen cervicals, of which the first
(pro-atlas) is unknown. The problematic bone identified
by Holland as clavicle, by Nopsea as os penis, by Tornier
as episternum, is the first rib.
Some of the points cited may be questioned or dis-
proved,! but the main contention, that the Sauropoda
were walking, not crawling animals appears to be abun-
dantly proved.
Nevertheless, there is a great deal yet to be said on the
pose and habitat of the Sauropoda, and there are certain
lines of evidence which none of the authors cited have
considered adequately.
In the first place, the nature and cause of the paral-
lelism between sauropod dinosaurs and elephants has not
been very clearly pointed out. The type of limb and foot
structure which they show in common was first clearly
defined, so far as the reviewer is aware, by the late Pro-
fessor Gaudry, under the name of ‘‘ rectigradism.’’ It
is a specialization directly associated with gigantic size,
the limb becoming straight and pillar-like, the foot short,
round, heavily padded, with toes reduced or vestigial.
The movements of the limb are chiefly at the upper joints,
the foot serving chiefly as pad or cushion to absorb the
shock in locomotion. This is very different from the
typical ‘‘ digitigradism ” of the dog or cat; it may be
observed with modifications, in large plantigrade and
unguligrade animals as well as in digitigrade forms, and
a progressive approach towards it may be observed in all
races of land vertebrates as they approach gigantic size.
The proximal segments of the limbs tend to become longer
and straighter, their articulations more terminal, the
distal segments shorter, their range of movement de-
creasing, the toes become much shortened and vestigial,
buried in an elastic pad, or, as in ungulates, with a broad
horny hoof, which absorbs shock less completely but gives
a firmer footing.
* The insertion of two additional dorsal vertebre is aars erroneous,
and with this falls to the ground the interpretation of the ‘‘clavicle’’ as a
rib. Positive evidence from other partially articulated skeletons is likewise
available, I believe, to determine the number of cervical vertebra.
No. 525] THE SAUROPODOUS DINOSAURS £59
Obviously a specialization of this kind will oceur only
in an animal which habitually rests its weight on the
limbs, and it is necessary with increased weight, because
the increase of weight varies as the mass (cube of the
linear dimensions) while the increase in strength varies
as the cross section (square of the linear dimensions).
This last cireumstance will very clearly set a limit to
the size that an animal may attain as a practical working
mechanism. And here we are brought to face an un-
answerable difficulty if we consider the Sauropoda as
land animals. How is it that with their less perfect rep-
tilian organization of limbs and feet they were able to
attain so much larger size than has since been attained
by the land mammals with their more perfected organiza-
tion. Throughout the Cenozoic we see race after race
of gigantic land mammals successively culminating and
disappearing, each a little larger than its predecessor,
each assuming the rectigrade limb as it approaches its
maximum size, the Proboscideans, the latest and largest
of all, and, so far as can be judged, the most perfect in
mechanical organization. But the Sauropoda, away back
in the Jurassic, far surpassed the largest elephants in
size; and yet their joints are rough, imperfect, cartilage
covered, their muscular attachments imperfectly differ-
entiated. If the elephant is the largest size that the per-
fected mammalian organization permits, how is it possi-
ble that the relatively imperfect dinosaur organization
could so far exceed it? And if it is not, why have none
of the numerous gigantic Tertiary mammals exceeded
this size?
If, indeed, we regard the Sauropoda as aquatic ani-
mals, adapted to wading, we solve this difficulty readily
enough, and find also an explanation for various pecul-
iarities in their construction which remain unexplained
if they are considered as land animals. A wading animal
has the greater part of its weight buoyed up by the water,
and might attain a much larger size without transcending
its mechanical limitations, just as the whales and some
true fishes attain a much larger size than any land animal.
560 THE AMERICAN NATURALIST [Vou. XLIV
A second point that does not seem to have been brought
out in the discussion is that the dinosaurs are distin-
gnished from other reptiles by the relatively large size
of the legs as compared with the body. In this respect
they have the proportions of mammals and birds. The
significance of this would seem obvious. A crocodile,
turtle or lizard crawls habitually, because his legs are not
large enough to carry the weight of his body. In dino-
saurs, as in mammals and birds, the legs are large enough
to carry the body comfortably clear of the ground and
presumably served that purpose.
The nearest approach to the dinosaur proportions is
seen in some of the lizards, and it is just among these
that we find a tendency to lift the body from the ground,
especially during running.
Another general consideration lies in the question of
the primary adaptation of the dinosaurs. Dr. Hay very
justly remarks that it is by no means necessary to sup-
pose that the bird-like (bipedal) dinosaurs had passed
through a mammal-like (quadrupedal) stage of evolution.
Indeed, if we regard the lizard as illustrating early stages
of a similar adaptation, the evidence would be just the
other way; the bipedal stage in dinosaurs came first, the
quadrupedal stage was a secondary adaptation. This is
generally admitted as regards the quadrupedal dinosaurs
of the Predentate group; the reviewer believes that it is
also true of the Sauropoda, although the indications of
former bipedalism are less apparent in this group. The
hypothesis would serve, however, to explain several odd
features in their construction—e. g., the combination of
everted elbow with straight knee—and would connect
them more definitely with the Theropoda of the Triassic,
to which they are structurally traceable, as von Huene
has demonstrated.
SHORTER ARTICLES AND DISCUSSION
EVOLUTION WITHOUT ISOLATION
Tus is the title of a brief but interesting article by O. F.
Cook, in the AMERICAN NATURALIST for November, 1908. My
response to the same has been delayed by the pressure of other
things.
I fully agree with Dr. Cook in his statement that ‘‘The choice
of words is worthy of careful consideration, but words should
not lead us away from the broader issue of biological facts.”’
We both maintain that there may be evolution without isola-
tion; but I do not see how he can reconcile the following state-
ments, found in the above mentioned article, with the facts of
nature. ‘‘The separation of a species into two or more parts
allows the parts to become different, but there is every reason to
believe that evolutionary changes of the same kind would take
place, if the species were not divided.” Again: ‘‘Isolation,
though making more species, impedes evolution.’’ Does he mean |
that if man and the anthropoid apes had remained one freely
intergenerating species, a higher degree of intelligence would
have been reached than has been attained by man under the con-
dition of isolation between him and the apes? Does he mean
that the progress of the mammals, as a whole, would have been
more rapid, if they had remained one constantly intergenerating
species? Does he mean that, in the case of mammals, “‘ changes
of the same kind,’’ as we now see, in size, in form, in instinets,
in power to live, some in the sea like the whales and the por-
poises, some on the land, some on the trees, some in hand-made
houses, would all have taken place, if we, the mammals, had re-
mained one species? Would these changes have come in succes-
sive generations, in one continuously changing kaleidoscope; or
would each successive generation have become increasingly com-
plex, till the mouse could produce, not only mice, but all other
mammalian forms, including the eat, the flying-squirrel and the
whale?
In many places in my volume on ‘‘Evolution,’’ published by
the Carnegie Institution, I speak of isolation and selection as
controlling factors, while growth, reproduction, heredity and
561
562 THE AMERICAN NATURALIST [ Vou. XLIV
variation are classed as fundamental conditions in evolution.
Some of these passages will be found on pages 29-34, 59-60,
79-80, 138. I also show that the forms of isolation and selec-
tion, that divide and guide the process of evolution, are often
determined by relations between sections of the species, and
may therefore be classed as autonomic. See pp. 138-39, 141-44
and 158. These autonomic forms of isolation and selection come
under what Dr. Cook defines as processes of evolution, that is
‘‘ processes of spontaneous change,’’ as does also the process of
reproduction with variation. If autonomic processes of isola-
tion and selection are forms of evolution, shall we claim that
natural selection, because it relates to the power of individuals
and groups to meet influences in the environment, has, there-
fore, nothing to do with evolution, except as it retards evolution ?
If the power to assimilate good and abundant food helps in the
process of evolution, may not the survival of those having this
power in the fullest measure help in the same process? How
then can Dr. Cook say, as on the second page of his article, that
isolation and selection neither cause evolution, nor help it along?
I can suppose that his answer might be, that, in as far as these
factors have influence, the changes produced cease to be spon-
taneous, and, therefore cease to be evolution, as he understands
evolution. But this explanation does not seem to be applicable
to eases of transformation arising under isolation and selection
caused by autonomic influences, for example by sexual and so-
cial instinets.
There are, it seems to me, many difficulties in the way of re-
garding the term evolution as applicable only to ‘‘spontaneous
processes of change,’’ unless we class all vital action, including
variation and the survival of the fittest, as spontaneous, in that
it arises from within, and its origin is life producing life from
itself, and never life springing out of the dead environment, or
out of widely different forms of life. And then we should have
to meet the objection that all life is dependent on external con-
ditions for its food, and, therefore, for continued existence, and
so no vital action is spontaneous in the sense that it is indepen-
dent of conditions in the environment.
Let us suppose that a little snail, clinging to a leaf is carried
by a bird, from the home of the species in a valley on this island
of Oahu, and dropped in an adjoining valley half a mile away,
where the conditions of soil, vegetation, rainfall and tempera-
No.525] SHORTER ARTICLES AND DISCUSSION 563
ture are the same as in the home valley. It finds a grove of the
same kind of trees as that from which it came, and from its young
arises a permanent colony. At the end of a few scores of years,
what do we find? It has blossomed out in a new group of varia-
tions not found in the original stock, and some of the original
characters have disappeared. Here is what seems to be ‘‘a
spontaneous process of change”; and we are about to call it a
genuine case of evolution, when Dr. Cook reminds us that, if
this change could not have taken place without isolation, it is
not spontaneous, and that it is really a case of the impeding of
evolution.
In the course of time another branch colony is formed, which
varies from the original stock in habits of feeding and seek-
ing of shelter from the sun. It gradually, but spontaneously,
takes to the shrubbery near the ground, and deserts the trees;
and so subjects itself to a new form of selection. The change is
greater than in the former case, and is undoubtedly due to
spontaneous variation, with survival of the fittest under new
conditions chosen for itself spontaneously; for the kind of
trees, on which the original stock lived, are found in abundance
all around. Shall we call the process a case of evolution, or
simply the checking of evolution through isolation and selec-
tion? I am inclined to define evolution so as to include the
processes of change in such cases as these.
In this same article we find statements giving still greater
limitation to what the author considers the real process of evo-
lution. In the last paragraph it is called, ‘‘The processes of
‘spontaneous, progressive change in species.’’ On the third page
also, we read: ‘‘ Divergence may be greater than evolution when
changes are not progressive, but sideways, or backwards.” If
the change in a species must be shown to be entirely spontaneous,
and also not sideways or backwards, but upward, before we can
venture to speak of it as an example of evolution, this word,
now so popular, will find itself badly ostracized. ‘‘Speciation’’
is introduced as a rival for part of the field; but I am not sure
that it will show itself better fitted than the term divergent evo-
lution. I am, however, willing that the fate of the two should
be left to the struggle for existence, and the success of the fittest,
which I regard as one of the controlling factors in the evolution
of language. The statement I am unwilling to accept is that
isolation and the survival of the fittest (that is species-forma-
564 THE AMERICAN NATURALIST [ Vou. XLIV
tion), have no connection with evolution except that they may
impede the process. If all organisms came from one original
intergenerating stock, deriving its food from the inorganic
world, and from the dead individuals of its own kind, how far
could evolution have progressed without any formation of sepa-
rate species? What would now become of the organic world if
isolation and selection ceased and all the separate species were
merged in one? When I say that there may be evolution with-
out isolation I mean without additional isolation. I do not mean
that the undoing of all the effects produced by vital forces
making isolation complete, though the different genera occupy
the same district, would be:an advance step in evolution. On
the contrary, I think that such an undoing would mean the
crumbling of the whole fabric of the organic world.
Is not racial evolution a:term that we can rightly and wisely
apply to all the processes of change in organisms affecting
characters that are subject to the laws of heredity and variation?
May it not be applied to all changes in races and species result-
ing, not only from the aetion and reaction of members of the
same species upon each other, but also from the action and re-
action between individuals or groups and their environments?
May not evolution be either divergent, convergent or parallel?
either progressive, or retrogressive? May it not take place with-
out any change in the environment, and in that sense be spon-
taneous; and may it not be due to vital action stimulated,
guided, and controlled by external conditions?
HONOLULU, HAWAII. JoHN T. GULICK.
RETROACTIVE SELECTION!
In his contribution to THE AMERICAN NATURALIST of July,
Professor Marshall makes some statements which I wish to cor-
rect. Among other things he says:
*** Retroactive Selection’’ is a term used by me to designate the modi-
fications of each selection by the selections which follow. Thus,. selection
No. 2 modifies selection No. 1 by eliminating part of the animals which
selection No. 1 retained as breeders. Selection No. 3 modifies selection No.
this in turn causes a second modification in selection No. 1 by a
more of those originally retained. In the same way, selection No. 4 m
fies selections y: 1, 2 and 3; selection No. 5 modifies selections Nos. i 2,
3 and 4; and so
A study of sae T selection is a study of the successive modifications
of eariy selections by the retroactive effect of later ones.
No.525] SHORTER ARTICLES AND DISCUSSION 565
Mr. Redfield would say that the effects of environment are inherited.
It would require too much space to explain how this misappre-
hension of my position became prevalent. It is sufficient for the
present purposes to say that it is a misapprehension, and that
I am not taking the ground that the effects of environment are
inherited—at least not in any sense in which a plain statement
to that effect would imply.
What I am interested in at the present time is learning what
explanation others would give of certain facts which I have dug
out of records. One of these facts relates to the ages of sires
in pedigrees of 2:10 trotters, or trotters in general, and as this
subject has already been opened it appears a fitting one to
continue.
After quoting what I had to say about sires appearing older
and older the further we go back in the best pedigrees, Professor
Marshall says:
The evident conclusion from this statement is that our best horses
come from an increasing popularity of younger sires.
The error in this statement is more in what it implies than in
what it actually says. Young sires are popular and have been
popular during the entire history of breeding the trotter. Many
very fast trotters have come from such sires, but a consideration
of those raises a collateral question which it is better to postpone
to a later date. What actually occurs in the breeding of trotters
may be described as follows:
Assume some thousands of animals belonging to the trotting
stock as it existed in this country, say seventy-five years ago.
Using conerete numbers for illustration, we will say that out
of these horses one thousand stallions are selected for breeding
purposes to produce the next generation. We will designate
these one thousand stallions as the first generation and the first
selection in a process of selection which we will follow through
several generations as it has actually been employed by the
breeders of trotters. These one thousand stallions were sons of
sires which were, on the average, 10.4 years old at the time the
sons were born. It may be added here that this 10.4 years
between generations in the male line is the approximate average
as it has existed at all times within the known history of the
trotter. A detailed investigation of the ‘‘ Trotting Register ’’
for different periods shows that at no time have ordinary breed-
ing operations varied from this except in the value of the decimal.
566 THE AMERICAN NATURALIST [ Vou. XLIV
The one thousand stallions of the first generation produce the
second, of which some ten thousand or more are stud colts. Out
of these a second selection of one thousand stallions is made for
breeding purposes to produce the third generation. The stal-
lions of this second selection are sons of sires averaging 10.4
years of age, and the selection is based principally upon the per-
formances of their sisters, their cousins and their aunts. Don’t
fail to note the fact that until very recent years, stallions were
rarely selected for breeding purposes because of their own per-
formances. Horse history is full of the assertions by breeders
that stallions intended for breeding should never be raced.
ow we come to the critical point to which close attention
should be given. The one thousand stallions of the second selec-
tion are not the sons of the full one thousand stallions of the
first selection—one son for each sire. On the contrary, some
sires in the first selection are represented by numerous sons in
the second selection, while other sires in the first selection are
not represented at all. In other words, about one-half of the
first selection of sires is cut out by the second selection. This
weeding out of the sires of the first selection is done largely
after the sires themselves are dead, and is based upon the per-
formances of animals other than the sires of either generation.
When we examine the sires of the first selection after the
weeding-out process involved in the second selection, we find
the sires eliminated by the second selection to have been prin-
cipally, though not wholly, sons of young sires; and that the
sires which are retained to breed on in the male line to the third
generation, are principally, though not wholly, sons of old sires.
The net result of cutting off part of the original selection by the
second selection is that the 500 left are sons of sires averaging
about 12.5 years of age. 2
In due course of time a third selection of one thousand stal-
lions is made from the third generation for the purpose of
producing the fourth, and they in turn are sons of sires averag-
ing 10.4 years of age. But all of the stallions of the second
selection are not represented in the third selection. In fact
about one half of them are cut off, with the result that the 500
which are left in the second selection, after making the third
selection, are sons of sires averaging 12.5 years. Now, when
the third selection cut off part of those originally in the second
selection it also cut off many lines of descent back to the first
No. 525] SHORTER ARTICLES. AND DISCUSSION 567
generation. The horses which were thus cut out of the first
selection by the third selection, occurring some thirty or more
years later, were more largely sons of young sires than sons of
old sires, with the net result that those left were sons of sires
averaging 13.5 years of age.
This is the process which has been going on from generation to
generation—each selection reducing the number of horses in ear-
lier generations which are left to breed on to later generations.
Chester proved some years ago that all known standard trotters
were descended in the male line from one or another of no more
than seventeen foundation horses. While these all stand as hav-
ing been progenitors of trotters, the majority of them represent
what are now extinct families, so that the trotters as now bred
come in the male line from only six or eight horses.
The process set forth explains how it comes about that, in
examining the pedigrees of any trotting stock, the further we
go back in those pedigrees the older the sires appear, but it does
not explain why a late selection cuts off young sires and pre-
serves old sires of earlier generations.
That is the supreme question I am asking biologists. I have
asked it in several forms before without getting a reply com-
mensurate with what I consider the importance of the question.
It is hoped that the present form, accompanied by the explana-
tion upon which the form is based, will bring forth a genuine
effort to explain the cause of these remarkable facts.
Casper L. REDFIELD.
THE LOGIC OF CHANCE IN PROBLEMS OF GENETICS
THe literature at present appearing dealing with problems
of genetics and evolution teems with uncertainty and inexact-
ness in the use and misuse of the word ‘‘chance.’’ Some definite
understanding of the significance of the concept as a legitimate
category of scientific reasoning seems desirable. At any men-
tion of the word chance, some listener is sure to rise in protest
with the old adage—‘‘There is no chance, it’s only your ignor-
ance.” The acceptance or the rejection of this bit of prophecy
depends on the ultimate postulate of the absolute uniformity of
nature. The truth of this postulate is a metaphysical question
with which the ordinary student of genetics is not coneerned.
He is reminded of the fact that Darwin and all after him have
568 THE AMERICAN NATURALIST [Vou. XLIV
used the word ‘‘chanee’’ in many ways and he demands a defi-
nition of the term which shall meet his usage without involving
metaphysical postulates.
The particular problem of genetics arises within a more or less
precise universe of discourse. Within it lie a broad range of
biological phenomena which the student of the problem is bound
to take into consideration. Without this definite universe of
discourse lie a still greater range of phenomena—chemieal, phys-
ical, geological, ete—which he is bound to neglect. His problem
ean not be made to encompass the whole universe, simply be-
eause the multiplicity of facts regarding the universe impede
rather than advance the progress of the understanding of his
particular problem. His universe of discourse must be precise
and relatively small to be serviceable. Within this limitable
universe of discourse the observer will discover certain regu-
larities. These will constitute for him the laws. Certain other
groups of phenomena will appear seemingly without regulari-
ties. These are chances. The reduction of chance to law will
consist, ordinarily, of determining more facts regarding the
chances and also in so extending the boundaries of the original
universe of discourse that new and theretofore unobservable
regularities will appear.
In problems of genetics the occurrence of an event said to be
due to chance may be ascribed to two separate but independent
sets of conditions. The internal conditions are those which are
entirely confined to the original universe of discourse of the
problem—as for instance, the conditions of the gametes in the
chance union of a Mendelian hybrid. The external conditions
are those which are not centered in the immediate elements. They
are such as age, strength, and the like, of the gamete producing
animals. Let # represent the chance occurrence of any event,
and let a, b, c, . . . represent a series of internal conditions
either known or unknown, and let the coefficients A, B, C,.. .,
ete., represent the intensive value of a, b, c in determining the
result. Similarly let m, n, o represent certain external condi-
tions and M, N, O their coefficient of intensive value. Then the
formula for the chance occurrence, ¢, of an event becomes
==] (Aa, Bb, Ce... Mm, Nn, Oo...)
As far as I can find in the recent literature of genetics the
| n of chance has appeared with three different uses.
No. 525] SHORTER ARTICLES AND DISCUSSION 569
used first to describe the degree of probability for the crossing
of individuals which differ more or less from one another. In
this sense one may say the chance of producing a cross varies
with the relative distance of the individuals producing the
gametes in the Linnean classification. The second use of chance
is that concerned with the occurrence of a mutant in those
theories of the origin of variation through mutation. In this
sense one speaks of a mutant as a chance or sport variety. The
third type of usage has grown up in the literature of Mendelian
crossing and of sex determination according to the male and
female producing spermatozoa of arthropods. In this third
type of instances the chance is reduced to the occurrence of one
of two events.
It is the purpose of the present note to apply the formula of
chance as previously given to these three separate uses of the
term.
1. Take, for example, the type of the first usage mentioned
above—the chance of a cross between different varieties and
different Linnean species. If œ represents the chance of a
cross between any two individuals, then the occurrence of that
cross is determined by a series of internal conditions a, b,
c, etc., which rest entirely within the structure of the gamete,
as for instance, the innate characters of the centrosomes
or the chromosomes. These are entirely contained within
the cell itself and are, therefore, independent of any external
modification. It is they, in all probability, that determine
the amount of cleavage of a zygot produced from the union
of gametes from individuals of different species, as for instance,
when the eggs of Rana fusca are fertilized by sperm of the Tri-
ton, but development stops suddenly after a few irregular cleav-
ages. The logician would say that these internal factors repre-
sented the conditions contained within the original universe of
discourse of the particular problem in question. The union is
also determined by external conditions m, n, 0, ete., which lie
without the gametes, as for instance, the ripeness of the eggs, as
shown by Hertwig in experiments on the sea-urchin, or by the
presence of alkaline in the water, as given by Godlewski when
he crossed the sea-urchin with a crinoid Antedon. These ex-
ternal conditions are those that lie without the original universe
of discourse of the problem.
2. Take, as a second usage of chance, the chance production of |
570 THE AMERICAN NATURALIST [Vou XLIV
a mutant. Let ¢ represent again such a chance occurrence. Then
¢ is a function of a, b, c, certain difficultly understood conditions
which seem to reside within particular gametes and produce a
new variety, differing considerably from the parental forms.
The various occurrence of mutants among domestic animals
probably resulted from such internal conditions. The very light
silver cat, Chinnie, made his appearance about 1878, and has
been the stock ancestor from which all the line-bred silver cats
have since been produced. No external factors determining the
occurrence of this sport could be traced. DeVries, who, of
course, emphasizes these chance occurrences of the mutants,
seems to believe that the internal conditions are alone respon-
sible for these chance variations, yet MacDougal is said to have
produced mutants of the evening primrose by salt solutions. If
this observation is borne out by subsequent investigation, such
mutant-producing factors would be represented by m, n, o of our
formula, the external conditions for the production of chance oc-
currence ¢, in this case the mutant.
3. Lastly, the concept of chance is of frequent occurrence in
Mendelian literature. The Mendelian formula for the produc-
tion of generation F! demands that the independent inheritable
characters shall separate in the gametes of F! and recombine
according to the pure law of chance, and Mendel’s work on peas
bears this out to a remarkable degree of accuracy. Similarly if
we believe that the sex of certain arthropods is determined by
male and female producing spermatozoa, but the egg is neutral,
we must assume that the determination of sex is purely a matter
of the chance union of the male or the female producing sperma-
tozoa with a neutral egg. Nor in this case is the formula of ¢
without its significance. The work on certain parthenogenetic
forms shows that certain spermatozoa, those without the acces-
sory chromosome, are degenerate and presumably non-func-
tional. This degeneration is obviously an internal condition, a,
of the formula, but since it is known that various sex ratios ex-
ist all the way from the approximate one to one of many of the
mammals to the very disproportionate ratios, approaching par-
thenogenesis in the nematodes, it may be supposed that this in-
ternal degeneration of certain of the spermatozoa is itself the
function of other and unknown variables. Again, the external
conditions m, n, o, such as age, maturity, nutrition, ete., may
also have an influence upon the chance oecurrence of the sex-
producing factor of the spermatozoa.
No.525] SHORTER ARTICLES AND DISCUSSION 571
The formula has perhaps an advantage, therefore, in suggest-
ing a definite usage of the concept of chance in these problems,
and also of suggesting, what writers sometimes confuse, the
marked difference between external and internal determining
factors. It rests upon a definite logical issue. Every scientific
problem arises in a more or less definite universe of discourse.
The limits of this universe of discourse determine the possibility
of discovering regularity among the experiences it defines. Such
internal regularity gives law, its absence, chance. This defi-
nition, therefore, gives to chance a definite and precise meaning,
capable of an exact usage in scientific enquiries. It does not in-
volve the affirmation nor the denial of the ultimate uniformity
of nature.
ARTHUR S. DEWING.
CAMBRIDGE.
NOTES AND LITERATURE
ANIMAL STRUCTURE AND HABITS
Proressor R. Hesse and Professor F. Dofiein have undertaken
the preparation of a general work on the structure and habits
of animals, of which the first volume? has just appeared. This
volume deals in a most complete way with the animal as an
independent organism and the authors reserve for subsequent
treatment the consideration of animals in relation to their en-
vironment. After an introduction which deals with life, proto-
plasm, the cell, animals and plants, the theory of descent, ete.,
the subject matter of the volume follows in four books dealing
with the statics and mechanics of the animal body, its metabo-
lism, powers of reproduction and inheritance, and the nervous
system and sense organs. A final section takes up the relation
of the parts of the animal to the whole. As a sample of the
thoroughness with which the subject is treated the contents of
the first book may be taken. This part opens with an account
of the shapes and movements of the unicellular animals followed
by a consideration of these aspects of the multicellular forms.
The skeleton in the invertebrates and vertebrates is fully de-
scribed. The power of animals to float in water and in air is next
considered, and the remainder of the book is given over to a
presentation of locomotion proper. This includes movements
by cilia and by muscles and under the head of muscular loco-
motion is considered locomotion by steps such as is seen in
leeches, ete., by wriggling as seen in snakes, eels, ete., and by
means of lever appendages. This last section includes swimming
by appendages, springing, running, climbing and flying, and the
last of these is discussed in relation to insects, bats and birds.
The treatment is rich in examples and abounds in well-con-
structed diagrams and clear illustrations. The remaining sec-
tions of the book are equally full and exhaustive.
The subject matter, though often complicated, is treated in an
***Tierbau und Tierleben in ihrem Zusammenhang betrachtet,’’ von R.
Hesse und F. Doflein, Band I., Der Tierkérper als selbständiger Organismus
on R. Hesse. Leipzig und Berlin, B. G, Teubner, 1910, 8vo, xvii + 789 pp.,
480 figs., 15 Taf.
l 572
No. 525] NOTES AND LITERATURE 573
unusually clear way and is free from unnecessary technicalities ;
in fact the treatment may be said to be popular in the best sense
of the word. This perhaps is the reason the book has been set
in Gothie instead of Roman type, a fact which will appeal to the
average German reader, though perhaps not to those outside
Germany. The material is thoroughly modern without, how-
ever, involving the reader in present-day disputed questions, and
in some respects the volume may he looked upon as a rewriting of
the ground covered by Bergmann and Leuckart’s ‘‘ Anatomisch-
physiologisch Uebersicht des Tierreiches.’’ To this work the
author acknowledges much indebtedness and appropriately dedi-
cates his volume to its authors. In the revival of interest in
the study of form and function Professor Hesse’s volume should
find its place on the book shelf of every zoologist.
G. H. Parker.
PLANT PHYSIOLOGY:
Dr. KAUFFMAN has published a very interesting paper on the
influence of various substances on the sexual and other charac-
ters of certain species of Saprolegniaceae. Thorough studies
of this kind are likely to add much to our knowledge of the biol-
ogy of the fungi and will eventually, no doubt, furnish a mass
of data which may be of material aid in the solution of some of
the fundamental problems of evolution and variation.
One notable advance made by the author is the use of pure
cultures obtained from single zoospores. A very successful and
apparently simple method of obtaining the single spore cultures
is described. It consists in making dilutions of zoospores in
sterile water and sprinkling them with a pipette on the surface
of a gelatine plate where they can be located with the microscope,
and when they have germinated, they may be transferred to
other plates or tubes.
The author does not state how many generations of each or-
ganism were grown from the same original single zoospore cul-
ture under the same conditions. We infer from his account,
however, that in most cases the transfers were made from por-
tions of the mycelium or gemmæ and were in the nature of vege-
tative reproductions rather than new generations.
- 161A Contribution to the Physiology of the Saprolegniaceæ, with Special
Reference to the Variation of the Sexual Organs,’’ C. H. Kauffman (Annals
of Botany, No. 87, Vol. 22, p. 361, July, 1908).
574 THE AMERICAN NATURALIST [ Vou. XLIV
We doubt whether some of the conclusions reached, in regard
to the causal nature of the various chemicals used in the differ-
ent cultures in producing oogonia and other changes in certain
of the species studied, should be accepted without further study
and more conclusive evidence. The author says: ‘‘The results so
far indicated show that it is possible to produce, where hitherto
they were believed to be absent, antheridial branches of the
normal type known in other species of the family, and that their
production is conditioned by the presence of definite inorganic
salts.” The fact that antheridial branches appeared quite con-
stantly in cultures containing certain inorganic salts, does not,
in our opinion, necessarily prove that their occurrence was due
entirely to the action of such salts. In order to make such a
conclusion justifiable, it would be necessary, at least, to carry
on a very long series of cultures, covering many generations of
pedigreed forms originating from different individuals of the
organism under investigation, to say nothing of other possible
factors which may be unknown. It seems probable from recent
investigations by Miss Wakefield? and others that there are fer-
tile and sterile races or strains of species which differ in no other
respect from each other and apparently do not depend upon
the presence of any particular inorganic salt. An organism re-
produced vegetatively would also presumably tend to be more
constant in its behavior and show less variation than when each
-hew generation was produced from spores.
r studies of pedigreed strains of many generations of
Gleosporium and Colletotrichum started from single spores lead
us to the conclusion that there are some other factors or forces
involved in the variations which oceur in different generations
from single spores which have no perceivable connection, so far
as yet determined, with the composition of the medium in which
they grow. Apparently spontaneous variations appear in such
series of generations at the most unexpected moment under ap-
parently identical conditions of environment and culture media.
We say apparently because it is probably beyond our power at
present to determine much less to control all the factors con-
cerned in the growth and behavior of an organism.
* Wakefield, E. M., ‘‘Die Bedingungen der Fruchtkorperbildung bei Hy-
menomyceten, sowie das Aufftreten fertiler und _ steriler Stamme bei
denselben,’’ Naturwis. Zeitschrift fur Forst- und Landwirtschaft, 7. Jahr-
gang, 1909, 11 Heft, pp. 521-551, 1909.
No. 525] SHORTER ARTICLES AND DISCUSSION 575
Some series of cultures which produce no oogonia are believed
by the author to possess a distinct physiological character in this
respect, whereby they can be readily separated from series which
produce oogonia. If these organisms obey the same general laws
as those with which we have been working, it would be injudici-
ous, at least, to say positively that they do not produce oogonia
without having grown them for many generations and from dif-
ferent individuals of the same origin.
The idea, that the same conditions of nutrition, temperature
and general environment always produce the same results upon
the individuals of a species of organism, has, we believe, as yet
no sufficient basis in demonstrated fact. The suggestion of the
author, that a standard for the measurement of species compar-
able to the standards used in physics and chemistry, can be de-
vised, is, we fear, a delusion and indicates a failure to recognize
the apparently fundamental fact of biology that organisms pos-
sess inherent tendencies or forces which may enable them to vary
without necessary dependence on any particular nutritive sub-
stance or environmental condition which can be at present
definitely determined. The causes of these variations or muta-
tions may perhaps be determined when we are able to recognize,
analyze, measure and control all the numerous delicate complex
factors concerned, many of which are now probably beyond us
and not even surmised.
At another point essentially the same solution of the ever-
vexing and recurring species question is given as follows: ‘‘ At
first thought this seems to indicate that no separation can be
made of the different species of Saprolegniacew by means of con-
stant characters. We can, however, use the resources of the
chemist and physicist, and, by stating the exact conditions of
culture establish a standard to which all forms may be referred.”
It is further stated: ‘“‘It would seem necessary, then, in mono-
graphing such a family as the Saprolegniacee to refer all the
species to definite conditions, which should be uniform for all,
and to determine in each case the variability to the extreme at-
tainable limits.’’ If it were practicable to apply such a test,
there is apparently little to justify the expectation that it would
prove satisfactory. That mutations or variations may be in-
duced or brought into expression by changes in conditions or
other stimuli, is probably true, but to determine among the mul-
tiplicity and obscurity of the factors in any particular ease, just |
576 THE AMERICAN NATURALIST (Vor. XLIV
what these conditions or stimuli are, is exceedingly difficult, even
though we assume in the beginning that the organism under in-
vestigation has no latent hereditary possibilities of change in-
directly or not at all dependent upon its immediate environment.
Our work with Gleosporium and Colletotrichum, part of
which is yet unpublished, indicates that so far as these organisms
are concerned, at least, no such method would prove practicable;
as the same organism, so far as any morphological characters or
host relations serve to identify it, will frequently behave very
differently when cultures of the organism obtained from differ-
ent acervuli on leaves of the same host are made. This fact
might be easily explained, perhaps, by the assertion that such
forms are the elementary species of DeVries and others, or races
or strains, but this rather complicates than simplifies the prob-
lem. If there are numerous elementary species of the same
fungus to be found on the same host without recognizable morph-
ological differences, it is certainly questionable whether any
practical taxonomic work could be founded upon such a basis.
Until it can be demonstrated that an organism is entirely con-
trolled by its external environment and nutritive conditions and
all its hereditary expressed and latent characters are known, it
will be hazardous to base positive conclusions upon such data.
We must continually keep in mind and be prepared to make al-
lowance for the inherent hereditary characteristics and possi-
bilities of the organism which may possibly find expression in
any particular individual or generation.
The vast and complex problems of determining the origin and
cause of the form and behavior of even the simplest living organ-
ism is not perhaps to be so easily solved. The more it is studied
the more difficult it appears. All exact knowledge and data in
regard to these phenomena are to be welcomed, however, and the
more we come to appreciate the difficulties of the subject the
better able we should be to devise experiments that will yield
the necessary data which may eventually reveal to our finite
minds some of these profound mysteries of nature.
C. L. SHEAR.
Methods in Plant Histology
CHARLES J.
CHAMBERLAIN
Second edition, revised and much enlarged ; 272 pages, yas 88 illustrations, 8vo, cloth; net $2.25,
postpaid $2.3
HE first complete manual to be published on the subject of botanical micro-
technique. It contains detailed di
ections for collecting and preparing plan
material for microscopic investigation, pottin forth the advantages and disadvan-
tages of the different methods
Will no doubt find a place in every well-regu-
lated library, and will B: found very useful by
private students.— Plant World.
It is an excellent book for the individual
worker and for classes in collegesa.— Education.
A ee Guide in Tano
UL G. HEINEM
,12mo — net $1.50, postpaid $1,61
158 pages, interleaved, ccs 37 il
CLEAR and concise presentation of
bacteriological technique, designed phage
cipally as a manual for the medical g but highly useful also as
reference book for the biological teacher
workers in the fields of medicine and hygien
The instruction given is clear and accurate,
and the pra eos exercises are well selected.—
The Lancet (London).
A meat such as gas must mee very greatly
the practical class work, for which it is most ex-
cllently pete — American Journal of Medi ical
Scienc
m estigator, as well as for eyi
e directions are clear and concise, and every
Tar is described so carefully = it is hard to see
how the student can go as Physicians who
are rusty in bacteriology ciate do better than buy
this little book. The book is beautifully printed
and bound.—American Journal of Clinical Medi-
cine.
Animal Micrology:
Practical Exercises in Microscopical Methods
By MICHAEL F. GUYER
250 pages, 8vo, cloth; net $1.75, postpaid $1.88
[Be title of this book will sg set = scope. It is intended as a laboratory
manual for textbook use. Its a
of microscopic anatomy and adhe clear: RGF ie: details of procedure ra
than descriptions of reagents or apparatus.
s to introduce the student to the technique
rather
t account of the theoretical
side of microscopy is given to enable the student to ei ARA results from his
microscope.
The directions are simple, explicit, and com-
plete..—American Journal of Clinical Medicine.
The medical student will find it very useful as
guide to Spp work.—Journal of the pet
can Medical Ass
This is one of t ae cleanest works on microsco
ical technique we have ever seen, and is especially
suitable for the beginner. It is full of points,
tricks of technique not mentioned in other works,
and is one that pated siren and physician should
have. iaat
uable EA: is strong through its ngia
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lucid. = peas eae gn raai a man long practi
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poset itions and reliable method of obtaining
a definite and comprehensive result. — Medical
Notes and Queries.
sox a ae and well-classi-
fied treatment. —Science.
The aes of the — recommended
are ap irably clear.— Natu
of the best and m ited reagia pagaen
aati e aa with which w
quainted.— American Naturalist.
textbook it can hardly be improved.
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terial with which he
Review
reparing ma-
is not piara —s chool
It does oes present in very clear form a judicious
selection of methods, including an score se un-
technical account of the mi d its —
principles, —— the ‘padengraduate
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and Psychology
ADDRESS DEPT. 33
Chicago
THE UNIVERSITY OF CHICAGO PRESS
New York
Cast of Head of Mummied Woman of the
“Basket People” (Cliff Dwellers)
This is the specimen which Professor H. H. Wilder restored to approximately its —
normal contours by treating with a pomen solution, as described in the American
Anthropologist, Vol. 6, No. 1, Jan.—Mch., 1904.
e restored subject has been molded and cast in our laboratory. The head
is tinted and is mounted upright on a black pedestal with incised label. Professor
Harris writes:—‘‘I have been out of town for a few days and on returning found
what I consider a most successful rendering of my ‘restored’ Cliff Dweller lady,
and wish to thank you heartily for attempting so difficult a task.’’
This head or bust is, perhaps, the only authentic likeness of a prehistoric Amer-
ican in existence. Copies, securely boxed, each............... 2c. cece eeentee ce eeee se ees $ 8.00
We can also supply the following casts, all colored after nature.
HOMO SAPIENS
Skull of Engis Man, restored portions indicated Price, $2.00
Skull and Mandible of Cro-Magnon No. 1 n much above the present
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Cranium of Cro-Magnon No. 2 Bae $3.00
Cranium of Australian Price, $2.75
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Series of nne, of ten races of man (intercranial casts) from the Te
College of Surgeons: Casts are alabaster, coated with stearine. Eac
brain has its individual pedestal and label Price, set of re $25.00
HOMO PRIMIGENIUS
Neanderthal Man, cranium and portions of meos = femora, 2 humeri, 1
us, 2 ulnæ, 1 peri 1 scap clavicle), a
with intercranial cast......... Price, 12 ioe tra Skull or Brain, each, $2.00
To facilitate the study of es anatomical peculiarities of this skull, a reprint -
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is included
Man of Spy No. 1 includes calvarium, lower jaw, right sup. max., portions
of clavicle and humerus, left radius, head of left ulna, right femur,
and left tibia and patella .......6..c0. sonene tenes Price, $11.00
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{eee ee ar $7.50
tle Gastar aye No Tor NoD roo aa ooh eaii ara ni anant $1.75
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_ Mesopithecus pentelici, male craniu . $1.50
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anthropoi m the fresh-water Miocene of Southern France)........- $2.25
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An 8-page illustrated description by the late Professor Marsh accompanies this
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> - ANATOMICAL LABORATORY OF CHARLES H. WARD
e “THE LENNOX,” WEST AVENUE ROCHESTER, N. Y.
VOL. XLIV, NO. 526 OCTOBER, 1910
3
THE
AMERICAN
NATURALIST
A MONTHLY JOURNAL
Devoted to the Advancement of the Biological Sciences with
Special Reference to the Factors of Evolution
CONTENTS
Page
Variations in Urosalpinx. Dr. HERBERT EUGENE WALTER - - - ~ 577
Nuclear Phenomena of Sexual Reproduction in Gymnosperms. CHARLES J.
CHAMBERLAIN - z ms - © = = a - = - - - B95
Nuclear Phenomena of Sexual Reproduction in Angiosperms. Professor D.
Hue = o - - = = 604
Shorter Articles and Discussion: Sterility, Dr.Max MORSE - - - = 624
Notes and Literature: Notes on Ichthyology President, Davip STARR JORDAN.
- - 634
The Mammals of Colorado, Professor T. D. A. COCKERELE - = -
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THE
AMERICAN NATURALIST
VoL. XLIV October, 1910 No. 526
VARIATIONS IN UROSALPINX
DR. HERBERT EUGENE WALTER
Brown UNIVERSITY
1. Introduction.—In a paper which appeared in 1898
Bumpus' showed that, in the case of Littorina littorea,
an introduced species shows more variability than the
same species in its original habitat. This Littorina was
recently so rare on the Atlantic coast that two pioneer
specimens were reported by Verrill from Woods Hole in
1875 while the first specimen found at New Haven was in
1880. Twenty years later it was probably the com-
monest mollusk to be found along the new England coast
and its range extended northward and southward con-
siderably beyond this area. Three lots of 1,000 each,
representing the former habitat of the species, were ob-
tained from the coasts of Wales, Scotland and England,
respectively, and these shells were measured so as to get
an index of their variability. Then ten 1,000-lots of the
introduced American shells were collected and measured
for comparison and it was found that nowhere in any of
the ten different localities, which extended from the St.
Croix River in Maine to Newport, R. I., could shells be
found that did not have a greater index of variability
than did the British shells. Duncker? working over
1Bumpus, H. C., 1898, ‘‘The Variations and Mutations of the Intro-
duced Littorina,’’ Zool. Bul., Vol. I, pp. 247-259.
2 Duncker, G., 1898, ‘‘Bemerkung zu dem Aufsatz von H. ©. Bumpus:
The Variations and Mutations of the Introduced Littorina,’’ Biol. Cen-
tralbl., Ba. 18, pp. 569-573.
577
578 THE AMERICAN NATURALIST [Vou. XLIV
Bumpus’s data afterwards by the most approved tech-
nical methods, confirmed his conclusion.
The oyster-borer, Urosalpinx cinereus Say, offers an
additional opportunity to test the relative variability of a
species when introduced into a new environment as com-
pared with the same species living in the original habitat.
This mollusk is a native of the Atlantic coast, living par-
ticularly on the oyster beds, where it causes considerable
damage. In 1871 Mr. A. Booth, of Chicago, first trans-
planted the Atlantic oysters to the Pacific coast where,
with varying success, they have since been maintained.
Two lots of these shells were obtained from the San
Francisco beds in 1898 and it was the original purpose
of this paper to compare these introduced California
shells with individuals from the Atlantic coast whence
they were emigrated.
The work was principally done at the Woods Hole re-
search laboratory of the U. S. Fisheries Bureau and I:
wish hereby to acknowledge the many courtesies received
from the officers connected with that bureau, and particu-
larly to express my indebtedness to Professor Bumpus
who suggested the original problem. I wish also here
to thank the following persons for aid in obtaining speci-
mens: Dr. Bumpus for 1,500 California shells; Dr. H. M.
Smith for 1,700 from Prince’s Bay, Staten Island; Mr.
G. W. Hunter, for 1,000 from Norwalk Harbor, Ct.;
Miss M. E. Smallwood for 1,000 from Cold Spring Har-
bor, Long Island; Mr. C. T. Brues and Mr. A. L. Melan-
der for 8,000 from Woods Hole, Mass., in 1902 and 1903;
and Mr. ©. S. Bennett for 4,000 from Woods Hole in
1908. Finally, I am particularly under obligation to Dr.
J. Arthur Harris, who very kindly passed the manu-
script under his statistical eye. It should be added that
while Dr. Harris is responsible for much that does not
appear he is in no way committed to what remains.
2. Methods.—In collecting, only living specimens were
taken, thus eliminating beach-worn shells, and collecting
was always done ‘‘ systematically at random’’ (Daven-
r?
No. 526] VARIATIONS IN UROSALPINX 579.
port) so that any lot would, as far as possible, be typi-
cally representative of its locality. Lots of 1,000 were
taken and shells not immediately measured were simply
preserved in formalin until opportunity for making use
of them arose.
In ascertaining statistically the variability of any lot
of shells it was necessary to select for measurement two
easily definable dimensions common to every shell and
take the ratio of these two dimensions for reasons which
will directly appear. The dimensions selected were the
total height of the shell (a to b, Fig. 1) and the greatest
dimension of the shell-aperture (a
to c, Fig. 1). It was possible to de-
termine these standards on Urosal-
pinx by the use of calipers with a
considerable degree of accuracy.
Any other dimensions which would
lend themselves equally well to ac-
curate measurement would have
served quite as well to establish a
criterion from which a comparison
of variability in different lots of
shells could be computed, since it
was the fact of variation, and not Fro. 1. a-b=height of
the direction or character of it that S08) ©°™ greatest mouth
was the object of the inquiry.
The ratio of the two dimensions was used instead
of a single dimension in order to eliminate as far
as possible heterogeneity referable directly to growth.
Had height alone, for instance, been used then groups
of shells would be related to each other with reference to
their variations in size or age only, and all that could be
said in comparing lots from two localities would be that
those in one locality averaged taller or shorter, and pre-
sumably, therefore, were older or younger than those
from another locality. This would not.be a suitable index
for variation in form. On the other hand, when the ratio
of two dimensions is taken, then the factor of absolute —
580 THE AMERICAN NATURALIST [Vou. XLIV
size is eliminated, while the factor of form remains.
Thus a shell 20 mm. high with a greatest shell-aperture
of 12 mm. would fall in the 60 per cent. class (20:12 =
60 per cent.), as would also a smaller shell 15 mm. high
with a greatest shell aperture of 9 mm. (15:9—60 per
cent.), while shells of the same height as the first, but with
a 14mm. greatest shell aperture, would rightly represent
a variation in form since they fall into a different (70
per cent.) class (20:14—70 per cent.). This distinc-
tion may be more apparent by reference to Fig. 2 where
ele saps bb GT Ge 65 G4 63 62 GI 60 53 58 57 5655 54
5
The different classes of variants occurring in a specimen lot of one
thouss and shells to show how size, or the factor of growth, was eliminated in
classifying the variants. The shells in the vertical lines all in the same per-
cent Gi pA although their size (height) differs. The shells in the horizontal
lines are in different percentage classes, although their size (height) is alike
single representatives of all the different classes of var-
iants that appeared in a certain thousand-lot of shells
are arranged to show this point. Here the shells in any
horizontal row are the same height, and have, therefore,
presumably reached the same stage of growth, but at the
same time they are all unlike in form since those at the
left have larger ‘‘greatest shell apertures” than those at
the right. On the contrary, all the shells in any vertical
No. 526] VARIATIONS IN
UROSALPINX 581
row, although varying in size, fall into a single form-
group as determined by the ratio between total height
and the greatest shell-aperture.
such as that used by Bumpus for his work on Littorina
made it possible to read the ratio of the two dimensions
directly from a graduated arm without trouble of com-
putation, thus greatly lessening the tediousness in ob-
taining the data.
A measuring machine
3. Are Variation Curves of any Locality Distinctive
for that Locality?—Tests were first made to ascertain
how far the personal element in making the measure-
ments could affect the results, since judgment in the use
of calipers and in the manipulation of the measuring ma-
chine are by no means invariable factors. One such
test, which is typical of several which were made, is
shown in Table I, where the same lot of shells was twice
measured.
TABLE
I
THE SAME LOT OF A THOUSAND SHELLS TWICE MEASURED TO SHOW AMOUNT
OF ERROR IN MANIPULATION,
Percentage 54 {55 56 | 57 58 | 59 60 | 61 | 62 | 63 | 64
Class.
00 | Of | 05
09
69 |Arithmet-| Standard’ Probable’
‘ical Mean. | Deviation.| Error.
First meas- q 2| 2 5 | 28|/58/118/185/182 171 139
uring
Second 2| 2| 4 |25 66/128/182/179/176/120|
measuring |
49
59
3815/5/2] 62.101 | 1.992 |=2ô300
(33118! 4| 2| 62.071 | 2.088 | +.0314
Difference | 030 | _.096
The numbers ought to be identical. Their deviation
from exact similarity represents the imperfections of
manipulation and it will be seen that according to this
test a difference of .096 in the standard deviation with
a probable error of about + .03 may be regarded due to
imperfect technique.
Now in order to test whether the variation is charac-
teristic and constant for any locality whence the shells
came, two 1,000-lots were gathered on the same day in
1898 from the same restricted group of rocks on Nobska
Point, Woods Hole, by no means thereby exhausting the
582 THE AMERICAN NATURALIST [Vou. XLIV
supply. The figures for these two lots are shown to-
gether in Table II.
TABLE II
Two Lots or SHELLS OF ONE THOUSAND EACH TAKEN FROM THE SAME
ROCKS AT THE SAME TIME TO SHOW THE PROBABLE VALIDITY OF
PLACE-MODES.
oe 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 el 63 BE | 66 aa 67 | 68 | 69 | A.M, ac T fes E.
eee Sg OS |
First lot 2 | 3| 20| 40| 80/150 1491196) 157/112 aa 21) | 10 4 1 | 61. 737 2.152 .0323
Second lot | 2 | 2 | 31, 14) 61) 79/144 rca 106 55| 25) 10| 7 61. 694 2.234 .0336
Difference 043 082,
The close resemblance of these two lots, which show a
difference in standard deviation (.082) less than that
shown when the same lot is measured twice (.096) as just
indicated in Table I, warranted confidence in the proba-
bility that all the shells from a given place, when col-
lected at the same time, exhibit the same characteristic
sort of variation which may therefore be regarded as
distinctive for that particular locality. Furthermore, a
glance at Table III will show how widely the shells of
various localities may differ with regard to the character
and degree of their variability, a fact that assures us that
in U rosalpins we are dealing with a form whose varia-
tion is considerable enough to furnish favorable mate-
rial for quantitative treatment.
* Formulas for standard deviation and probable error of standard devia-
tion are found in Davenport’s Statistical Methods (Davenport, C. B., 1899),
as follows:
Bum- of Standard deviatio
\ [ (deviation of class from mean)? Y pain ‘of eer or
Number of variates
SV (#- f)
n
Probable error of standard deviation —
Standard deviation
o
——————— ON Ba a , E. — + 0.6745 ———
2 X number of variates EE = 0.67 2n
x
+ 0.6745
No. 526] VARIATIONS IN UROSALPINX 583
TABLE III
Two Lots or SHELLS OF ONE THOUSAND EACH TO SHOW EXTREMES OF
VARIATION.
Percentage | 59 | 51 | 52 | 58 | 54 | 55 | 56 | 57 | =| 58 | 59 | 60 | 61 | 62 | 63
Class.
Devil’s Foot| 1 | 07} 2| 6 | 22| 38] 99 | 144) 193) 217| 163 78 | 25) 14
Prince’s Bay 4| 5 9| 36) 45| 65| 79 | 132| 84
Clas:
66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | A.M. | o |P.E.
ee 64 | 65
Devil’s Foot | 3 | 58.358 |1.849|.0279
Prince’s Bay | 83 | 117| 75 | 88 | 83 | 42 | 33| 15| 2 63.976 3.407 0514
Difference 5.618! 1.558
4. A Comparison of Atlantic with Pacific Shells. —In
the summer of 1898, following the method employed by
Bumpus with Littorina, 7,006 Urosalpinx shells from
various localities near Woods Hole were obtained and
measured, with which were compared 1,528 introduced
shells from two localities in California. From Table IV,
in which these data are brought together, it will be seen
that Bumpus’ s work on Littorinais apparently confirmed,
that is, there is more variability in the introduced than
in the endemic form, although the margin of probable
error permits an overlapping in some instances.
_
TABLE IV
ATLANTIC AND PACIFIC SHELLS COMPARED.
Locality. a A. M. o P. E.
West Shore 1,001 58.928 2.339 +.0352
Penzance Point 1,002 61.718 2.137 +.0412
obska Point 1,002 61.737 2.152 +.0324
Woods } Nobska Point 1,001 61.944 2.234 +.0337
Hole ) Nobska Point 496 66.944 2.366 +.0507
. | Barnacle Beach 998 63.932 2.604 +.0393
Big Wepecket 1,006 57.426 2.052 +.0308
Mid Wepecket 500 57.606 2.098 +.0447
Average 61.066 2.335 +.0386
poe Belmont Beds 1,008 59.051 3.023 +.0454
San Francisco Bay 220 60.892 3.361 +.0703
Average 59.664 3.138 +.0538
Difference .803
5. Shells from Buzzard’s Bay and Vineyard Sound
Compared.—For the sake of scientific peace of mind the
584 THE AMERICAN NATURALIST [Vou. XLIV
incident should have been closed at this point, but uncer-
tainty as to the degree in which the element of time took
part in influencing the place-modes of variability led to
the examination during the following summer of several
thousand more shells. Four convenient localities near
Woods Hole (see Fig. 3) where Urosalpinx was abundant
were selected and three lots of 1,000 each were collected
from each of these localities at intervals of two weeks
apart. The data obtained from these shells is arranged
in Table V.
TABLE V
Woops Hote SHELLS ARRANGED TO SHOW PLACE VARIATION AFTER Two
WEEKS INTERVALS OF TIME.
Locality. Ca bg N pans of} A.M. o P.-E,
July5 | 1,000 | 58.669 | 2137 | +.0322
West Shore | July 21 | 1,000 | 59.598 | 2211 | +0333
Aug.5 920 | 60.308 | 2.211 | +.0328
Buzzard’ s Average 59.503 |
my Penzance | July5 | 986 | 58458 | 2137 | 20004
aint | July 21 | 1,000 8.030 | 2135 | +.0322
Aug.5 | 1,000 | 60.308 | 1.982 | 0323
Average 58.888
July 5 | 1,000 2.085 | 2.040 | 4.0307
Nobska | July 21 | 1000 | 62.690 | 2172 | +0327
Aug.5 | 1,005 | 64.022 | 2312 | +0347
Vineyard Average 62.934 |
Sound ] Jul ~ 60.97 ‘ 10
Barnacle | July 5 | 1,036 | 60.978 | 2.093 | -£.03
Beach | July 21 | 1,001 | 61.925 | 2119 | =.0319
Aug.5 | 1,001 | 63.281 | 2186 | +.0329
7 Average | 62.048 | |
From Table V it will be seen that in each of the four
localities the arithmetical mean (A.M.) increased stead-
ily, except for the Penzance Point—J uly 21—lot of shells.
This general increase may be due to the fact that, as the
season advanced, there were fewer young shells in any
1,000 lot. The young are produced in May and June
from individuals that have wintered over, so that early
in July the Urosalpina community is made up of old
adults from the preceding year and of young of various
sizes. A month later the population is more uniform,
No. 526] VARIATIONS IN UROSALPINX - 585
Buzzarns Bar
Mh,
de?
Vineyaro Souno
Fic. 3.
due to the rapid growth and approaching maturity of the
young ones. That the ratio of the two dimensions used
changes somewhat with age is shown in a later table
(Table VII), a fact that somewhat complicates a compar-
ison between shells of any two localities. It will fur-
thermore be observed that the variability of the Vine-
yard Sound shells as indicated by their standard devia-
tion increases steadily from July 5 to August 5, reaching
its maximum upon the latter date, but that for both the
Buzzard’s Bay localities the same is not true; on the con-
trary, in the case of Penzance Point the August 5 collec-
tions showed the least variability of any time. The fact
that the maximum of the shifting seasonal variation does
not occur at the same time in localities almost within
sight of each other, as in the present instance, plainly
indicates that comparisons of variabilities based upon
the time-factor alone do not take everything into consid-
eration. The shells from Buzzard’s Bay range in their
arithmetical mean from 58.030 to 60.308 while those from
Vineyard Sound, separated from the former only by the
narrow tongue of land on which the village of Woods
Hole is located, form a distinct class ranging from 60.978
to 64.022. Here is a distinct place difference in the oie
of the two general localities in question.
Shells obtained from other localities in Buzzard’s Bay
586 THE AMERICAN NATURALIST [Vou. XLIV
and Vineyard Sound conform quite closely with respect
to their arithmetical means to the standards above men-
tioned.
6. Time and Place Factors Compared.—When a com-
parison of the standard deviation of these 1899 shells is
made to ascertain whether the greater variability is as-
sociated with time (due to inherent germinal modifica-
tions), or with place (associated with environmental
modifications), it appears that while time is rather the
more important factor, yet the result is not uniform and
convincing. This comparison is shown in Table VI, in
which the difference between the standard deviation of
the July shells of each locality with the July 5 shells of
three other localities is obtained to indicate differences
due to place, and second, the difference between stand-
ard deviation of the July 5 shells in each locality and
those of July 21 and August 5 for the corresponding lo-
cality are reckoned to show the effect of time.
TABLE VI
A COMPARISON OF THE DIFFERENCES IN THE STANDARD DEVIATION VARIA-
BILITY OF THE 1899 Woops HOLE SHELLS ARRANGED ACCORDING
TO THE PLACE-FACTOR AND THE TIME-FACTOR.
j Fisoo Diferanois (July 5). 7 Time Differences.
— | win T eee July 5. July 21. | August 5.
-| bee
— .097 .025 .053 | Nobska Point 132 272
.097 — -122 .044 West Shore .074 .080
.025 122 — .078 | Penzance Point .120 .033
.053 .044 .078 — Penzance Beach .026 .093
.058 088 .075 .058 Average .088 119
In Table VI, if we first consider the case of the Nobska
Point shells in the top line of the table and utilize those
collected upon July 5 as a standard for comparison it ap-
pears that shells from the same locality but collected two
and four weeks later show a greater difference in varia-
bility (standard deviation) than shells collected from any
of the three other neighboring localities upon the same
date of July 5. That is, the factors dependent upon time
No. 526] VARIATIONS IN UROSALPINX 587
play a greater part in determining the amount of varia-
bility than do the factors dependent upon place.
Furthermore, there is a greater difference of variability
after four weeks (.272) than after two weeks (.132)
have elapsed, just as would be expected if a progressive
time change is taking place. The same general result
appears also when an average of the four localities is
reckoned, as shown in the bottom line of the table, but
an examination of. the second, third and fourth lines of
the table reveals several instances in detail of non-con-
formity to this apparently general conclusion that time
has more to do with determining variability than place.
It is apparently safe to conclude, however, that the fac-
tors dependent upon time are at least as important, if
not demonstrably more so, than those dependent upon
space or locality.
TABLE VII
Woops HOLE SHELLS ARRANGED ACCORDING TO THEIR SIZE.
Height in mm. myn No. of A. M. Per Cent. o P. E.
11 96 64.070 3.487 + .1753
12 1 63.911 3.558 + .1445
13 252 63.372 3.465 + .1049
14 341 62.983 3.954 + .1029
15 524 62.940 3.602 + .0755
16 866 61.960 3.020 + .0489
7 1,296 61.595 3.146 + .0417
3 2,033 61.171 3.124 + .0325
) 2,328 ).913 3.143 = OSI
) 3,366 .004 3.209 + 0227
4,404 914 3.056 + .0219
, 4,8 .739 3.122 + .0213
3 3,836 60.507 2.881 4 0222
t 2,854 TIL 2.951 + .0276
) 1,782 856 2.943 3 0322
; 706 2 + .0412
7 539 .520 2.704 + .0555
239 :213 2.520 + 0717
) 109 .654 2; Hi 1828
) 63 .805 2.740 + .1646
30 334 2.182 + .2455
) 23 665 1.916 d .1905
4 6 332 4.015 + .7818
t 12 1.083 3. + .4141
5 j .600 2.059 + 4392
J ).000 8.185 +2.2554
7 4.000
Total 30,903
588 THE AMERICAN NATURALIST [Vou. XLIV
T. Variations due to Age.—It is indeed true that as
the snail grows older not only is there a change in the
total height of the shell, as would be expected, but also
the ratio of the largest shell-aperture to the height
diminishes in a definite way and the standard deviation
becomes generally less. In other words, the older the
shell becomes the less is the relative size of the largest
shell-aperture to the total height and the less does it
tend to deviate from the arithmetical mean. In Table
VII the total number of shells measured in 1898, 1899,
1900 are arranged according to their height to illustrate
this fact.
8. Staten Island and California Shells Compared.—
In 1900 shells were obtained from several additional lo-
calities, among which were 1,665 from oyster beds on
Prince’s Bay, Staten Island. This lot of shells has a
special interest because it was from this particular lo-
cality, according to Dr. H. M. Smith, of the U. S. Fish
Commission, that the oysters, and accidentally with
them the Urosalpinx, were obtained for transplanting
to San Francisco in 1871. A comparison of the Staten
Island shells with the California shells appears in Table
VIII.
TABLE VIII
A COMPARISON OF CALIFORNIA SHELLS WITH THOSE FROM STATEN ISLAND.
be, AM. | ee |
| | oe.
California 1,528 59.741 3.286 | +.0398
Staten Island 1,664 63.166 3.508 | 12
From this table one of three conclusions must be
drawn: (1) That the introduced California shells vary
less in their new environment than they did in the place
they came from or (2) that the Staten Island shells have
increased remarkably in their variability since 1871, or
(3) that place-modes in which time element is not known
are of little value in working with organisms of this
9. Shells of Successive Years Compared.—Further-
No. 526] VARIATIONS IN UROSALPINX 589
more, the analysis of the 1899 shells indicates that a
proper comparison of place-modes of variability could
be made only on material of the same relative age, which
presumably could be approximated best by collecting
the shells in neighboring localities at the same time or
in any one locality at the same time in successive years.
Consequently lots of 1,000 shells from each of the four
Woods Hole localities mentioned in Table V were col-
lected during the first week of August, with some omis-
sions, for several years. These data are assembled in
Tables IX and X.
In Table IX it is made apparent that, when the time
element is reduced to a minimum by comparing only
August 5 shells of various years, the shells of Buz-
zard’s Bay (West Shore and Penzance Point) fall into
a group distinct from those of Vineyard Sound (Nob-
ska Point and Barnacle Beach), at least so far as the A.
M. is concerned. The A. M. of 11,476 Buzzard’s Bay—
August 5 shells is 61.330 while the A. M. for 14,503 Vine-
yard Sound—August 5 shells, is 64.303. In no individ-
ual lot of Buzzard’s Bay shells does the A. M. reach as
high as the Vineyard Sound average and in no one lot
of the Vineyard Sound shells does the A. M. fall as low
as the Buzzard’s Bay average of 61.330.
The standard deviation of the August shells shows
no decided grouping with reference to Buzzard’s Bay
and Vineyard Sound, although those from the latter lo-
cality show a slightly higher total average which is
probably quite without significance. In general, then, it
may be said that during the first week of August the
Buzzard’s Bay shells show a lower ratio of greatest
shell-aperture to height (and consequently may be re-
garded as rather more advanced in their life cycle) than
those of Vineyard Sound, but that they present no sig-
nificant difference in variability.
In each of the two general localities which were more
exposed to the open water and the beat of the waves,
viz., Nobska Point and Penzance Point, is the variabil-
590 _ JHE AMERICAN NATURALIST [Vou. XLIV
TABLE IX
A COMPARISON or AUGUST SHELLS OF VARIOUS YEARS TO SHOW
PLACE-VARIATION.
Place, Time. Wiebe: A. M. T P. E.
r 1898 1,001 | 58.928 | 2.339 | -+.0352
1899 920 | 60.308 | 2.057 | =.0323
i 1900 405 | 60.711 | 2.042 | =.0484
1901 se = po
1902 1,000 | 63.251 | 3280 | +.0491
West Shore 1903 1,000 61.419 2.234 +.0336
1904 on mi rie
1905 1,000 | 61.086 | 2.012 | -,0303
1906
1907
1908 1,000 | 60.380 | 2.469 | -&.0372
Piradi Total 6,326 | 60.890 | 2.663 | -+.0160
sig 1898 1,002 | 61.718 | 2.737 | +.0412
1899 1,000 | 60.170 | 1.982 | =.0299
900 1,001 | 60.617 00 +.0316
1901 th ue ie A
1902 1,000 | 64.155 | 2938 | +.0443
seas, 1903 1,000 | 62.773 | 2086 | +.0314
1904 a = anh pe
1905 1,000 | 61.381 | 1.970 | +0775
1906 ae ee ee si
1907 Too searce|to collect
1908 i oa fast a
{ Total 5,150 | 61.870 | 2814 | +.0187
Total for Buzzard’s Bay 11.476 | 61.330 | 2.805 | +.0125
r 1898 | 2498 | 62.751 | 3.041 | +.0290
1899 1 64.022 | 2.312 | +.0347
1900 1,000 | 66.396 | 2.449 | +.0369
1901 hak pis ae
1902 1,000 | 66.775 | 2.707 | +.0407
rm 90 1000 | 64.605 | 2198 | +0321
1904 se a nae
1905 1,000 | 63.765 | 2.653 | +.0400
1906 =
1907 = ore
1908 1,000 | 63296 | 2.719 | +.0410
Vineyard Total 8,503 | 64.205 | 3.048 | +.0158
<
Sound 1898 998 | 63.942 +.0393
99 1,000 | 63.281 | 2.186 | =.0329
1900 1,000 | 66.798 | 2.052 | =.0309
901 = i i i
1902 1,002 | 66.085 | 2.851 | +.0354
soon 1903 | 1,000 | 68.526 | 2.546 | -0383
1905 'Tooscarce to collect
1906 ae a =i be
A 1907 kimsan Sanana: ae ere
: 1908 1,000 | 63.017 | 2.300 | +.0347
gore Total 6,000 | 64.442 | 2.602 | +.0160
| Total for Vi Hoo ee Yiosjerd Sound | 14,503 64.303, 2.865 | +.0113_
No. 526] VARIATIONS IN UROSALPINX 591
ity (standard deviation) greater than at West Shore
and Barnacle Beach, respectively, which were somewhat
-more sheltered situations.
Turning to Table X, where the August shells are
grouped by years rather than by localities, the A. M. is
seen to fluctuate with considerable regularity, reaching
in 1902 the highest average ratio. It seems not improb-
TABLE X
AUGUST SHELLS GROUPED TO SHOW YEARLY VARIATION.
Tons. Locality. No. SAM. G l PRO
West Shore 1,001 58.928 2.339 +.0352
Penzance Point 1,002 61.718 2.737 +.0412
1898 Nobska Point 2,498 62.751 3.041 +.0290
Barnacle Beach 998 63.942 2.604 +.0393
Average (5,499) 61.899 3.389 +.0218
West Shore 920 60.308 2.057 +.0323
Penzance Point 1,000 61.170 1.982 +.0299
1899 Nobska Point 1,005 64.022 2.312 +.0347
Barnacle Beach 1,000 63.281 2.186 +.0829
Average (3,925) 61.981 : 2.649 +.0202
West Shore 405 60.711 2.042 +.0484
‘spt ee 1,001 60.617 2.098 +.0316
1900 Nobska Poi 1,000 66.396 2.449 +.0369
Barnacle Beach 1,000 66.798 2.052 +.0309
Average (3,406) | 64,139 3.459 +.0281
West Shore _ 1,000 63,251 3.280 ; +.0491
Penzance Point 1,000 64.155 2.938 +.0443
1902 Nobska Point 1,000 66.775 2.707 +.0407
Barnacle Beach 1,002 66.085 - 2.351 +.0354
Average (4,002) 65.067 3.012 +.0227
West Shor 1,000 61.419 2.234 +.0336
Penzance Point 1,000 62.773 2.084 +.0314
1903 Nobska Point 1,000 64.615 2.128 +.0321
Barnacle Beach 1,000 63.526 2.546 +.0383
Average (4,000) 63.083 2.542 +.0291
Wes ; 61.086 2.012 +.0303
Penzance Point 149 61.381 1.970 +.0775
1905 Nobska Point 1,000 63.765 2.653 +.0400
Barnacle Beach — F o oo
Average (2,147) 62.077 2.718 +.0280
West Shore 1,000 60.380 2.469 +.0372
Penzance rg ES = 4 FO na
1908 Nobska Poin 1,000 63.296 2.719 +.0410
Barnacle Sean 1,000 63.017 2.300 +.0347 ~
Average (3,000) 62.321 2.802
592 THE AMERICAN NATURALIST [Vou. XLIV
able that the missing year 1901 would have furnished a
higher maximum than 1902, and that in some future
year the high average of 1902 may again be attained.
10. Dense and Sparse Population Compared.—T'wo
lots of shells collected in 1899 deserve a separate para-
graph. They represent the extremes among all the lots
collected with respect to the density of the population.
They came from localities on the eastern shore of Buz-
zard’s Bay about five miles apart and were collected
during the same week.
TABLE XI i
ae Oe Oke | 7 N | Ee A. M. ma w o | i es
Quisset-to- West-Shore 862 ~ 60.464 | 3.127 | +.0507
West Falmouth 1,000 59.091 1.913 +.0297
The Quisset-to-West-Shore lot was gathered over an
area extending fully a mile along the rocky shore and
they were so scarce that it was necessary to utilize the
low-tide period of two successive days in order to ob-
tain them, and even then only 862 were obtained instead
of the usual 1,000. The West Falmouth lot, on the con-
trary, were all taken within a few minutes from a single
rock about five feet in diameter without by any means
exhausting the supply.
It may be that the latter, as would be inferred by their
proximity, were more closely related to each other than
were the former, and consequently they might be ex-
pected to present less variation, or it is possible that the
Quisset-to-West Shore lot—representing the pioneers
or survivors in an apparently inhospitable area—suc-
ceeded in maintaining themselves because of their
greater variability (i. e., adaptability). Certain it is, at
any rate, that they represent the greatest variability
(standard deviation) of any lot of shells obtained from
the Atlantic coast except a thousand from West Shore
in August, 1902, and those already mentioned from
Staten Island.
11. Variation of the Species Urosalpina as a Whole.
—By combining the data of all the shells measured—a
No. 526] VARIATIONS IN UROSALPINX 593
total of 50,424—it is possible to approximate a measure
of the variability of Urosalpinx as a species much more
nearly than is possible with smaller lots of 1,000. Such
a combination is shown in Table XII, which will be seen
to furnish the figures for a curve of considerable regu-
larity in which the arithmetical mean is 61.662 and the
standard deviation is 3.367+.0071. This standard devia-
tion is exceeded in but a single instance among the
smaller lots which make it up—namely, in the 1,664
shells from Staten Island which show a standard devia-
tion of 3.508+.0412
TABLE XII
Per Cent. 50- DI b no u S u o 5
Ço. 4 15 £32 120 289 675 1,510 2,450 3,812
Per Cent. Owe ee Rae oe Oo
No. 5,052 5,491 5,861 5,515 5,115 4,225 3,647 2,357 1,714
Per Cent. e U w nn R uu a Dp Al
No. iia o3 -o Ri be er 8 4 1
A. M., 61.662. o, 3.367. P. E., +.007. Total No., 50,424.
12. Summary.—1. When two lots of 1,000 Urosal-
pinx shells each are taken from the same locality they
resemble each other sufficiently to indicate a character
typical for the locality.
2. Lots of shells from different localities vary widely
enough from each other to be easily distinguished, indi-
cating thereby that the varying environment associated
with different localities exerts a measurable effect.
3. Endemic Atlantic shells (with one exception noted
below) vary less than shells introduced into a new en-
vironment (California).
4. The shells of Buzzard’s Bay have a lower ratio of
greater shell-aperture to shell-height than those of
Vineyard Sound.
5. When shells from the same localities in successive
fortnights are compared there is an increase in the
ratio of greater shell-aperture to shell-height (A. M.)
and also a slight increase in variability as shown by
the standard deviation, except in the case of the shells
from Penzance Point.
-
594 THE AMERICAN NATURALIST [Vor. XLIV
6. When growth which we detect by taking into con-
sideration the time-factor is compared with the environ-
mental factors that depend upon place, the former ap-
parently plays the greater rôle in causing variations.
7. As Urosalpinx grows larger (older) the ratio of its
greatest shell-aperture to its height diminishes with
regularity and its standard deviation tends to become
somewhat less.
8. Shells from Staten Island whence the introduced
California shells were originally derived show greater
variability than the California shells.
9. When the August shells of successive years from
the same localities are compared the A. M. of the ratio
between’ the greater shell-aperture and shell-height
fluctuates with noticeable regularity, reaching a maxi-
mum in 1902. |
10. Shells from the localities more exposed to the
beat of the waves show greater variability than those
from the more protected places.
11. When dense and sparse populations are compared
the dense population shows less variability.
12. The average mean of the ratio of greater shell-
aperture to height of shell for 50,424 Urosalpinx shells
is 61.662. The standard deviation is 3.367+.0071.
13. Conclusion—So far as the statistical method is
able to reveal, it is extremely doubtful whether or not
Urosalpinx when introduced into a new habitat ex-
hibits greater variability than when in its native habi-
tat. The change in the variability appearing in succes-
sive fortnights in shells from the same locality as well
as in change showing itself in the August shells from the
same locality in successive years is marked enough to
indicate plainly the working of an ontogenetic variabil-
ity independent of environmental modification, that is,
a time-factor as distinguished from a place-factor. In
consequence of this it is practically impossible to collect
homologous lots of individuals of these shells upon
which the place- (or environmental-) factor may be ac-
curately determined.
NUCLEAR PHENOMENA OF SEXUAL REPRO-
DUCTION IN GYMNOSPERMS'!
CHARLES J. CHAMBERLAIN
UNIVERSITY OF CHICAGO
To the ecytologist the most interesting phases of a
plant’s life history are fertilization and the reduction
of chromosomes, processes which initiate the sporophyte
and gametophyte generations and which are of the ut-
most importance in any cytological theories of heredity.
We shall not attempt to define fertilization, but shall
simply state that, in our opinion, the process is essen-
tially uniform from its first appearance in the fusion
of equal gametes in the lower alge, up to the heterog-
amy of the angiosperms and, in our opinion, this fusion
of gametes, whether they be the equal gametes of the
lower alge or the unequal gametes of the higher plants,
always initiates a sporophytic phase in the life history,
a phase which normally continues until the reduction
of chromosomes brings it to a close and initiates the
gametophytic phase.
e gymnosperms have as yet only a single well-es-
tablished case of apogamy and not even a single case
of apospory, and, consequently, their only mode of re-
production, aside from occasional budding, is that re-
sulting from fertilization.
Since the significance of fertilization becomes more
intelligible with increasing knowledge of the partici-
pating gametes, it is of prime importance to know the
structure, evolution and behavior of the sperms and
eggs.
SPERMATOGENESIS
The sperms of fossil gymnosperms are almost un-
known, but it is safe to say that Cycadofilicales and
1A paper read by invitation before the Botanical Society of America,
Boston, December 30, 1909.
595 .
596 THE AMERICAN NATURALIST [Vou XLIV .
Cordaitales had swimming sperms, and further, that
they had no. pollen tubes, the pollen grains reaching the
female gametophyte directly, then discharging their
sperms about as in the living heterosporous Pterido-
phytes.
Definite knowledge of the structure of the sperm be-
gins with the cycads, where the sperms are so large that
they are easily visible to the naked eye. Broadly speak-
ing, their development is like that of most pterido-
phytes. In the most thoroughly investigated fern, after
the spermatogenous divisions have ceased, two ble-
pharoplasts appear in each cell, which then divides so
that each of the two resulting cells contains one nucleus
and one blepharoplast. From the blepharoplast there
is developed a more or less spiral band which gives rise
to numerous cilia.
In gymnosperms, with the exception of Microcycas,
Cupressus and occasionally, Ceratozamia, no spermatog-
enous divisions precede the formation of the cell which
is to produce the pair of sperms, and in these three
genera it is not known whether the blepharoplast ap-
pears any earlier than in the pteridophytes. I suspect
that it does not, but it is certain that in the cycads and
in Ginkgo two blepharoplasts always appear in the body
cell which is to produce the pair of sperms, and while
the blepharoplasts are at first very inconspicuous, they
finally become larger than the nuclei of most angio-
sperms.
The mature sperm of the cyead consists of a very
large nucleus surrounded by a thin layer of cytoplasm
in which is imbedded the spiral band with its thousands
of cilia. Compared with the sperms of the pterido-
phytes, the sperms of the cycads are immensely larger
and much less numerous. It must be a fact of some sig-
nificance that the living gymnosperms, with two or
three exceptions, have only two sperms, for the produc-
tion of sperms in pairs is universal from the liverworts
to the orchids. Whether the production of sperms in
pairs is associated with a separation of sexes is not
No. 526] SEXUAL REPRODUCTION IN GYMNOSPERMS 59T
known. Objections to such a suggestion are easily
raised, but the question seems worth investigation, es-
pecially since little is known of the behavior of the
chromatin during the mitosis by which two sperms are
produced from the body cell.
Except in the cycads and Ginkgo, there are no motile
sperms in living gymnosperms, but, in our opinion, the
transition is not so abrupt as some writers believe. The
definitely organized male cells of such genera as Sequoia
and Thuja look very much like the young sperms of a
cycad immediately after the division of the body cell,
the principal difference being the absence of the ble-
pharoplast, which is such a conspicuous feature in the
development of the sperms of cycads and Ginkgo. In re-
gard to the several genera with well-organized male
cells, the statement is made that there are no structures
which could be interpreted as the vestiges of blepharo-
plasts, but the figures accompanying the various ac-
counts are not convincing and it seems entirely possible
that vestiges may yet be found.
According to all the accounts, either as expressed in
the text or to be inferred from the figures, the body cell
in Taxew, Taxodieæ and Cupressex gives rise directly to
the male cells, there being no formation of sperms within
sperm mother-cells. The accounts may be correct, but
it must be remembered that a competent observer de-
scribed just such a condition in one of the cycads, where
it is now known that the sperms are formed within sperm
mother-cells from which they are afterwards discharged.
Among the Coniferales, the well-organized male cell is
found in the Taxacex, Taxodiew and Cupressee.
In the rest of the Coniferales, which means the Arau-
carieæ and Abietex, there are no organized male cells,
but only male nuclei lying free in the cytoplasm of the
body cell, and this cytoplasm not always sharply limited
from that of the pollen tube. Accompanying these male
nuclei there are often structures which might be inter-
preted as the vestiges of blepharoplasts. According to
some observers, one of the male nuclei is smaller than the
598 THE AMERICAN NATURALIST [Vou. XLIV
other, possibly indicating the future elimination of the
smaller nucleus.
That both the male cell of Thuja and the male nucleus
of Pinus are descendants of swimming sperms is not to
be doubted. The male cell of Thuja has lost its cilia and,
perhaps, is no longer formed within a parent cell, while
Pinus has gone further and no longer organizes a defi-
nite male cell. In this respect, the Pinus gametophyte
is more widely separated from the ancestral form than
is the gametophyte of Thuja.
In some genera, like Torreya and Taxus, the reduc-
tion has proceeded in another direction, two male cells
being retained, but one of them having become much
smaller than the other and having ceased to function,
indicating its future elimination.
It is interesting to note that in Coniferales, with the
exception of the Podocarpex, those forms with definitely
organized male cells have no prothallial cells in the pollen
grains, while those with the free male nuclei have re-
tained more or less of the ancestral prothallium; e. g.,
Pinus has retained the prothallial cells, but no longer
organizes a definite male cell, while Thuja has retained
the definitely organized male cell, but has lost the pro-
thallial cells. And further, those genera which have
retained the definitely organized male cell no longer
organize a definite ventral canal cell, having lost the
wall between the ventral canal nucleus and that of the
egg, a step toward the complete elimination of even
a ventral canal nucleus. Whether there are any causal
relations among these reductions is not obvious, but
it is interesting to note the correlation. If all evo-
lutionary lines would only progress at the same pace,
or if we could discover causal relations between the
lines, it would facilitate the construction of phylogenies.
OOGENESIS
We have seen that in spermatogenesis the gymno-
sperms show a reduction series from the highly differ-
entiated motile sperms of cycads to the free male nuclei
No. 526] SEXUAL REPRODUCTION IN GYMNOSPERMS 599
of Pinus. Oogenesis does not cover so great a range,
for motile eggs are not found above the thallophytes.
In its most primitive condition, the archegonium of the
gymnosperms is more reduced than any found in pteri-
dophytes, for there is no neck canal cell. An egg with a
definite ventral canal cell, as in Ginkgo and Pinus, is the
most primitive condition found in gymnosperms. Be-
yond this there is the elimination of the wall between
the ventral canal nucleus and that of the egg, as in
cycads and many conifers, a natural step in the elimina-
tion of the ventral canal nucleus, and in Torreya, even
the nuclear division has probably failed to take place,
so that the central cell functions directly as an egg. A
still further reduction is found in Tumboa where the
incomplete septation of the female gametophyte results
in a failure to organize a definite egg; and finally, there
is a complete suppression of any septation whatever, so
that the egg is represented only by a nucleus with as
little organization of cytoplasm about it as can be found
in any angiosperm. Thus there has been a gradual re-
duction of the archegonium from a condition almost like
that of the pteridophytes to the most extreme condition
found in angiosperms.
Some might suggest that such reductions would have
their natural termination in the elimination of all sexu-
ality, with apogamy as the goal. In Gnetum Ule there
seem to be instances of apogamy. In the cases reported
as apogamy in Pinus there is the possibility of fertiliza-
tion by the ventral canal nucleus. Personally, I prefer
to regard apogamy as a specialized, unnatural phenom-
enon, and not as a condition toward which plants are
moving.
The behavior of the chromatin in the final stages of
both spermatogenesis and oogenesis in gymnosperms
seems to be unique. At the formation of the ventral
canal cell or ventral canal nucleus, the chromosomes are
very small, The ventral nucleus or cell soon disinte.
grates, but the chromosomes of the egg nucleus form a
spirem. From this point there is a period of develop-
600 THE AMERICAN NATURALIST [Vou. XLIV
ment for which we have no satisfactory account of the
chromatin. The coarse reticulum of the egg nucleus is
not chromatin, for most of it may remain after chro-
matin again becomes demonstrable. To say that the
chromatin becomes dissolved in the linin or takes the
form of coarse granules or nucleoli, which may or may
not be chromatin at all, hardly solves the difficulty. That
some of the so-called metaplasm has about the same
position as the latest recognizable stages of the spirem,
seems to be about all that can be said. It is certain that
chromatin has not yet been traced from the telophase
of the ventral canal cell mitosis to the resting egg
nucleus with any such certainty as in the pteridophytes
and angiosperms. The organization of the spirem from
the dubious contents of this nucleus has not been traced
in any satisfactory way. However, it is perfectly cer-
tain that a small and beautifully definite spirem finally
appears.
FERTILIZATION
To the cytologist, who is likely to attribute extreme -
importance to chromatin, these reduction series in the
formation of eggs and sperms are very important, since
the more there is eliminated from the structures taking
part in fertilization, the more accurately can we deter-
mine what is essential and what only accessory.
Fertilization has been studied more thoroughly in
Pinus than in any other gymnosperm. Here each arche-
gonium has its own archegonial chamber and the pollen
tube entering it necessarily discharges its contents into
the one egg, the two male nuclei, together with the stalk
and tube nuclei and also more or less cytoplasm and
starch all entering the egg. One of the male nuclei comes
into contact with the egg nucleus and the nuclear mem-
branes at the point of contact break down, so that the
chromatin of the two nuclei becomes surrounded by the
membrane of the egg nucleus. A spirem is formed from
the chromatin network of each of the sex nuclei and each
spirem segments into 12 chromosomes, so that there are
twenty-four chromosomes. These do not fuse with one
No. 526] SEXUAL REPRODUCTION IN GYMNOSPERMS 601
another, but become so mixed that the male and female
chromosomes can not be distinguished. Each chromo-
some then splits and during the completion of the mi-
tosis twenty-four chromosomes go to each pole to form
the first two nuclei of the sporophyte generation. Con-
sequently, during this process which we call fertilization,
there has been no blending of the chromatin contributed
by the two parents. Whether a real blending takes
place as the two groups of chromosomes pass from the
telophase of the first mitosis into the resting reticula of
the daughter nuclei, is still undetermined. Personally,
I am inclined to think that there is no blending, either
at this early stage or later, but rather, that the chro-
matin contributions remain distinct throughout the life
history. Whether there is, during the synapsis stage of
the reduction division, sufficient fusion to impair the
identity of the individual chromosomes, still remains to
be demonstrated.
Although the chromosomes of the two groups become
so mixed that they can not be distinguished, the well-
known mechanism of mitosis makes it certain that one
half of each chromosome contributed by the two parents
will reach each of the two daughter nuclei resulting from
the first division of the fertilized egg. The same mech-
anism of mitosis makes it very probable that this equal
representation of the two parents will continue through-
out the life history of the plant.
In all the genera which have been studied, more or less
cytoplasm enters the egg with the male nucleus. In the
cycads the entire sperm enters the egg and the cilia may
continue to move after the sperm is within the cytoplasm
of the egg, but the nucleus of the sperm soon slips out
from the cytoplasmic sheath and advances toward the
egg nucleus, leaving most or all of the cytoplasm in the
upper part of the egg. In other forms, like Torreya,
Juniperus and Taxodium the cytoplasm of the male cell
surrounds the fusion nucleus and takes part in the forma-
tion of the embryo, but in most genera, no such cyto-
602 THE AMERICAN NATURALIST {[Vou. XLIV
plasm is visible and the embryo is formed from a rather
small portion of the basal region of the egg, quite remote
from whatever cytoplasm may have entered the egg with
_the male nucleus.
On such evidence we could not claim, logically, that
cytoplasm does not play an essential part in inheritance,
for the egg at its first segmentation contains cytoplasm
brought in with the male nucleus, but we believe that
the series which we traced in spermatogenesis presages
the final elimination of any cytoplasm as a part of the
male contribution, and the series could be carried into
the angiosperms, where, in some cases, the male contri-
butes only a nucleus without any cytoplasm.
In nearly all the gymnosperms the immediate response
to the stimulus of fertilization is a series of nuclear divi-
sions which follow each other in such rapid succession
that no cell walls are formed between the nuclei. The
divisions are simultaneous, probably because the nuclei
are in a common mass of cytoplasm exposed to the same
conditions. In the large eggs of the cycads, the free
' nuclear divisions continue until there may be more than
a thousand nuclei, but in forms with smaller eggs, the
period of free nuclear division is correspondingly re-
duced, so that we can select a series of genera which
show more than a thousand free nuclei, 256 nuclei, then
32, 16, 8, 4 and finally no free nuclear division at all, the
first nuclear division of the fertilized egg being followed
by the formation of a wall between the daughter nuclei.
These early stages in the gymnosperm sporophyte are
remarkably like the early stages of the gametophyte,
which also has a prolonged period of free nuclear divi-
sion before walls begin to be formed, but the conditions
are also very similar. The most striking difference be-
tween the sporophyte and gametophyte in these early
stages is that during mitosis one shows twice as many
chromosomes as the other. Very soon, of course, the
two generations become very dissimilar. It is worth
recalling, in this connection, that in some alge, like
No. 526] SEXUAL REPRODUCTION IN GYMNOSPERMS 603
Dictyota and Polysiphonia, the two generations remain
similar throughout the vegetative period, the only dis-
tinguishing feature being the number of chromosomes.
In conclusion, we believe that fertilization is a phe-
nomenon of fundamental importance, and that future
investigation dealing especially with the differences be-
tween the various chromosomes, differences which may
be only fortuitous but which may be constant and im-
portant, may throw light upon the problems of variation
and heredity. That the fusion of gametes always gives
rise to a sporophytie generation and necessitates a reduc-
tion of chromosomes somewhere in the life history is
not so speculative and the claim is readily admitted for
plants above the thallophytes. We believe that it holds
even for thallophytes.
In the simplest bryophytes, alternation is already too
thoroughly established to throw any light upon the origin
of the phenomenon, and the same may well be said of
alge like Dictyota, Cutleria and Polysiphonia. We be-
lieve that even where the first division of the zygote or
fertilized egg shows the reduction division, as in Coleo-
chete, there is a true alternation of generations, although
the sporophyte generation is very short. The test of a
sporophyte is not its longevity. The fertilized egg of
a lily is the first cell of the sporophyte, whether it ever
divides at all. Consequently, we regard the zygospore
of Ulothrix or Spirogyra and the fertilized egg of
Vaucheria or Cdogonium as sporophytic structures,
even if the first division of the zygote should be meiotic,
as seems probable. From such a simple beginning, we
believe that the more complex sporophytes with more
conspicuous alternation have been developed. The
gymnosperms throw no light upon the origin of alterna-
tion, but show suggestive stages in the reduction of the
gametophytes. They also afford an admirable field for
the study of some aspects of fertilization, but we can
hardly claim that all the problems of this complex phe-
nomenon would be solved with greatest certainty by the
study of cycads or pines.
NUCLEAR PHENOMENA OF SEXUAL REPRO-
DUCTION IN ANGIOSPERMS!
PROFESSOR D. M. MOTTIER
INDIANA UNIVERSITY
Waar constitutes sexual reproduction, fertilization or
fecundation is so variously set forth in botanical litera-
ture that one naturally approaches a discussion of this
subject with some timidity. Having been assigned the
group angiosperms, in which a definition of sexual phe-
nomena may be made more specific by concrete illustra-
tion, it seemed at the outset that a part of my task, at
least, was simpler than that of some of my colleagues
who take part in this section of our program; but a
moment’s thought convinced me that what might be
gained from this limitation of my field was probably
much less than the opportunities offered by the scope
and diversity of phenomena in groups of lower plants.
In the preparation of this paper, the writer has kept
clearly in mind the fact that the phenomena of sexual
reproduction implies explicitly that a special significance
is attached to the nucleus as in a large measure distinct
from any function, or rôle of the cytoplasm; consequently
he will deal first chiefly with nuclear behavior, leaving
a discussion of the relation of nucleus and cytoplasm to
be dealt with in a later paragraph.
Sexual reproduction in phanerogams implies the union
of especially developed cells known as gametes, and the
development of an individual plant from such union.
While in this process the union of the nuclei is held to
be more important, it is not inferred that the part taken
by the cytoplasm is unimportant, but the writer does
insist that the cytoplasm plays a secondary rôle in the
*A paper read by invitation before the Botanical Society of America,
Boston, December 30, 1909.
604 -
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 605
most important results of sexual reproduction, namely,
the transmission of parental characters. It will be
maintained also that the union of mere gametophytic
cells does not constitute fecundation, or a sexual process
in phanerogams, nor is parthenogenesis—if such really
exists in seed plants—to be confused with apogamy, nor
apogamy with the various sorts of vegetative propaga-
tion of the sporophyte. Lastly, it is likewise the duty
of the student of fecundation to consider the phenomena
of graft hybrids which have been reported in recent
literature, for such phenomena may have a profound
significance in the shaping of future theories of sex and
heredity, and on sex determination and control.
The problem of sexual reproduction in higher plants,
and in lower ones as well, is complicated by the existence
of two distinct phases, or individuals, in a life cycle,
namely, the gametophyte and sporophyte; for it is neces-
sary, in dealing with the rôle of the nucleus in sex, to
consider a complete life cycle. Now gametophyte and
sporophyte in phanerogams are fundamentally different
hereditarily, and this difference is due chiefly to the fact
that the former possess the haploid, or æ number, of
chromosomes, and the latter the diploid, or 2% number.
Whatever respect or disrespect one may have for the
“sacred” x and 2a number of chromosomes, the fact of
their importance in any theory of sex and heredity re-
mains the same, and must be taken into consideration.
It is, of course, quite familiar to all that the change from
sporophyte to gametophyte occurs in the formation of
the spores, and that this change consists in the reduction
of the number of chromosomes from the diploid, 22, to
the haploid, « number; that this reduction is accom-
plished during the first mitosis in the spore mother-cells,
this division of the nucleus being acknowledged as quali-
tative or differential. A detailed description of the
evolution and behavior of the chromosomes during the
tetrad divisions, and a discussion of controversies and
of the different views held in regard to this evolution,
or in regard to the differential character of any chromo-
606 THE AMERICAN NATURALIST [Vou. XLIV
some or set of chromosomes—are features which can not
find consideration within the limits of this paper. I
wish to state also that in the use of the expression,
sexual reproduction, I shall keep in mind primarily, and
for the sake of clearness, what will be called a complete
sexual angiosperm, hereditarily speaking, that is, one
with a complete life-cycle, embracing both sporophyte
and gametophyte. Such an individual arises from the
fusion of egg and sperm, each with the haploid number
of chromosomes. The product of this fusion must de-
velop into an adult sporophyte, capable of producing
functional micro- and mega-spores, each with the haploid
number of chromosomes. From this it will be seen that
the mere fusion of gametophytic cells or nuclei is not
necessarily regarded as a sexual process. It is to be
understood also that the writer does not consider it
imperative to stay within the confines of the foregoing
definition, for like nearly all general definitions, this is
made for convenience and for mene clearness in. the
general presentation.
No profounder statement has been made within the
past half century than when it was said that the union
of two sexual cells created a new individual—the indi-
vidual with just twice the number of chromosomes as
that possessed by either parent cell, namely, a sporo-
phyte; for is it not the sexual process that makes pos-
sible all those phenomena understood by the expression,
transmission of parental characters to offspring? And
I mean especially the transmission of characters of two
direct parents to each new generation. In this connec-
tion may we not ask also whether hereditary phenomena,
such as engage the attention of biologists at the present
day, exist among those simple plants in which sexual
reproduction does not occur? Is there such a thing as
phylogeny in plants that are without sex? The limits of
this paper prohibit an attempt at an answer to the last
two questions at this time. We shall have in mind then
those characteristics which are handed down from par-
ents to offspring. Some of these characters may mani-
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 607
fest themselves in the progeny with varying degrees of
intensity, or in such combinations that entirely new
marks or characters may appear; consequently char-
acters are spoken of as dominant, recessive, latent, ete.,
and it not infrequently happens that estimates are placed
upon absent characters. All of this implies that these
external marks of living things are the manifestations
of the activities of certain parts of the living substance,
which are in competition, or among which there is an
unceasing struggle. Attempts are also made to predict,
by means of mathematical formule—and with surprising
success in some cases—which of these forces or activities
will gain the upper hand and dominate, and which will
be secondary. Furthermore, sexual reproduction in
phanerogams always implies a something that we know
as maleness and femaleness, and this maleness and fe-
maleness are phenomena which distinctively characterize
the gametophytes. Maleness and femaleness may, in
certain cases, give a distinctive mark to the sporophyte,
as in diecious plants, if we admit that such a thing as
an absolutely dicecious sporophyte exists in angio-
sperms. But male and female marks are first mani-
fested in the sporophyte of most seed plants by the pro-
duction of the pollen and of the megaspores, which pro-
duction is, of course, a matter of heredity. In the forma-
tion of pollen, it is well known that it is the nucleus which
undergoes the important and complicated changes in
division; the cytoplasm, so far as present knowledge ex-
tends, is halved arbitrarily. The same is likewise true
in the development of the megaspores. In the case of
each spore mother-cell, a qualitative division takes place,
by which, as experimental evidence seems to indicate,
different intensities of maleness and femaleness pass
respectively to the several resulting cells. Both male
and female gametophytes with their developing gametes
grow under similar environmental conditions, namely,
that of a parasitic habit within living tissue. The
sperms of the pollen tube consist mainly of nuclei, with
scarcely any distinctive characteristics in the scanty
608 THE AMERICAN NATURALIST [Vou. XLIV
cytoplasm. These nuclei contain the haploid number
of chromosomes. In the development of the egg, the
same number of chromosomes is strictly preserved, no
matter what mitotic peculiarities may be observed in any
other cells of the embryo-sac, apart from the egg-appa-
ratus. The egg differs from the sperm in appearance
chiefly in the amount of cytoplasm present, but the cyto-
plasm of the one is similar to that of the other. Apart
from difference in shape, which is of no importance in
phanerogams, the sexual nuclei reveal identical chro-
matin structures at the time of union, for both are in the
resting, or non-mitotic state. Chromatin granules of
the sperm nucleus mingle with those of the egg. When
the nuclear membranes between the two contiguous nuclei
have disappeared, it is not possible to distinguish pa-
ternal from maternal chromatin. It is not seen that
_ chromatin particles of the sperm fuse or become paired
with those of the egg nucleus. The gamete nuclei do
not remain in any manner separate or distinguishable
from each other, as in certain lower plants and in some
animals, and one of the very interesting and important
problems from the standpoint of hereditary considera-
tions is the relation of male and female chromatin, dur-
ing the life of the sporophyte. A number of authors
have offered explanations of this relation based on ob-
servations made upon the first, or heterotypic, mitosis
in the spore mother-cells, i. e., at the end of the sporo-
phytic cycle. Strasburger (’05) and Gregoire (’05), to-
gether with a number of their more recent students,
maintain that the maternal and paternal homologous
chromatin parts become associated in pairs previous to
and during the synaptic balling up of the nuclear con-
tents in the first mitosis of the spore mother-cells. This
process, they assert, leads to the formation of two
spirems (one paternal and-one maternal) which become
united side by side, to form the double chromatin thread,
in which the homologous parental chromatin parts are
brought near to each other.
The writer (Mottier, ’07, 09) does not agree with this
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 609
view. From a careful and extended study of mitosis in
spore mother-cells of higher plants, he is convinced that,
confirming the observations of Farmer (’05) and others,
there is no development of maternal and paternal
spirems which unite laterally to form the double chro-
matin thread or spirem in the mitosis under considera-
tion, but that the sporophytic chromosomes are arranged
in a lineal series in the heterotypic spirem, and that
consequently the two members of each bivalent chromo-
some are brought side by side, in case such an arrange-
ment is attained by the two members of each bivalent,
by a folding, looping or lateral approximation of parts
of the spirem. In his own studies the writer is unable
to find any justification of the doctrine that maternal
and paternal chromatin is represented in definitely rec-
ognizable lumps designated by some observers as pro-
chromosomes. While I can not agree with the view
advocated by Strasburger and Gregoire, namely, the
presynaptic or synaptic union of two spirems (male and
female), because of my personal studies, I am also un-
able to accept their explanation upon the ground of
theoretical considerations. Let us return for a moment
to the fusion nucleus of the fecundated egg. It is per-
fectly clear that, soon after nuclear fusion, paternal chro-
matin elements, let us say, pangens, are indistinguish-
able from maternal elements. These pangens, assuming
always the individuality of the chromosomes and of the
pangens, correspond in form, size and staining qualities.
The nucleolus or nucleoli of the egg are also similar to
those brought in by the sperm, in case nucleoli are
demonstrable in the sperm nucleus. There is nothing
to lead one to believe that the parental pangens do not
mingle in the resting nucleus (i. e., not in mitotic activ-
ity). If there is a pairing of homologous parts, or ex-
change, inter-relation, or ‘‘ Wechselwirkung”’ of pangens,
or of any hereditary bearers, what reason is there to
believe that such should not take place soon after fecun-
dation, rather than at the close of the sporophytic
ontogeny, or the beginning of gametophytic develop-
610. THE AMERICAN NATURALIST [Vou XLIV
ment? If the nature and development of the sporophyte,
from the standpoint of its inherited characteristics, is
determined by what is transmitted to it by its parents,
how may these parental tendencies operate unless they
are intimately associated—unless some mutual relation,
or a ‘‘Wechselwirkung’’ of the entities representing
these tendencies, is in continuous activity? Further-
more, when the fusion nucleus of the fertilized egg in
angiosperms divides, the spirem separates by cross
segmentation into the 2x number of chromosomes, æ be-
ing male and x female. These sporophytic chromosomes
are arranged in lineal series, or end to end, to make the
spirem, which splits longitudinally. I do not believe
many cytologists will contend that the sporophytie
spirem is formed by the lateral coming together of male
and female spirems. If the parental chromosomes are
arranged tandem to form the sporophytie spirem, why
should they be arranged in any other manner to form
the heterotypic spirem?
Returning now to the fecundated egg, it is seen that
the fusion nucleus presents the same visible structure
as that of either gamete, with the exception that an addi-
tional nucleolus or nucleoli may sometimes be observed.
The essential demonstrable act in this fusion concerns
the nuclei; the behavior of the cytoplasm that may ac-
company the sperm nucleus is largely a matter of con-
jecture, for it is not possible to trace its behavior with
any degree of accuracy, either in the living state, or by
means of the indirect method of study. However, to
satisfy the demands of the most radical we may admit
that sperm cytoplasm unites with egg cytoplasm in the
act of fecundation. I have described in some detail the
structural union of the sexual nuclei; for in a later para-
graph will be discussed the relative significance of
nucleus and cytoplasm in sexual reproduction, and as
factors in the transmission of hereditary characters.
One male nucleus of the pollen-tube is concerned in
sexual reproduction as that term is understood in this
paper, but as the union of the second male nucleus with
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 611
the polar nuclei in a number of plants has been asso-
ciated with, if not actually regarded as, a sexual act, the
phenomenon will receive a brief mention. In 1897, the
writer (Mottier, ’97) called attention for the first time
to the fact that the second male nucleus applied itself
to one of the polar nuclei in Lilium Martagon, and
shortly after that date the actual union of this male
nucleus with the endosperm nucleus of the embryosac
was reported for various plants by different observers.
Guignard spoke of this nuclear union as a second fe-
cundation, hence arose the idea of ‘‘double fecundation’’
in phanerogams. The fusion of the two polar nuclei and
the second male nucleus resembles physically the real
sexual union, as do also nuclear fusions in ordinary
vegetative cells wherever such may occur. It recalls
a sexual act in subsequent behavior, for it is maintained
that endosperm thus arising is of a hybrid character,
and that this hybrid character is due to the hereditary
influence of the male nucleus. The hereditary influence
of the second male nucleus upon the endosperm we may
admit for the sake of argument, for whatever else this
phenomenon may signify, it certainly shows the greater
importance of the nucleus in the transmission of char-
acters. But, that this union of nuclei in the endosperm
cell is not a sexual process, as defined in a foregoing
paragraph, is seen in the fact that the endosperm is
merely a continuation of the female gametophyte, de-
veloped subsequent to fertilization of the egg, and for
the nourishment of the sporophyte, just as a fern pro-
thallium may continue its development, following the
fecundation of an egg and its subsequent development
into the embryo fern.
In a group of organisms in which a structure or fune-
tion is so universally present, the absence of the same
in any one or several of such organisms elicits at once
our attention, and, in this respect, apogamy and par-
thenogenesis become of special interest. Although
apogamy and parthenogenesis do not involve the sexual
act, yet an accurate and intimate knowledge of these
612 THE AMERICAN NATURALIST [Vor. XLIV
phenomena is likely to modify profoundly our views of
sexual reproduction, especially if a series of generations
of apogamously produced plants be compared with a
series of sexually produced individuals, of the same or
related species, in regard to the subject of variation,
individual vigor, manner of propagation, transmission
of certain characters, ete. The term apogamy is here
used to signify the development into an embryo of the
egg-cell possessing the double or 2” number of chromo-
somes without the union with a sperm nucleus from the
pollen-tube (somatic parthenogenesis of Winkler, par-
thenopogamy of Farmer and Digby). It is not deemed
desirable to connect the word parthenogenesis with such
a process, for a reproductive cell, although developed
morphologically as a gamete, is not so considered unless
it contain the reduced number of chromosomes. Accord-
ingly, the term parthenogenesis will be applied only to
the development into an embryo sporophyte of an egg
containing the x number of chromosomes.
In recent years several notable cases of apogamy
among phanerogams have been described, among which
may be mentioned Antennaria alpina by Juel (1900),
species of Alchimilla, especially of the group Eual-
chimilla by Murbeck and Strasburger (’04), Taraxacum
officinale by Juel, Wikstroemia, by Winkler, together
with several others from different families of plants.
In Antennaria alpina, for example, the tetrad divisions
do not take place in the megaspore mother-cell which
functions at once as the megaspore. Naturally this cell
contains the diploid number of chromosomes. From
this cell there develops an apparently normal embryo
sac, with the exception that the polar nuclei do not unite.
The cell which represents the egg develops without
fecundation into an embryo sporophyte. The process
in the other species mentioned is in the main similar to
that of Antennaria alpina, differing only in certain de-
tails, which may not be enumerated here. While, in
these apogomous species, an apparently normal gameto-
phyte develops, it may be very seriously questioned
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 613
whether such embryosacs, whose egg-cells contain the
these apogamous species, an apparently normal gameto-
phytic. However, progress in science is not accom-
plished by controversies and discussions of terminology.
The main thing which interests us here is the effect,
from an hereditary standpoint, that apogamy, of the
sort mentioned, has upon the species so affected. True
it is that such apogamous progeny have the characters
of both parents, male and female, but it is a remote
parentage. There is no new parent introduced with each
new generation, that is, each time a plant comes from a
seed, and it seems not improbable that the loss of cer-
tain very important reproductive functions may be ex-
pected in later generations of such plants. In reality
certain observed facts seem to bear out this suggestion,
as Strasburger found that, in some of the Eualchimillas,
degeneration took place in the pollen mother-cells before
the spores were fully formed. Whether apogamously de-
veloped plants will behave in a manner similar to those
propagated vegetatively, e. g., by cuttings, or as normal
sexually produced individuals, future research must de-
termine. Until the observations of the several observ-
ers have been confirmed by others, and until experimen-
tal cultural studies are made to ascertain the behavior
of apogamous plants along with those possessing sexual-
ity, speculation seems idle.
In regard to parthenogenesis as defined in a preceding
paragraph, this phenomenon is claimed to occur in cer-
tain species among rather widely separated families.
The best known instances are Thalictrum Fendleri, as
reported by Day (1896), Thalictrum purpurescens, by
Overton (1902, 1904) and Wikstremia indica, by Wink-
ler (1904, 1905). However, for Thalictrum purpures-
cens, Overton (1904, p. 278) expressly states that in some
cases no reduction in the number of chromosomes oc-
curs in the embryosac mother-cells, and that tetrads are
not formed, so that apogamy certainly occurs in this
species also. In regard to Wikstremia it may be added-
that the recent investigations of Strasburger upon this
614 THE AMERICAN NATURALIST [Vou. XLIV
plant and other Thymelacee, point rather towards
apogamy than parthenogenesis.
Even more perplexing to the student of sex and hered-
ity than apogamy or parthenogenesis are the phenomena
presented by what are known as graft hybrids. <A
number of seed plants of a hybrid nature are known
to botanical science, which have not arisen by means of
seed production, but presumably from the callus formed
at the juncture of the stock and scion in grafting. The
most noted of these is, of course, Cytisus Adami, which
is supposed to have arisen from Cytisus laburnum and
Cytisus purpureus as a graft hybrid. This problem,
which has held, in a large measure, the interest of biol-
ogists for about eighty years, seems now to be on a fair
way towards a solution, having as a starting point the
production of a graft hybrid experimentally. Hans
Winkler, as is well known, has produced a plant which,
in point of flower, fruit and foliage, seems to be a hybrid
between the common nightshade Solanum nigrum L. and
the tomato, Solanum lycopersicum L. of the King Hum-
bert yellow-fruited variety, by an ingenious method of
grafting in which the nightshade was used as the stock
and the tomato as the scion. Perhaps a very brief state-
ment of the process may not be out of place here.
Using the cleft method of union, Winkler grafted
vigorous shoots of the seedling tomato upon the stem of
the nightshade. As soon as union had taken place the
scion was cut off near its base in such a way that the
apical cut surface consisted partly of nightshade and
of tomato tissue. Of the adventive shoots arising
only those which sprang from along the line of union
of the two specifically different tissues were allowed
to grow. In one particular case fourteen of such sprouts
were removed and transplanted as cuttings. Of these
eight proved to be Solanum nigrum, five pure Sol-
anum lycopersicum, and one the hybrid in question.
This plant grew to flower and fruition, and as stated in
the foregoing, revealed hybrid characters in stem, leaf,
flower and fruit. This hybrid Winkler named Solanum
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 615
tubingense H. Wklr. (S. nigrum L. + S. lycopersicum
L., 1908). For a detailed description of the plant the
reader is referred to the original publication.! That the
conditions under which such a graft hybrid is produced
are very rarely fulfilled, is seen in the fact that from the
268 graftings made by Winkler in 1908, 3,000 adventi-
tious shoots were developed after decapitating the graft
in the manner described, and of these 3,000 the vast ma-
jority were specifically pure; five were chimeras, and
one the hybrid referred to. Now the all-absorbing ques-
tion for the cytologist is: By what means are parental
characters transmitted in cases of this sort? Of course
speculation is futile until the histological facts are
known, but, assuming that such shoots are real hybrids,
two guesses may be offered. There may have been (1)
a migration of nuclei from cell to cell and their subse-
quent fusion, as in certain fern prothallia developing
apogamous sporophytes, or (2) the hereditary transmis-
sion may have been accomplished by cytoplasmic union
between cells, or by some sort of enzyme action.
It is highly probable that these remarkable adventi-
tious shoots are not true hybrids, but mere chimeras.
n a personal communication, Dr. Winkler has very
kindly informed me that seeds of ‘‘ Solanum tubingense’’
produced pure nightshades (Solanum nigrum), and
those of ‘‘Solanum proteus’’ pure tomatoes (Solanum
lycopersicum).
The fact that seeds of ‘ Solanum tubingense’’ pro-
duced pure nightshades seems to be conclusive evidence
that the structure in question is not a hybrid, but merely
a remarkable chimera. Strasburger (’09) has just pub-
lished the results of a histological study of the tissues
formed at the juncture of stock and scion in grafts of
Solanum nigrum and Solanum lycopersicum, and he re-
ports that neither nuclear migrations from one vegeta-
tive cell to the other nor nuclear fusions in any of these
cells were observed. These results are in accord with
the same author’s cytological studies on other supposed
1 Ber. d. Deutsch. Bot. Geselisch., 26a: 595—608, 1908.
616 THE AMERICAN NATURALIST [Vou. XLIV
graft-hybrids. Winkler’s histological studies on ‘‘Sola-
num tubingense’’ have not yet been made public, but all
the facts thus far seem to indicate that so-called graft-
hybrids, including Laburnum Adami, the Bizzarrias and
those of Mespilus, ete., are only vegetable chimeras.
At the juncture of stock and scion in grafts, especially
in the case of those that produce adventitious shoots of
such remarkable character, there is a cell-complex formed
of the vegetative cells of two specific individuals, and
the specifically different cells may be regarded as being
so intermingled and reacting upon each other in such
a manner as to produce adventitious shoots of an almost
exact hybrid character in so far as vegetative marks are
concerned. In the case of Winkler’s ‘‘ Solanum tubin-
gense,’’ whose seeds gave only pure nightshades, it is
clear that both egg and pollen were descended from pure
nightshade cells, as the nightshade and the tomato do
not cross.
Although the problem of the so-called graft hybrids
can not be regarded as definitely settled, yet nearly all
the facts go to strengthen the view that hybrids are
formed only by the union of cells and nuclei sexually
differentiated, and that fecundation and the transmis-
sion of characters are not accomplished by the proto-
plasm in general, nor by the action of an enzyme, nor
is it the expression of metabolism, but by the union of
specific material entities in the sexual nuclei.
Although the concensus of opinion among biologists
attributes to the nucleus by far the most important réle
in the process of sexual reproduction in its fullest sig-
nificance, yet there is still some difference of opinion in
regard to the relative functions of nucleus and cytoplasm
in imparting the stimulus to growth and cell division,
and in the transmission of parental characters—the two
chief constellations of phenomena following the sexual
act.
To arrive at any satisfactory conclusion in the light
of existing literature, a careful analysis of cell structure
and of the functions more directly concerned is neces-
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 617
sary, both from the standpoint of phylogeny and from
that of the individual, or individuals concerned. Careful
investigations of recent years upon the cells of certain
lower plants seem to justify the opinion that the more
original or primary protoplasm is to be conceived as be-
ing entirely without organized nuclei, possessing uni-
formly in all parts its formative and nutritive functions.
Then there gradually came about, phylogenetically speak-
ing, a separation of the constructive, nutritive—and may
we also say—directive functions in this substratum, those
parts of the plasm having formative activities being the
first differentiated bearers of hereditary characteristics.
These particles or granules may have remained for a long
time distributed in the general plasmic mass, just as we
find in certain existing Cyanophycee and bacteria
‘“chromatin bodies’’ distributed throughout the cell
rather than collected in a typical nucleus. The next
step in the evolution of more differentiated protoplasm
occurred when the formative parts, be they known as
chromatin bodies, or what not, became separated from
the surrounding plasm by a membrane, or,in other words,
the creation of nucleus as distinct from cytoplasm. In
the light of known facts no one, I think, will seriously
believe that among the lower plants the nucleus is as
highly differentiated as among seed plants, consequently
a larger number of functions must have been performed
by the various hereditary units, and a much simpler
method of nuclear division demanded. This view seems
well borne out by the simpler method of nuclear division
in certain lower plants and in cells of higher plants,
which have taken on a purely vegetative réle, and which
divide by the direct method or fragmentation. As soon,
however, as differentiation in the hereditary units in-
creased, a much greater complexity in the mechanism
of division followed, a conclusion to which the mitotic
phenomena in higher plants stand as incontestible testi-
mony. On the other hand, we do not mean to imply
that progressive differentiation was confined to the
nucleus alone, for the cytoplasm of higher plants reveals
618 THE AMERICAN NATURALIST (Vou. XLIV
evidence of unmistakable differentiation. I do not allude
to the alleged hereditary substance, chondrosomes, to be
mentioned beyond, but merely to such differentiation as
spindle fibers, which in many higher plants are almost
wholly of cytoplasmic origin. As is well known, Stras-
burger has endeavored to make things clearer by apply-
ing to such parts of the cytoplasm as spindle fibers cen-
trosomes, centrospheres and the plasma membrane of
the cell, the term kinoplasm, attributing to this substance
certain activities. The researches of Noll upon marine
alge indicate with a very high degree of probability that
the plasma membrane is the part of the protoplasm which
takes a leading part in responding to external stimuli.
The doctrine that an enucleated cell can not do any con-
structive work, as, for example, forming a cellulose wall,
has become so generally accepted that the same has
found its way into general reference works. This doc-
trine has in recent years been disputed, but so far as I
am aware it has not been satisfactorily disproved. I
shall not bring into this category such cytoplasmic dif-
ferentiations as chloroplasts and other plastids, but
enough has been said to indicate that the cytoplasm as
well as the nucleus is a differentiated body, which means
a diversity of functions or activities. Now, although
cytoplasm and nucleus have certain functions that seem
in a large measure independent, yet the interrelation of
these two parts of the cell is such that neither can exist
and function to any great extent without the other. No
one has up to the present time been able to isolate a
nucleus and keep it alive any length of time apart from
living cytoplasm. Whatever the nucleus does, it must
do in connection with living cytoplasm. The cytoplasm
is in a sense the special environment of the nucleus, and
it is in this environment that the nucleus must exist and
function. It is also reasonable to believe that, in certain
functions of the nucleus, the cytoplasm acts largely as an
environmental factor. It is, however, an environment
so intimately connected with the nucleus that even a.
_ Momentary separation may prove fatal, for the skill of
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 619
the experimenter in this field is yet to be demonstrated.
On the other hand, while the cytoplasm may exist for
some time wholly apart from a nucleus, and although
during this separate existence the cytoplasm may re-
spond to certain stimuli, yet it can not do constructive
work—a phenomenon which seems to indicate roughly
the chief province of these two parts of the living cell.
In the light of the foregoing analysis, we may now
consider some results obtained by indirect methods, and
through certain experiments.
Since the declaration of O. Hertwig in 1875, that fe-
cundation consisted essentially in the union of an egg
and a sperm nucleus, this doctrine has received general
acceptance. Some observers maintain that this idea
places undue emphasis upon the importance of the
nucleus, and claim that the cytoplasm is almost of equal
significance. In a recent publication Meves (’08) de-
scribes in great detail rod or thread-like bodies in the
cells of the very young embryo of the chick, which he
designates as chondriosomes, and which he regards as
cytoplasmic bearers of hereditary characters. The same
author in 1904 described and figured similar rods and
threads as occurring abundantly in the tapetal cells of
Nymphea alba. In the tapetal cells of the anther of
Ribes Gordonianum, Tischler (’06, p. 573) calls attention
to slender rods of varying length, which he designates
as chromidial substance, stating that they came out of
the nucleus. The writer has examined many thousands
of tapetal cells from various plants, fixed and stained
in a manner quite similar to that used by Meves, but
no such bodies have been found as those figured by this
author. It is not my intention to discuss this phase of
the subject from the standpoint of zoological literature,
but it may be said that tapetal tissue is not the place that
a botanist would go to look for especially differentiated
hereditary substance. If hereditary substance, such as
Meves attributes to the cytoplasm of tapetal cells, really
exists, it seems very strange to a plant cytologist that
it ean not be demonstrated in spore mother-cells, where,
620 THE AMERICAN NATURALIST [Vou.XLIV
above all parts of the plant, protoplasmic structures are
most clearly brought out.
As stated in the foregoing, fecundation manifests two
constellations of phenomena, the transmission of par-
ental characters and the power of growth and division
of the egg. That these two categories are in a measure
distinct is amply attested by phenomena of common ob-
servation, and by experimental evidence. That various
sorts of environmental stimuli, from the sting of an
insect to the increased osmotic power of surrounding
water, will impart to living cells the power of growth
and division is well known. The sting of an insect, for
example, will stimulate growth and cell division in stem
and leaf, which results in a gall; the presence of a pollen
tube will induce an ovule to grow to mature size though
no embryo develops within it. In these and in other
similar cases, too numerous to mention, we have merely `
responses to external stimuli, for doubtless the pollen
tube may act as an external stimulus, and no one will
contend that these phenomena have to do with the trans-
mission of parental characters. From our standpoint
the phenomenon of artificial parthenogenesis merits
especial attention. When the egg-cells of certain marine
animals are stimulated to develop by external agencies
of whatever sort, it has become fashionable to speak of
the fact as fertilization, but whatever meaning be put
into the word fertilization, the phenomenon in question
is not fecundation or sexual reproduction. Even though
in every case the most sanguine expectations of the ex-
perimenter be realized, namely, the development into an
adult of an egg thus stimulated, the process would teach
us nothing more about sexual reproduction and the
transmission of parental characters than ordinary par-
thenogenesis. The fact that a larva having purely
maternal characters will develop from a sea-urchin egg
with which the sperm of a starfish had united, does not
show that hereditary characters are handed down by the
cytoplasm. If, on the contrary, the gastrula, showing
only maternal characters, which Godlewski (’06) reared
No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 621
from the union of an enucleated egg-fragment of the
sea-urchin and the sperm of a crinoid, could have de-
veloped into an adult, or even into the larval stage,
which still revealed only maternal characters, the cyto-
plasm might have regained some of its old-time prestige,
but even then it is doubtful whether that fact would have
wrested from the nucleus its monopoly as a transmitter
of parental characters.
In such cases as the embryo hybrid of sea-urchin and
starfish, mentioned in the foregoing paragraph, it seems
very probable indeed that the cytoplasm of the egg di-
rects and even controls the growth of the embryo for
a short time subsequent to fecundation, but it is very
improbable that the cytoplasm does more. Even in the
case of a complete fusion of the egg and sperm nuclei,
this and similar experiments seem to indicate’ only the
dominance of the egg nucleus over that of the strange
sperm. With the egg nucleus operating in its own
special environment, and attributing a directive or regu-
lative function to the cytoplasm, the result is what might
reasonably be expected. That the cytoplasm is differ-
entiated, and that it directs or regulates the formation
of certain parts of the embryo in some animals, is clearly
shown by the various interesting and important studies
of cell lineage carried out by Conklin (’05) and others.
Important and far-reaching as are these studies in con-
tributing to our knowledge of living protoplasm, they
do not teach us very much concerning the cytoplasm as
an heredity bearer, nor do I understand that the respec-
tive observers make such claims.
The stimulation of egg-cells to growth and division by
immersing them in water having different physical or
chemical properties than their normal surroundings, or
by injecting chemicals into the ovaries or ovules by
means of an hypodermic syringe, are lines of study that
are valuable and interesting in showing the response of
living cells and tissues to external stimuli, for it is the
business of the physiologist to know what cells can do
under any and all conditions; but that these experiments
622 THE AMERICAN NATURALIST [Vou. XLIV
have anything to do with sexual reproduction or in eluci-
dating the more fundamental principles in the evolution
of organisms connected with sexual reproduction, still
remains to be seen.
On the other hand, if one regards the elementary life
processes merely as the expression of metabolism, then
hereditary peculiarities are only the expression of metab-
olism. That which is inherited is for each organism
only that kind of metabolism peculiar to the organism.
Of course, the writer can not subscribe to this view.
Neither does he maintain that the cytoplasm takes no
important part in sexual reproduction. He has called
attention to the opinion that the stimulus to growth and
cell division which follows every sexual act fully accom-
plished, and which may be brought about apart from the
act of fecundation, has been confused with the main re-
sult of sexual reproduction, namely, the transmission of
parental characters. It is held that the present state
of our knowledge still maintains the doctrine that the
‘‘monopoly’’ of transmitting hereditary characters still
belongs to the nucleus, and that these hereditary parental
characters are represented in the nucleus by material
entities. It matters little whether we speak of these -
material representatives as pangens, or what not. The
opinion is expressed that the chief function of the cyto-
plasm, apart from purely nutritive activities, in its rela-
tion to the nucleus is directive or regulative in the sense
of being responsive to external stimuli. In so far as the
transmission of parental characters go, the cytoplasm
plays about the same rôle compared with the nucleus as
the environment does in the development of the individ-
ual organism.
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—— ’09. Meine Stellungnahme zur Frage der Propfbastarde. Ber. d.
Deutsch. Bot. Gesellsch., 27: 511-528, 1909.
Tischler, G., ’06. Ueber die Entwicklung des Pollens und der Tapeten-
zellen bei Ribes Hybriden. Jahrb. f. wiss. Bot., 42: 545-577, 190
Winkler, H., ’04. Ueber Parthenogenesis bei erien indica (L) ©. A.
Mey. Ber. d. Deutsch. Bot. Ge. src 22: 573-5 ;
706. Botanische Untersuchungen anes II., 7. Ueber
Parthenogenesis bei aise ‘adi (L) C. A. Mey. Ann. du
jardin botan. de Buitenzorg, 2 Ser., 5: 208-276, 1906.
— ’07. Ueber Prapfhaameta und pflanzliche Chimären. Ber. d. Deutsch.
at Gesellsch., 25: 668, 1907.
—— ’08. Solanum tubingense, ein echter Propfbastard zwischen Tomate
und Nachtschatten. Ber. d. Deutsch. Bot. Gesellsch., 26a: 595-608,
9
SHORTER ARTICLES AND DISCUSSION
STERILITY*
THE problem of sterility presents many points of interest to
the biologist, whether he be a clinician, breeder of plants or
animals or a pure biologist, both from a descriptive and an ex-
perimental aspect. By the physician, the failure of individuals to
produce children in marriage is designated by this name, although
the causes may be widely at variance in different cases. Thus,
the failure may be due to the impotence of the male, induced
by a variety of causes, such as congenital impotence, where sex
cells are not formed, although the organs themselves may be
apparently normal; or evident deformities may occur such as
the failure of one or both testes to deseend (eryptorchism) ;
again, impotence may be induced by disease, such as gonorrhcea,
syphilis and the like; or again, through presenile debility caused
by excessive activity of the organs concerned. On the other
hand, the failure to produce offspring may be due to the corre-
sponding impotence of the female, or it may result from wholly
secondary causes, such as the failure of the ovum to become fixed.
All of these cases are grouped, collectively, under the term ster-
ility. Very frequently a simple operation upon the uterus of
the female is sufficient to cause the ovum to become fixed, so that
subsequent ovulations, accompanied by fertilization, result in
offspring and the sterility disappears. With congenital sterility,
where no sex cells are formed, the case is obviously different,
for the condition there is permanent. Cases of congenital ste-
rility seem to be rare, although it is exceedingly difficult to
obtain concise data upon the subject. The impotence caused by
disease may, in time, disappear, especially if the ravages of the
disease have not destroyed the germ cells, as is often the case.
An impotence ascribed to psychical causes may rarely occur, but
concerning this factor, we have, obviously, little or no exact
evidence.
The sterility induced in crossing animals and plants belonging
to different varieties and species has long been known. The
Rebsgapgee Aa the fourth evening seminar of the Harpswell Laboratory,
August 2,
624
No. 526] SHORTER ARTICLES AND DISCUSSIONS 625
early hybridists of plants, Gärtner, Kölreuter, Nägeli, Gordon
and others, were familiar with the frequent failure of pollen,
placed upon the stigma of certain plants, to produce seed in the
ovules of that plant, and with the fact that even if seed is ob-
tained, it may not grow when planted. Kélreuter and Gartner
saw in sterility the criterion whereby species may be distin-
guished. If two forms bred together produced seed, and the
seed was capable of growing into perfect plants, the two forms
were considered as belonging to the same species. If, on the
other hand, no seed was produced, or if produced, this seed
was incapable of growth, the two forms were considered as be-
longing to distinct species. However, as Darwin points out,
these two workers were biased in their appreciation of sterility,
as a valid criterion for distinguishing species, for they themselves,
as have indeed all workers since them, described all degrees of
sterility under such circumstances, from slight deviations in form
of the hybrid plants, through a condition where the seed, although
formed, was shrivelled and incapable of producing the young
plant, to complete sterility, where no indication of even a pollen-
tube is seen in the style of the pistil. Obviously, the personal
equation of the experimenter will be a potent factor in deter-
mining whether there were two species, or a single one involved
in questionable cases, and the definiteness of the criterion is
largely detracted. To Darwin, who had carried out thousands
of crosses, the use of sterility as a distinguishing character for
species was an impossibility, and this fact was utilized by him in
combating the criticism urged against the theory of natural
selection, that it could not account for the origin of sterility by
assuming that it was a factor in isolating species.
It has been only within comparatively recent times that an
understanding has been reached as to what are the intimate re-
sults of sterility. It is true that Gärtner knew that the pollen
of many hybrids was shrivelled and functionless, but farther
than this, nothing was known of the condition of the spore-
bearing and gamete-bearing parts; for the rôle of the pollen-
tube, with the nuclei contained, and of the ovum in the ovary
was as yet unknown and the discovery of the alternation of gen-
erations in the higher plants had not been made. Not until
the reduction of the tetrads had been worked out was it possible
to understand the failure of the hybrid to produce seed, or, if |
seed were produced, to understand why abnormalities oceurred
in the young hybrid plants.
626 THE AMERICAN NATURALIST [Vou. XLIV
We have spoken thus far mainly of the work of botanists. for
the reason that little or nothing has been accomplished by zoolo-
gists until recently, which throws light upon the problem of ste-
rility. It was known by Aristotle that species would cross and
that the offspring varied from the parents in vigor and in other
characters. If the etymologists inform us correctly, the word
leopard, compounded of Leo, lion, and Pardos, panther, or tiger,
points to a belief among the Greeks, that the leopard was a
cross between the lion and tiger. The knowledge that captive
animals bred only rarely, many not at all, and that even when
mating occurred, the act was functionless and no offspring re-
sulted, although the animals were apparently normal, is nothing
of recent date. As to why offspring are not produced under
these conditions, we are wholly ignorant. No one has deter-
mined whether the male actually conveys the fertilizing fluid to
the female and if so, whether functional spermatozoa are present.
It is known that in some cases, confinement of wild animals
induces degeneration of the internal generative organs. Psychic
causes, too, are undoubtedly present, inhibiting the mating in-
stinct, but these factors are so subtile that they defy analysis.
The data are familiar to every keeper of zoological gardens, and
yet no attempt, to my knowledge, has been made to determine
any of the details involved.
Several cytologists have examined the gonads of hybrid animals
with a view to determining the condition of the sex cells. Thus,
Guyer studied the crossed pigeons from the cotes of Professor
C. O. Whitman at Chicago and found great abnormalities in the
secondary spermatocytes, such as clumping of the chromatin,
degeneracy of the cells as a whole, tri- and other abnormal mito-
ses. Spermatozoa were formed in many cases, but these cells
were obviously abnormal and pathologic. The gonads of the
mules obtained by crossing canaries and English goldfinches,
siskins, bullfinches, ete., are degenerate, and in some cases which
I have examined no trace of gonad could be found.
The cytology of the gonad of the mule obtained by crossing the
mare with the jackass has been examined by H. E. Jordan who
describes the testis as follows:
The seminiferous tubules are lined with Sertoli cells, spermatogonia
and a few primary spermatocytes in early stages. The nucleus of the
latter appears to be in the spireme phase of the contraction stage and
in process of regressive change. Mitoses are exceedingly rare and those
No. 526] SHORTER ARTICLES AND DISCUSSIONS 627
present are seen among the basal cells. Nothing corresponding to a
secondary spermatocyte or a spermatid can be found, nor are sperma-
tozoa anywhere present, either in the seminiferous tubules or the epi-
didymis. The absence of spermatozoa explains why mules are infertile
inter se, as also the fact that no issue results from a cross between a
female horse and a male mule (the cross between a female mule and a
stallion is known to have resulted in offspring) .*
Aside from this study, and that of Guyer ic of above,
I know of no examination which has been made of the gonads of
hybrid vertebrated animals. The conditions which I have found
in canaries resemble closely those found by Guyer, in pigeons.
The observations of Ancel and Bouin? on eryptorchid horses
resemble to quite an extent, those by Jordan upon the mule
testis.*
` Hybridization experiments with lower forms of animals throw
some light upon the behavior of the germ cells concerned in
fertilization. Moenkhaus found that he could cross Fundulus
and Menidia, two species of fishes, and obtain normal hybrids.
Owing to the differences in size of the chromosomes in the two
species, he was enabled to determine the fate of the chromosomes
of the egg and of those of the spermatozoon and it was possible
to follow them through the embryonic history, through the vari-
ous mitoses of segmentation and later. Here, the chromosomes
were in no way antagonistic and proceeded through the mitoses
side by side.
Balzer® performed a series of very interesting experiments
upon several species of echinoderms occurring in the Bay of
Naples. He used four species, Strongylocentrotus, Echinus,
Arbacia and Spherechinus, making reciprocal crosses. Crosses
between Strongylocentrotus, Echinus and Arbacia gave normal
fertilizations, with no loss of chromatin in the earlier segmenta-
tion anaphases, and the plutei exhibited normal skeletons, except
* Whitehead, R. H., 1908, ‘‘A Peculiar Case of Cryptorchism and its
Bearing upon the Problem of the Function of the Interstitial Cells of the
nice : ae pereje (Philadelphia, U. S. A.), Vol. 2, p. 177.
l et Bouin, 1903-4, Journ. de Physiol, et de Path., T. 6, Nr. 6, 7.
Also angen Baka T.. 137, Nr. 26: P. 138. Nre 2, 3, 4.
* See Schwalbe, E. (Hereees, “Die Marbo der Minsbidungen
des Menschen und der Tiere,’’ Ein Hand- und Lehrbuch, Dritter Theil:
Die Einzelmissbildungen
ë Balzer, F., 1909, «Ueber die Entwicklung der Echiniden-Bastarde mit
besonderer Herlihslabtirees des Chromatinverhaltnisse,’’ Zool. Anz., Bd.
?
628 THE AMERICAN NATURALIST [Vovu. XLIV
in one ease. With Spherechinus and Strongylocentrotus
several chromosomes were eliminated in the anaphase of the
first segmentation stage, which were excluded from the nucleus
of the resulting cells, when the nuclear walls were formed. Cor-
relative with this, the plutei showed abnormalities and the gen-
eral resemblance was to the maternal species. Apparently here
the case is different from that of Moenkhaus’s Fundulus-Menidia
hybrids, for the chromatin of the egg in part at least, is not
adapted to association with that of the eggs of the other
species. If this interpretation is correct, we may refer the ab-
normalities of the hybrid produced from the cross of Sphere-
chinus to the loss, during the segmentation stages, of chromo-
somes derived from the female. The analysis cannot be pushed
farther back, in this case, for we are unable to understand why
these chromosomes which are excluded from the reconstructed
nucleus are ‘‘incompatible’’ with those of the egg-nucleus.
Whatever the cause, it is probably similar to the agglutini-
zation of erythrocytes, spermatozoa, bacteria and other cells
in the fluids from other organisms or in artificial media. In
this connection, it is interesting to recall that Guyer and Jordan
found the abnormalities in the testes of hybrids appearing first
during the synapsis period, when the chromosomes from paternal
and maternal sources conjugate two-by-two, either end-to-end
or side-by-side (probably side-by-side in chordates, according to
the observations of Winiwarter). Recent study of spermato-
genesis and oogenesis points to the conclusion that the maternal
and paternal chromosomes remain distinct and more or less iso-
lated from one another in the primary germ cells, from the time
of fertilization until synapsis, and then for the first time are
they intimately associated into pairs, as Montgomery suggested
—a view which has been abundantly confirmed by Sutton, Ste-
vens, Wilson, and a number of others. Here, then, would it be
expected that incompatibilities, if ever present, would become
apparent. If the phenomenon is of the same category as agglu-
tinization, hemolysis and the like, it should be possible to render
the sex-cells of one animal immune to the lytic action of those
of other animals, on the principles of immunization and anti-
body development. In a case, however, where such a relation
appears much more clearly, it seems that the phenomena are not
of the same kind. I refer to the auto-immunity of Cynthia,
where the eggs of a given individual of Cynthia partita cannot
No. 526] SHORTER ARTICLES AND DISCUSSIONS 629
be fertilized by the spermatozoa of the same individual. Morgan
analyzed the phenomenon in the light of immunity and was un-
able to demonstrate a parallel between the Cynthia immunity
and that in anti-body formation.® However, the case described
by Morgan may not be equivalent to those of hybridization
experiments, such as we have described.
Concerning the relation of the chromosomes to fertilization
and subsequent condition of the embryo, Bataillon” derives cer-
tain evidence from his amphibian crosses for the conclusion that
the number of chromosomes in the two parent species involved in
the cross is of importance in determining the condition of the
embryo resulting. Thus, when the number of chromosomes in
the two species is the same, no embryo results, while crosses
between species with different numbers of chromosomes lead to
progeny. If this observation is true, it might be due to the
fact that mainly, or only those chromosomes which are in excess
of the number occurring in the species with smaller number of
chromosomes and which do not pair up in synapsis with the
chromosomes of that species, are functional in producing the
embryo. Under these conditions, we should expect that the
embryo would resemble the species with the greater number of
chromosomes. However, this does not follow, inasmuch as
Bataillon did not observe nuclear copulation, but rather a mode
of artificial parthenogenesis is supposed to occur, the male ele-
ment being wholly without effect in inducing fertilization and,
therefore, the progeny would resemble the maternal species.
In 1906, Emil Godlewski, Jr., succeeded in obtaining a few
hybrids between the sessile crinoid, Antedon g and Echinus 9,
thus involving two classes of echinoderms, the Echinoidea and
Crinoidea. The sperm exerted a marked inhibition of develop-
ment as a whole and the hybrids resembled the maternal Echi-
nus. This case is probably similar to the one described above
where non-compatibility is evident between egg and sperm nuclei
in fertilization. Godlewski did not examine the chromosomes
with a view to determining their condition in the cells of the
hybrids.
* Morgan, T. H., 1910, ‘‘ Eggs of Cynthia, Immune to their own Sperm,’’
a paper before the Society for Experimental Biology and Medicine, to be
published in full in the Journal of Experimental Zoology.
1 Bataillon, M. E., ‘‘Le substratum chromatique héréditaire et les com-
binaisons nucleaires dans les croisements chez les Amphibiens,’’ Comptes
Rendus, Paris, T. 147, f. 692.
630 THE AMERICAN NATURALIST [Vou. XLIV
Godlewski did not find it necessary to resort to artificial means
in causing the spermatozoon of Antedon to penetrate the egg of
Echinus, but by an ingenious method Loeb® was enabled to cause
the egg of a member of one phylum to be fertilized by the sperma-
tozoa from a member of a different phylum. Kupelweiser® after-
wards applied Loeb’s method to a cross between the mussel,
Mytilus 3, and the echinoderm, Echinus 9, the method involving
a subjection of the eggs to a hypertonic solution of sea-water, as
in artificial parthenogenesis. Bataillon’® believes that only arti-
ficial parthenogenesis is operative in this case, basing his con-
clusions partly upon analogous crosses in amphibians, where he
has crossed Triton ¢ with the toad Pelodytes 9, and observed
that no sperm asters formed and segmentation proceeded without
any participation on the part of the sperm nucleus.*? Of course
if Bataillon’s contention is correct, the case is of no interest in
the present connection, but if the two cases are not parallel,
Loeb has overcome what we may grossly term sterility, by arti-
ficial means, by modifying the osmotic pressure and the permea-
bility of the egg-membrane so that the spermatozoon of the
foreign species may enter. Sterility here then may be due to
purely mechanical factors. Yatsu has pointed out that the ©
failure to procure crosses between the frogs Rana sylvatica 2 and
Rana virescens J is due to the fact that the heads of the sperma-
tozoa of the latter are too large to enter the eggs of the former.
Here, again, a purely mechanical factor is involved.
While no experiments have been performed to my knowledge
to determine whether a kind of acclimatization may be induced
in hybrids, yet some experiments performed by botanists shed
some light upon this point. Giartner,’2 Wichura’*® and Niageli™
believed that fertility decreased in later generations, but
Naudin, C. C. Hurst: and others, including DeVries," believe
* Loeb, J., Roux’s Archiv, Bd. 26, Heft 3.
: PEER H., Roux’s Apehin, Bd. 27, S. 434.
* Bataillon, E., ‘‘ L’imprégnation hbthcoutins sans Amphimixie nucléaire
chez les PEE i et les Echinodermes (à propos du recent travail de H.
Kupelwieser),’’ Roux’s Archiv, Bd. 28, S. 43-48, 1909.
“ Bataillon, E., ‘‘Imprégnation et Fécondation,’’? Comptes Rendus, 11
Juin, 1906.
1 Gartner, 1849, ‘‘ Bastarderzeugung im Pflanzenreich.’’
* Wichura, M., 1865, ‘‘Die Bastardbefruchtung im Pflanzenreich.’’
“ Nägeli, C. v., 1866, ‘‘ Botanische Mittheilungen,’’ Sitz. ber. der Münch.
Akad. Wiss., 13 Jan., 1866.
* Naudin, Ch., 1869, ‘‘ Nouvelles recherches,’’? Nowvelles Archives du
No. 526] SHORTER ARTICLES AND DISCUSSIONS 631
that fertility increases, or, in other words the barrier, more or
less perfect, between hybridization of the species involved, is
gradually broken down. As Kerner! has shown, indeed, many
hybrid plants are more fertile than the parent species and this
is maintained and increased during future generations, so that
the hybrids have replaced the parent species. There is, then,
a basis for believing that a kind of acquired ‘‘congeniality’’
obtains, whereby the conjugating cells become more compatible,
whatever this may ultimately involve. An interesting case was
described by Gordon’® where Nicotiniana, Digitalis and other
hybrids are sterile inter se, but fertile with the parent forms.
_ In the cross between the dog and the wolf, sterility begins, not in
the earlier generations, but in later ones, according to the obser-
vations of Flourens, but as Darwin remarks, it is doubtful that
this is due to increasing sterility because of crossing, but rather
to confinement or, indeed, to inbreeding.
The students of plant cytology were the first to examine crit-
ically the structures concerned in reproduction in hybrids.
Girtner long ago observed the shrivelled pollen grains, as we
have said before, but that was before the modern cytological
methods came into use. Jančič”? has contributed widely to this
department of research. He observed that the number of pollen
grains decreased in certain hybrid plants and that in the several
species he examined, this numerical reduction occurred in ap-
proximate amounts to one fourth, one half or three fourths the
average number of grains. Moreover, cytological examination
of the anthers showed that many of the nuclei after reduction of
the tetrads were atrophied, and the conclusion is obvious that
herein lies the explanation of his numerical ratios mentioned
above; for in some crosses, three fourths of the nuclei destined
for the pollen (the daughter and granddaughter cells of the pollen
mother-cell), or, in other words, three of the four tetrads,
aborted, leaving but one to become pollen (hence the one fourth),
while in other cases, two of the tetrads disappeared (two
Muséum a’histoire naturelle, Paris.
* Hurst, C. C., 1900, Journ. Roy. Hortic. Soc., Vol. 24, p. 124.
" De Vries, H, 1903, ‘‘ Die Mutationstheorie,’’ Vol. 2, p. 66.
18 Kerner, A. von, ‘‘ Können aus Bastarden Arten werden?’’ Oesterr. Bot.
Zeit., Bd. 21, 1871.
» Gordon, é. A., 1862, Mem. Acad. Stanisl., p. 228.
» Jančič, A., ‘‘ Untersuchungen des Pollens hybrider Pflanzen,’’ Oesterr.
bot. Zeitschr., 1900, Nr. 1, 2, 3.
632 THE AMERICAN NATURALIST (VoL. XLIV
fourths), so that one-half of the normal number of pollen grains
appeared. Here, again, it is the period of synapsis or of con-
jugation of the maternal and paternal chromosomes (the stage
corresponding to the gametophyte, where the chromosomes are
reduced in number) where the effects of hybridization are
evident.
Juel’! has shown that the chromatin distribution in the nuclei
of hybrids is irregular, corresponding to the conditions in hybrid
animals described earlier in the present paper. The condition
of the chromosomes during actual synapsis is such that it is
impossible to observe their behavior directly and, doubtless, noth-
ing could be learned of the ultimate cause of the irregularities
through mere observation during these periods, even if the
chromosomes could be more clearly followed. In such cases, it
seems to me, we have fought the matter of sterility to its inner
keep, and until experimentation comes to our aid, we shall be
able to proceed no farther. ‘‘Uber die Art und Weise, wie die
Eizellen steril werden, haben wir keine erwahnenswerthen An-
gaben gefunden” (DeVries).
Several cytologists have taken advantage of the exhaustive
studies of DeVries upon hybrids of the primrose, Œnothera
lamarckiana, to study the cellular phenomena of crosses whose
general features are well known. Thus, Geerts?? has recently
studied the partial sterility and the development of the embryo-
sac of G@nothera and finds that there are no antipodal cells de-
veloped and that the endosperm forms from the pole cells.
Sterility, says Geerts, is a matter of irregularities in the reduc-
tion division and therefore his observations tally with those, both
plant and animal, spoken of above.
Gates** and Miss Lutz** have investigated the cytology of Gno-
thera crosses and of Drosera hybrids. Irregular distribution of
the chromosomes obtained in the reduction division and these
differences are correlated with the external characters of the
crosses.
*Juel, H. O., ‘‘Beitrige zur Kenntnis der Tetradentheilung,’’ Jahrb.
wiss. Bot., Ba. 35, 1900.
2 Geerts, J. M., ‘‘Récueil Trav. Bot. Néerl.,’’ T. 5, 1909.
* Gates, R. R., Bot. Gaz., Vols. 46 and 48 ; Science, Vols. 27 and 30;
Archiv fiir Zellforsch., Bd. 3, H. 4, 1908-09.
“Lutz, Annie M., Science, Vol. 29, 1909.
No.526] SHORTER ARTICLES AND DISCUSSIONS 633
Finally, Rosenberg’ has invaded this fascinating field and
studied the hybrid sundews exhaustively. The main results of
his observations are similar to those given above in the case of
the other workers. Rosenberg adopts the explanation of ‘‘Un-
vertriglichkeit’’ (incompatibility) for the behavior of the chro-
mosomes—a view which Tischler,?*° who speaks from much ex-
perience in the cytology of hybrids, believes to be inadequate, for
the reason that, as Rosenberg as well as he himself shows, there
are a few cases where typical embryo-sacs are developed and
indeed the anlage of the young sporophyte may be found. ‘‘Die
gewöhnliche Sterilitat nicht in einer Unvertraglichkeit der bei-
derelterlichen Chromosomen liegt.’’??
We are able to see, therefore, that sterility, as far as may be
judged from studies upon the germ cells which have been made
thus far, is a matter of the fundamental constitution of the
organism. It concerns the bearers of hereditary traits, the
chromosomes. All of the studies which have been made point to
the conclusion that whatever may be its nature, there is an
‘“incompatibility’’ existing between the chromosomes of indi-
viduals of different species or varieties. Tischler’s contention
seems to me to be ill-founded, for the cases where normal struc-
tures occur in the embryo-saes of these hybrid plants are exceed-
ingly few, and when we consider the observations of other
workers upon plant material, and of the animal cytologists we
find abundant reason to believe that the exceptions mentioned by
Tischler may be better explained in another way. Moreover,
e know nothing of the constitution of the nuclei of the cells
of the young sporophytes, with respect to the mingling of
maternal and paternal chromosomes. It may be, indeed, as
Gates has suggested, that a condition of apogamy may obtain.
Undoubtedly the next few years will see many points as yet
undetermined, brought into proper perspective and we shall be
able to give a more complete account of the rationale of sterility.
Max Morse.
= Rosenberg, O., ‘‘Cytologische und morphologische Studien an Drosera
longifolia by rotundifolia,’’ K. Vetenskaps Akad. Handl., Bd. 43, Nr. IL,
63 S. Stockholm.
* Tischler, G., Zeitschr. f. ind. Abstammungsl., Bd. 3, H. 3, 1910.
"Tischler, i c.
NOTES AND LITERATURE
NOTES ON ICHTHYOLOGY
AN elaborate and excellent monograph is the ‘‘Ichthyologia
Amurensis,’’ by Dr. Leo S. Berg, being a ‘‘Catalogue of the
Fishes of the Amur River,’’ entirely modern in its method, and
very accurate in its details. Unfortunately, most of this ad-
mirable volume is in Russian, without résumé in any modern
language. It is published by the Imperial Academy of Sciences
at St. Petersburg, volume 24.
Professor T. D. A. Cockerell, of the University of Colorado,
continues his very interesting and fruitful studies of the scales
of fishes. In the Proceedings of the Biological Society of Wash-
ington (1910), he discusses the scales of the Cyprinoid and
Clupeoid fishes. He shows that the American genera related to
Chondrostoma are but two in number, Orthodon and Acrocheilus.
The scales of the American species are less primitive than those
of the old-world Chondrostoma.
In the study of the scales of Leuciscus and Rutilus, Professor
Cockerell shows that none of the American species belong to
either of these two genera, and none of them to the genus Phoz-
inus. For the American species called Leuciscus, the name
Richardsonius of Girard should be adopted; and for the Amer-
ican species called Phoxinus the new subgeneriec name Margar-
iscus is suggested. The name Myloleucus of Cope is properly
adopted for the American species hitherto called Rutilus. A
new subgenus, Temeculina, is proposed for Richardsonius orcutti.
The Japanese species called Leuciscus are not related to the
European species, but approach more nearly to the American
forms, perhaps entering the genus Richardsonius. Mr. Cock-
erell shows that the genus Notemigonus is well separated from
the European genera Abramis and Blicca.
The scales of the herring-like fishes are also discussed. These
show relatively simple and primitive structure.
he scales of the Atherinoid fishes show qualities more or less
like those of the mackerels. In other papers published in the
Smithsonian Miscellaneous Collections, volume 56, Mr. Cockerell
discusses the scales of the African Mormyrid fishes and of the
African Characins.
634
No. 526] NOTES AND LITERATURE 635
In the Proceedings of the Royal Society of Victoria (1909),
Miss Ethel R. Morris and Miss Janet Raff discuss the structure
of the little lancelet of the coast of Victoria, which they call
Asymmetron bassanum. The generic name Epigonichthys of
Peters has priority.
In the Journal of the Royal Society of New South Wales, Vol.
XLI, Mr. H. C. Dannevig, of the Department of Fisheries, dis-
cusses the effects of the coastal winds of Australia on the abun-
dance of fish in inshore waters. He shows that the relative
abundance of many species in different places is due to the nature
of the winds.
In the Annals of the Carnegie Museum, Volume V, Dr. Charles
R. Eastman describes a new fossil shark, Helodus comptus, from
Meadville, Pa.
In the Annals and Magazine of Natural History, Series 8,
Vol. 4, Mr. C. Tate Regan describes a number of new species of
fishes, mostly eels, from the South Seas and Australia.
In the same journal, Mr. Regan discusses the three-spined
sticklebacks of the world. He finds those of the Atlantic coasts
of Europe and America and those of the Pacific coast alike,
including all the species of three-spined sticklebacks hitherto
described under the name of Gastrosteus aculeatus, with the
exception of G. algeriensis, which has a smaller number of ver-
tebre, 29 instead of 31 to 33. He also describes a species with a
slender snout, from Rome, under the name of Gastrosteus holo-
gymnus, and a new species, Gastrosteus sante-anne, from the
Santa Ana River in California. This he regards as distinct from
the naked specimens of Gastrosteus hitherto known as G. william-
soni, by the presence of 29 instead of 32 vertebre. The specific
distinction of G. sante-anne is very doubtful, but Mr. Regan is
doubtless correct in saying that mailed, half-mailed and naked
forms in Europe and America are the same species, those living
in the sea being fully mailed, those living in fresh water mostly
nake
In the same Annals, Mr. Regan discusses the caudal fin of
Elops and of other fishes. He finds the tail of Elops distinctly,
heterocereal, like that of some of the fossil forms of earlier
periods. He also shows that the tail of Fierasfer is not gephyro-
cereal. In its general structure, it is like that of related forms,
but the caudal fin has disappeared.
In the Proceedings of the Zoological Society of London for
636 THE AMERICAN NATURALIST [Vou. XLIV
1909, Mr. Regan discusses in detail the family of Anabantide.
In the Archives de Zoologie Experimentale, fifth series, volume
1 (1909), Dr. Louis Fage discusses in great detail the variations
in the red surmullet of Europe. He finds that Mullus surmu-
letus is a form of Mullus barbatus somewhat less developed, so
that the two species can not be maintained as distinct. If one
is to give the right value to the variants of the surmullet, it is
necessary to have not only a trinomial but a quadrinomial system
of naming.
In the Bulletin de la Société Philomathique, 1909, Dr. Jacques
Pellegrin discusses the minute catfish of the genus Vandellia.
In the Proceedings of the Seventh International Zoological
Congress, Mr. Regan discusses the origin of the Chimeroid fishes.
He regards them as derived from the same stock as the sharks,
but more primitive.
In the said Proceedings, Mr. Regan discusses very fully the
classification of the Teleostean fishes. It will be a long time
before any satisfactory grouping of these animals can be made,
but every analysis of this sort shows the importance of the prob-
lem, and the soundness of the American view, that a complete
analysis of these forms must be made before any satisfactory
synthesis is possible. To place groups together simply because
we don’t know how to separate them, does not form a classifica-
tion of any permanence. A new order, Malacichthyes, is made
for the genus Jcosteus, and another order, Chondrobrachii, for
Podateles. On the whole, this classification shows several points
of advancement over any previously proposed, but there is
plenty of room for doubt in regard to many of the adjustments.
n the ‘‘Scientifie Investigations of the Fishes of Ireland,’’
Volume 4, E. W. L. Holt and L. W. Byrne discuss the Chimeras
of the Irish coast. These are three in number, C. monstrosa,
C. affinis and C. mirabilis. C. plumbea and C. abbreviata are
identical with C. affinis. A new species of Rhinochimera, R.
atlantica, is described. Of this genus, only a single Japanese
species is hitherto known. ;
In the Quarterly Journal of Microscopical Science, volume 54
(1910), Professor J. Graham Kerr describes the development of
the alimentary canal in Lepidosiren and Protopterus.
In the Publications of the Department of State, the Interna-
tional Fisheries Commission (David Starr Jordan and Edward
Ernest Prince) have published the regulations, sixty-six in num-
No. 526] NOTES AND LITERATURE 637
ber, by which it is proposed to control the fisheries of the interna-
tional boundary waters.
In the Proceedings of the United States National Museum,
Dr. Jordan and William Francis Thompson deseribe a new spe-
cies of deep-water sculpin, Triglopsis ontariensis, from Lake
Ontario. The Lake Michigan form related to this, long since
named T'riglopsis stimpsoni, is also described and figured.
In the same Proceedings, Frank Walter Weymouth, of Stan-
ford University, describes a collection of fishes from Cameron,
Louisiana. One species, Leptocerdale longipinnis, is described
as new. The three related species of this family, Cerdalide, are
known from the west coast of Mexico.
In the ‘‘Smithsonian Report’’ for 1908, Dr. Theodore Gill dis-
cusses the variant forms of angler fishes, with figures of many
species. He shows that the name Lophiodes, Goode and Bean,
‘‘Oceanie Ichthyology,’’ p. 537, has priority over the name
Chirolophius. i
In the Proceedings of the Portland Society of Natural History,
Vol. II, William Converse Kendall gives a list of the fishes of
Labrador, as collected by the Bowdoin College Expedition of
1891. A check list of the species of Labrador contains seventy-
three names.
In the Bulletin of the Illinois State Laboratory of Natural
History, Professor Stephen A. Forbes gives a series of maps,
showing the distribution of the fishes of Illinois in the streams of
the state. The distribution of these fishes reflects, as Professor
Forbes says, in uniformity and relative monotony, the features
of the topography of the state.
In the Philippine Journal of Science, Vol. IV (1909), Mr.
Alvin Seale describes a large number of new species of fishes
from the Philippines, in addition to those named in the check
list of Jordan and Richardson, published at about the same time
in the same journal. Mr. Seale has had opportunities for
making studies of the Philippine species such as have fallen to
no other ichthyologist.
In the Bulletin of the Bureau of Fisheries, Vol. 28, are the
proceedings of the Fourth International Fisheries Congress, held
at Washington in September, 1908. Upwards of thirty papers
bearing on fisheries are contained in this series, covering in some
degree almost every matter of interest to fish eulturists.
Notable among these papers is one by Dr. Theodore Gill, on a
638 THE AMERICAN NATURALIST [Vou. XLIV
plea for exact observation of the habits of fishes as against undue
generalization.
Mr. L. F. Ayson discusses the introduction of American fishes
into New Zealand, an operation which has been thoroughly suc-
cessful. Most notable is the growth of the rainbow trout in the
lakes of the northern island. Anglers are restricted to thirty
pounds a day, and over twenty tons of trout have been taken
out.of two small lakes at Rotorua in one season. The rainbow
trout is frequently taken from ten to twenty pounds or more
in weight.
Mr. G. M. Dannevig discussess the success of the Norwegians
in the planting of the fry of codfish in depleted waters.
Three papers, by S. W. Downing, Frank N. Clark and Paul
Reighard, on the promotion of whitefish production in the Great
Lakes, are especially important and suggestive. It is shown that
with the adequate planting of whitefish eggs it would be possible
practically to capture all the adult fish, and the natural spawn-
ing of the fish could be made a matter of no importance. This
discussion looks forward to the time when the fishing season for
whitefish will be largely identical with the spawning season; that
is, in November, when the eggs of each fish thus caught will be
preserved and hatched, and the young fish placed in the open
water of the lakes. The whitefish ground is greater in Lake
Erie than in any other of our American lakes. The plant of
whitefish fry in Lake Erie now approaches one billion young
fish per year, and, in spite of the enormous fishing taking place
in that lake, the number of whitefish is increasing.
The following are the special recommendations of Mr. Reig-
hard, and these should receive the most careful consideration
from those interested:
1. It is recommended, as a result of the foregoing study, that
the output of whitefish fry be increased as rapidly as possible, as
affording the most certain means of increasing the whitefish
production.
2. That an intensive plant of at least one hundred fry per
pound of whitefish caught be made on depleted areas. (Lake
Ontario and the southern waters of Lake Michigan are in need
of especial attention.)
3. That a close season be observed during the breeding season
of the whitefish as at present, but only for such waters as are not
under federal control.
No. 526] NOTES AND LITERATURE 639
4. That commercial fishing with pound nets and seines be per-
mitted in the waters of the Great Lakes during the breeding sea-
son of the whitefish wherever the state or national authorities are
prepared to undertake to care for the spawn of the fish taken;
the fisherman to be under legal obligation to permit the use of
the fish taken by them for the purpose of spawn-taking.
5. It is suggested that central control of the fishing operations
of the Great Lakes is highly desirable. Whether this is possible
in American waters through federal control or through concerted
action of the states is a question that can not be discussed here.
A central control, under which fishing grounds should be leased
and fishermen licensed, would, if properly administered, reduce
the cost of fishing and make possible more extended artificial
propagation. The central authorities should have power to
modify the fishing regulations pending legislative action. Such
a system might be made self-supporting.
6. The need of more exact knowledge of the habits of the
whitefish and of all the conditions under which it lives is very
evident. In the interest of the fisheries these matters should be
subjects of investigations to be carried on under federal auspices,
with suitable equipment and for a long period of years.
In another paper, President Jordan discusses the work of the
International Fisheries Commission, outlining the proposed op-
erations of Great Britain and the United States. This commis-
sion at that time had just been appointed.
John I. Solomon discusses a process for preserving the pearl
oyster fisheries, and increasing the value of the yield of pearls.
To this important contribution was awarded the prize of $100,
by the New York Academy of Sciences.
Professor Shinnosuke Matsubara, of the Imperial Fisheries
Institute of Tokyo, discusses the variant forms of the goldfish
developed by Japanese artist breeders. These are illustrated by
colored plates. :
Professor Jacob Reighard, of the University of Michigan, gives
a most valuable account of the nests of the horned dace, and of
the methods by which the habits of fresh-water fishes can be
offectively studied.
Davip STARR JORDAN.
640 THE AMERICAN NATURALIST [Vou. XLIV
THE MAMMALS OF COLORADO
Colorado Mammals.'— About seven years ago I called on Mr. E.
R. Warren at Colorado Springs, and saw his collection of mam-
mals, then recently begun. It was a small affair, easily laid out
on the parlor table. Since then, Mr. Warren has labored un-
ceasingly, visiting many different parts of Colorado, and has
accumulated an immense series of skins. The collection soon out-
grew its original quarters, and is now housed in a special build-
ing, in numerous cabinets which are already overcrowded.
While mainly a Colorado collection, it includes many species
from other parts of the country, obtained in exchange. Mr.
Warren has not only collected all these materials for taxonomic
investigations, but has paid much attention to the habits of the
animals, and in particular has secured a splendid set of photo-
graphs showing them in their native haunts. The logical out-
come of all this excellent work, a book on Colorado mammals,
has just appeared. It contains descriptions of all the species
and subspecies known to inhabit the state, with numerous illus-
trations, showing the living animals and the skull of each genus.
It is so far technical that it contains exact descriptions and all
other details needed for precise classification and identification,
but each form is also discussed in a popular manner, often with
entertaining anecdotes. Heretofore the study of Colorado mam-
mals has seemed too difficult for any one not a specialist, but
with the aid of this book it is made easy for any intelligent per-
Son, or as easy as such a subject, from its nature, can be. The
only regret I have about the work is that there is not more of it:
I should have liked a chapter on fossil mammals (especially of
the later periods), and one on parasites of mammals.
Apart from my great pleasure in the book itself, I can not
other than regard the manner of its production as a good omen.
Mr. Warren has lately been appointed honorary curator of Col-
orado College Museum, but he is essentially an amateur, in the
best sense of that word. He resembles the numerous amateur
naturalists of England, who have done so much for science; like
them, he has labored for the love of the work, without recom-
pense, and has shouldered the expense of publication, heavy as
it must have been. The most modest of men, I fear he may
resent being called a benefactor, yet it would be hard to exag-
gerate the benefit to the community which might come from an
increase of the spirit he represents. T. D. A. CockERELL.
**¢ The Mammals of Colorado,’’ by E. R. Warren, G. P. Putnam’s Sons,
New York, 1910.
The Anatomicai Laboratory
of Charles H. Ward
189 West Avenue, Rochester, N. Y.
OUR HUMAN SKELETONS are selected specimens scientifically
prepared and mounted. They are undoubtedly the finest and strongest
skeletons obtainable, and are purchased by the leading Medical and
skeletons for demonstrating dislocations, muscular areas, anthropometric
landmarks, muscles, e
The mounting of the articulations permits movements as in life.
Strength and rigidity are secured by the use of a special bronze wire of
enormous tensile strength and great resistance to oxidation. Portability
and ease of demonstration are attained by ickeled steel clutch stand-
ard, which is a great protection as well.
These skeletons are shipped entirely set up, carefully wrapped, and
with detailed directions for unpacking and handling. Our Catalogue
gives further details.
OUR SKELETONS OF TYPES OF VERTEBRATES are large
specimens, principally of American species, mounted in characteristic
poses on polished mahogany pedestals, with nickel-plated brass standards.
We offer a type collection for schools and colleges.
ANATOMICAL MODELS
p, wre:
anatomical models in great variety. These have been purchased by many
Schools and Universities. The series includes complete torso, head, brain,
nervous system, greatly enlarged models of the sense organs, etc., of most
of which we have large half tones. These models pay no duty, no trans-
portation, no middlemen’s profits, but are sold direct, at very moderate
prices, and can be supplied promptly when needed.
We also make BIOLOGICAL MODELS of the forms commonly
dissected in the laboratory. Ti dels rey t complete dissections of
the various animals, greatly enlarged (frog 18 inches long, eto. ), mounted
upon ebonized pedestals, with detailed descriptive labels. Series includes
ANTHROPOLOGY AND ETHNOLOGY
The Finsch Life Masks of Aborigines, including those islanders recently acquired by the United
States. Casts of Skulls, Skeletons and Brain, of Prehistoric Man. Casts of prehistoric bone carvings
from the caves of France. Stone implements of the North American Indians.
RELIEF MAPS OF THE UNITED STATES, the Continents, Grand Cafion of the Colorado,
Yosemite Valley, eto., made in Washington, D. C., for the United States Geological Survey and others
by Howell (a former member of the Survey). The only authoritative relief maps made com-
mercially in America. They are light, strong (made of papier maché), beautifully colored and
l ed, and as low in price as “cheap ” maps. For catalogues, halftones of models, maps, eto., address
CHARLES H. WARD
189 West Avenue, Rochester, N. Y.
The American Naturalist
TON a 1867, Devoted to
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A Consideration of the “Species Plantarum” of Lin
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of Crypto Professor W. G. FARLO
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VOL. XLIV, NO. 527 ° NOVEMBER, 1910
THE
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CONTENTS
Page
Heredity of Skin Pigmentation in Man. KTR “ = ghee and
~ 641
CHARLES B. DAVENPORT -
The Color Sense of the sierra A Bee--Can Bees Permanent * Colors ? a
bs
.
LOVELL - 673
orter Articles and Discussion: The Arithmetic of the Product Moment mT
* Calculating the Coefficient of Correlation: Dr. J. ARTHUR HARRIS - 69
on sie doe Mammals, ea bs D. oe
- 700
IV. Notes and Literature: Schlosse
. D. A. COCKERE -
e Ophidian Genus Grayia: Professor T
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THE
AMERICAN NATURALIST
Voit. XLIV November, 1910 No. 527
HEREDITY OF SKIN PIGMENTATION IN MAN
GERTRUDE C. DAVENPORT anb CHARLES B. DAVENPORT
CARNEGIE INSTITUTION OF WASHINGTON, STATION FOR EXPERIMENTAL
EVOLUTION, COLD SPRING HARBOR,
P EEA T E E a T E A OU is be bbw 5 Ue 0 8
B. Anatomical Relations and Kinds of Skin Pigment.................
C. Heredity of Skin Pigment in Typical Caucasians..................
(o) DIMO C BOHA CMON L) osese eonen neko sdabes crak os ï
(d) Intermediate X Intermediate (Table IV) ..................
(e) Intermediate X Blond (Table V) ............ Witenes eae
Cy) intermediate X Brunct: (TADO Vi). ye. res ei ece es ae
(g) Comparisons and Conclusions (Tables VII, VIII). er ere
Heredity of Skin Pigmentation in Crosses between Whites and
Ne
z
T E D EE EARE E E sce bev E oar ees
; Teda or A eseo nar ORT owe ce PE Ea Reh
I: Both Patents are Albinos (Casos 1-8), boi... ccs oe See en's
1i Netthee Parent Alpine fii cn oie he ce Cie es sans seas
(a) Albinos in Caucasian Families with Admitted Consan-
guinity (Oases 4-6) n sero sia = cesses tee cn sAr wens
(b) Albinos in Families with Suspected Consanguinity
Ed
e Albinos in Caucasian Families with no Evidence of Con-
sanguinity (Cases 8-23) .......eseseseesrressisnereso
(d) Colored Families SA DR BO) os ink ewig bids n ieee
Tri. One Parent Albinie (Casos B0, 31) as o6 ce cenhie ewe sess ees
he D.G.V il
e D.G.V. Family
V. The Condition of Hair and Eye Color in the Pigmented
Parents of Albinos (Tables Dy hy AL) ee ees eS
Vii ee Origin and ‘‘Cause’’ of Albinism (Tables XII, XIIT)
642 THE AMERICAN NATURALIST [Vou.XLIV .
A. INTRODUCTION
In the modern discussions on heredity there are those
who, without undertaking experiments themselves, as-
sume an attitude of hostility to the work of the experi-
mental investigators of heredity and have taken a last
stand in the phenomena of inheritance of human skin
color. Pearson (1909), who has urged that the collection
of extensive statistics is a prerequisite of deductions in
the field of heredity, has actually published the non-
quantitative impressions of a medical correspondent in
the West Indies concerning the method of inheritance
of skin color in negro X white crosses and concludes that
‘‘in view of the opinion’? cited ‘‘the suggestion that skin
color ‘mendelizes’ should not be vaguely made.’’ He
thinks his correspondent’s ‘‘views’’ establish ‘‘the main
point’’ ‘‘that the segregation in the second generation
to pure white or black skins does not occur.’’ On the
other hand, a writer in the Mendel Journal, No. 1, has
also a correspondent in the zone of intermingling whose
observations indicate partial, if not complete, segrega-
tion. Altogether the subject seems to deserve a more
extended, less biased treatment.
B. ANATOMICAL RELATIONS AND KINDS OF
SKIN PIGMENT
The pigment of the skin, at least the melanie pigment
which alone concerns us here, has its basis in the fine
granules lying in the deeper layers of the stratum
mucosum of the skin. The granules themselves are of
mesodermal origin and the pigment cells—melanoblasts
—seem to penetrate from below into the mucosa. Ehr-
mann (1896, Taf. XI, Fig. 24; Taf. IX, Fig. 19) has fig-
ured these melanoblasts in sections of the skin, both of
brunets and of negroes. They are much the more abun-
dant in negroes. The anatomical facts are that black
skin pigment is made up of many discontinuous elements
—the pigment granules. But the mosaic is so fine that,
to the naked eye, the color is apparently uniform and a
. No. 527] SKIN PIGMENTATION IN MAN 643
unit. The anatomical differences between the skin of a
brunet and a blond suggest that the grades of color may
be due to more or fewer of the elements of the mosaic,
and that would seem to be a discontinuous variation;
but, on the other hand, since these granules increase in
size and number during melanogenesis the difference in
skin color between a negro, a mulatto, a brunet and a
blond may be merely a difference in the point at which
the essential melanogenetic process is stopped.
Besides the melanie pigment a yellow-red pigment is
often present in skins of all races. This pigment is
commonly considered a lipochrome and, in hair at least,
is quite different in structure from melanic pigment.
C. HEREDITY OF SKIN PIGMENT IN TYPICAL
CAUCASIANS
The data for the study of inheritance in ordinary skin
pigment of whites were obtained from two sets of in-
quiries. The first set was supplied chiefly by school
children on cards 127 mm. by 203 mm., which called also
for data on the form and color of hair and the color of
eyes. The second set was derived from the Family Rec-
ords filled out for over 300 families, largely by adult
persons, including many men in professional life, geneal-
ogists and students, as well as farmers and men of af-
fairs.
The directions as to use of terms were necessarily
brief. In the first set they ran as follows: ‘4. Natural
complexion or skin color. Use terms as follows: blond,
brunet, intermediate, yellowish-white, olive-yellow, dark
yellow-brown (dark olive), copper colored, chocolate,
sooty black, full black, three fourths black, one half black,
one fourth black.” I willingly grant that terms are poor
means of expressing degrees and quality of skin pig-
ment. Nevertheless, blond and brunet are understood
widely in the same sense and it was hoped that ‘‘inter-
mediate” would be freely used in doubtful cases. This
expectation was not fully justified, since of 1,275 off-
spring recorded only 513, or 40 per cent. of all, were re- _
644 THE AMERICAN NATURALIST [ Vou. XLIV
corded as of ‘‘intermediate’’ color, while 460, or 36 per
cent., were given as blond and 302, or 24 per cent., as
brunet. In the ‘‘ Family Records’’ the nomenclature sug-
gested was: ‘‘Complexion or skin color: f (fair), i (inter-
mediate), br (brunet), d.br (dark brown),’’ ete. The
returns in the family records are for 1,098 children, of
whom 326, or about 29.5 per cent., are given as of ‘‘inter-
mediate’’ color; 635, or 58 per cent., as fair, and 137, or
about 12.5 per cent., as brunet. Evidently ‘‘blond’’ is
used in a more restricted sense than ‘‘fair’’ by the pop-
- ulation who filled out the blanks in question. All records
together are of 2,394 children. Of these there are 843 in-
termediates, or 35.2 per cent., 1,129 ‘‘blond’’ or ‘‘fair,”’
or 47.2 per cent.; and 422 ‘‘brunet,’’ or 17.6 per cent.
We thus see that only a little over one third of the chil-
dren are recorded as having an intermediate skin color,
while to nearly half are assigned the term ‘‘blond’’ or
‘‘fair.’’ The ‘‘brunets’’ are a relatively small propor-
tion of all children in the families under consideration.
‘Blond’? and ‘‘fair’’ have certainly been used too
broadly and this must affect somewhat the clearness of
our results. However, taking the returns as they come,
we shall be able to deduce certain conclusions of im-
portance.
In the following tables we have entered the grand-
parental data as given. We have, however, not used in
the statistics the grandparents as parents, not only be-
cause in that case only a single child of the family is
known, but especially, because the order of accuracy of
the grandparental data is, on the whole, inferior to that
of the parents and children. By and large, the grand-
parental data are highly suggestive, but exceptional cases
must be lightly weighted.
(a) Blond X Blond (Tables Ia, Is).—From_ two
‘‘blond’”’ or ‘‘fair’’ parents 526 children were altogether
recorded, of which 472, or 89.7 per cent., were ‘‘blond,’’
40, or 7.6 per cent., were ‘‘intermediate,’’ and 14, or 2.7
per cent., were ‘‘brunet.’? Owing to the fact that the
number of brunets given is very small and because it
No. 527] SKIN PIGMENTATION IN MAN 645
TABLE Ia
COMPLEXION: BLOND X BLON
Children. |
Family Name. —— M. | ; MM. MF. FM. FF.
Blond. | Inter. | Brun. |
Bry. 3 1 BEA EoD bl br bl bl
Bug. 2 BL R bl bl i bl
Cal. 4 bl b —— —— — ——
Cap. 1 1 bl b i i i i
Car. 3 2 bl b bl a br
Cla. 1 bl b bl bl i bl
Deg. 2 bl b —- i br bl
Edw 2 1 bl b -—— | a — =
Eli. 1 bl b br | bl br bl
Fay. 2 bl b bl bl br bl
Fir. 4 bl b i bl bl i
Fou. 1 bl b i i bl i
Fue. 3 bl b bl bl bl bl
Gra. 1 1 bl b bl i i bl
Hal.—A 2 2 bl bi br i bl bl
Hed.—D 6 bl - b bl bl bl bl
How.—C 6 1 bl: b bl bl bl bl
Ker. 3 1 bl b bl bl i bl
Klo. 4 bl b bl bl == bl
Koo 1 1 bl bi bl bl bl bl
Kra 3 bl b bl bl bl bl
Lav. 3 bl b bl bl bl bl
Len. 6 bl b br br br br
Lit.—B 3 bl b bl bl bl i
c 2 bl b bl — bl bl
McG 7 1 bl bl bl bl bl
Mye 4 bl bl bl bl bl
Pad. 5 bl i bl os =-
Pla. 6 bl bl bl bl bl
Reg. 6 bl bl i bl bl
Sha. 6 bl bl bl i bl
Sim, Bui 1 bl bl bl bl —
Ste.—F 2 bl bl bl bl bl
Ste.—G 1 1 bl br bl br —
Sto.—D 2 bl bi bl bl i br
Sto.—E 3 bl bl i i i i
Str.—A 5 bl bl i bl bl i
Str.—E 2 bl bl bl bl i
Totals (135); 121 10 4 |
38 families.
seemed likely that the rule established for hair color
would hold here (namely, that two light parents have no
dark children), I asked for further details from all fam-
ilies returning dark children of two blond parents.
Only two replies were received. In the case of a family
returning two brunets and four blonds from two blond
parents the new record gave the father as brunet instead
of blond. In the case of the second family said to con-
Pa
[Vou. XLIV
THE AMERICAN NATURALIST
646
TABLE IB
Far X FAIR
COMPLEXION:
| 3 1 Bee ge | |== |= |m Toksika kekakak kal- hahaaha EE al cry a a Le
| z Site ies ty Malte | [eee | a BB | ete ee ee eee Bete | | See ere see Se se ton ES tee ee te cet te te ce cee tee |
|
| = Ho H H tee o | te | tet e Ekek hekeheke bakisha kiaka hakali heka kaka hahai: kekakak -keL ETES
= w | ee te | |an on | BE wee eee |e Ba ee Be t S tet | 55 |
K tiahia “Sie ove. Wind aa GRA Spt. Sot. bid Aa Sein Ga See: Ane Sp Ang RON ek nal Ale Week Ma “Gay A Sie Re A A A N gd Ws a tds es t u
Sa JERE SSN E a A E ee ee Se oo |
g
a
g
g p
k 8 a a é vá vä rm — — ee rt
3E
fa
3 | |
E m m a O A O oD S m A m m A -N x Tlavey ai — +
a Oe a a a TEEST FEFEFE
= | €8S Sn BSSCLSESESSss Bas FRATE č KKE SBS PFEF e
EEr e E EEEE EET TAA Be
(i ‘
No. 527] SKIN PIGMENTATION IN MAN 647
| Children. | | | |
Family Name. | M. F. MM. MF. FM. | FF.
| Fair Inter. | Brun. | |
Row 8 tht fap Poot
Rud. E ER presoj £ Er r
Sch. | 10 > EUN eA o AT RE 2 feded
Sco.—2 BERN: s E O > Becht f f
She.—2 3 R eee 5 fe f ees eS
Shi.—1 3 St oot f i pele a
Sim. 4 ' Gare eee | br f Eset oe i
Smi.—1 es 1 Pee beac 3 i i Ha] i
Spa. Le 4 1 + ends ane © br f f | —
Str.—2 ‘eae 2 je ae a i f : ieee mee |
Sve. DR: Piss yee br f tea Gees |
Tau.—2 3 1 ang (pet 2 f — o ad
Tud.—1 3 f f f A O BRS
Vel. 9 1 f f f GP at
Ver. 5 f f f Ee ES N
Wan. 3 f f i Pes sO oe
War.—1 3 1 f f br Ej be br
Wes. 4 f f br Gees Pee eee eee i
Wha.—1 9 f f ed ol a See
Whi.—1 3 f f Pee le Poor £
Win. 7 f f fj fo) — | —
Wof 7 f f See Se oe
Totals (378)| 348 25 5 | | |
77 families.
sist of two blond, one intermediate and one brunet off-
spring, the new record gave the mother as intermediate
instead of blond, and the brunet child as light brunet or
intermediate, but somewhat darker than the mother.
These two families and a third (which is inaccessible)
comprising five blonds and four brunets, were therefore
struck out from the blond X blond table, leaving: only
four brunets, or about 3 per cent., among the 135 off-
spring, recorded in Table Ia. Tables Ia and Is give 9
brunets among 513 children, or 1.75 per cent. Keeping
in mind the probability of occasional blunders on the
part of the recorders, it seems doubtful if these nine
cases are properly included. The conclusion seems
justified that when both parents have blond complexion
or fair skin all of their children will have a similar fair
skin.
(b) Brunet X Blond (fair) (Table IL).—The off-
spring of dark by light skin color is of importance be-
cause it should throw additional light on the question of
dominance, if any. The families of two such parents are
648 THE AMERICAN NATURALIST [ Vou. XLIV
+
TABLE II
COMPLEXION: BLOND X BRUNET
5 = d 3 = g
Family Name. g k 2 M. | F. |MM.| MF. | FM.| FF. 8 S g
a} a] a a4 8h a
d. 10 br | bl | br ilt. blo | bl bl
Bex.—1 3 2 ore es f f i
Bin.—1 Trei 1 f | br} br f br br
Boh —2 2 Po pep et f f br i
Boy.—1 4j 2 1 fror oe f f f
Bra.—3 5 3 i be.) DE be br br br
Bro.—C oy oe Or Or pe br br i
Bro.—5 5} 2 b fj;—| — -— —
Bul. br | bl | bl br bl l 2
Bur.—2 $11 Ch pele f br br
Byn.—1 1 1 b |S ae. f f f
Car.—B br | bl | br i bl i 1 4
Car.—1 2139 ne i i br f f
Cas. 2 br | bl | bl br bl br
Cla.—1 -AR e NA a i f i 2
Clo. 1 ae al e a ae i br br
Cor. 4402 2 pr fe 4 E g i í f
Coz. Ail br | bl i br br br
Cro. 3 WEDI i i bl
Cur. br | bl | bl br bl i 4
w. tii 2) i AD o ER ESS 3 bl br br
Dig.—A 242 1 br | bl | — — wo —
Doo. MiWi br br bl 1 4
Dra. o br | bl | br i i i
Dye. a. 2 1 bl | br | bl i br br
Edw. 3 2 bref i f f f
Edw. 4.2 2 Lh he Pst i y br
Eld. 3 1 Foe here f br br
Eve. 4 1 Eroa y f i
Fal. 5| 1 Lcd) be tb bl bl bl
Gla. 1 e e br f f
Gla.—B 3i 1 83-| br |} bl | bl br bl i
Goe. 1i i) be be br br br
Gre.—E 1 2. bE 4 bW br br br
Gri. oe eae | Ti br bE bE i bl br
Hag. br} f f br — — 4
Hal.—E br | bl | br bl bl 5
Han.—1 be tt bes be f f 2
Har.—D } bl | br | bl br br br
Hof. aif bl | br} bl br br br
Hom.—B 4 2 1 bi be |: bi bl a ae
Hur. 2 2c bef yb f f f
Hyd.—1 GHE] Tier f br £ br
Jal. - 4 be tg f br f f
Jem. br | bl | bl br br bl 2 1
Jen. ti 2 sihrit i br f -=
Jon.—B 3 3 | bl | br | bl bl br bl
Jon.—1 24% d.br| f i i f
Jon.- f id.br} f f br br 3 1
Koc.—1 1:3 S | tel ft be i f f
Koc.—2 bl | br | bl i i br Aí
Lot.—A 8 2 | br! bl | br br br br
Lym.—1 br | bl | br] br | br 3
Lym.—2 3 ft ibe is f i i
Mai 4|3 1 fiche tot f br f
No. 527] SKIN PIGMENTATION IN MAN 649
: 5 = =] | | © i |
Family Name. g 3 = |M F. |MM.| MF. | FM.| FF = s =
a |a| A | a | «4 |
Mat. 2 | bl | br | br br bl br |
McC. 5 | br f | br f | br
Mil. 3 | 2 br | bl | bl bl i
Mil.—B 2 4 | bl | br} bl bl br br
Moo. | | br} bioi br i i 2
Owe.—1 | | HEr F f b — | — 2
Par. 2 | Beh Erber i f f br
Pat. 5 | | | br | bl | br i br br 1 3
Pre. g2 i Be bes ob Bh be
Red. 2 | | br | bl | br i bl bl
Rei.—1 wae Ett gape Oe a eo f dbr] f
Rel. 1| | 21) br] bb} — —| —
Ril. $4 2 A EE S A ee 4 i i
Sca. 3 mon oe E e bl bl br
Smi.—E br | bl | bl —| — | 4
Spr. 2 2 bl | br | — dark |
Ste.—C 2 3 bl | br i bl br i |
Ste.—2 2 be bed tT
Str.—D 2 bl | br| i br br bl
Syk. a ones | 1 | bl | br | — — br | br
Tat. 5 | br | bibr br | bl} bl
Van.—1 Lipes E f w pre r Aea eie i
Ven.—1 4| 1 E a eae i | br| br
Vos. ite | bl | br} i i bri br |
War.—A 1 1 | br} bl | br i i i
Wen. 4 | 2 2a beet ii f — i f
Whi. t vbe v.br to Vibe | Qf
Whi. 2 4 4 f br f f br f
Whi.—3 S422 2 fbr of i f br
Wil. 2 3i bii bej i bl br | br |
Wol. P TA D i 1 fi Bet of d.br | i f |
Wor + ee Oi | bl | br | bl b |=| = |
Wyb 4 wti i dar pe |
Total (342) |193| 58 | 91 | (60) | 0 | 30| 31
Total: 88 families. 70 families. v.br, very brown. 18 families.
given in Table II, and are divided into two classes, viz.,
those containing blond offspring, on the left side of the
table, and those containing none, on the right side. The
division is made in accordance with the hypothesis that
‘‘brunet’’ is dominant to ‘‘blond’’ and that the brunets
may be of two sorts, either duplex or simplex, in respect
to the pigmentation character. If the pigmentation fac-
tor of the dark parent is duplex no blonds are to be ex-
pected, but if the dark parent is simplex in pigmentation
half of the children will have little or no black skin-pig-
ment. By hypothesis the simplex parents should be
about twice as numerous as the duplex. In Table II
there are 70 families with blond children to 18 without
650 THE AMERICAN NATURALIST [Vou. XLIV
blonds. Some of the latter are doubtless without blonds
by chance, owing to the small number in the family, just
as there are 30 families in the entire 88 without brunet
offspring or 39 without intermediates. That all of the
families without blonds are not so by chance is probable
from the following considerations: (a) blonds are al-
most (11:12.8) as numerous as the other two classes
together yet the latter are both absent in the offspring
of only eleven families; (b) there are more large fam-
- ilies that are blondless than that are without brunets
and intermediates, and when a large family is without
offspring of a particular class the result is less probably
due to chance. Finally, owing to the fact that the de-
velopment of potential pigment is frequently retarded,
some of the families with ‘‘blond’’ offspring would later
be without blonds. We may conclude, then, that some
of the blondless fraternities are so because all of their
members have the determiner for skin pigmentation and,
consequently, in the brunet X blond matings some of the
brunet parents are duplex in skin pigment. But the off-
spring of these duplex parents are not all alike; half of
them are ‘‘intermediate’’ and the remainder ‘‘brunet.”’
This result suggests that brunets may carry the ‘‘inter-
mediate’’ grade of skin pigmentation as a hidden—
hypostatic—factor.
In the families containing blond offspring, expectation,
on the hypothesis of segregation, is that half of the off-
spring shall be blond and half pigmented in full or
intermediate grade. Actually blonds are to non-blonds
as 193:149 or as 1.3:1. The excess of blonds suggests
that some of them are immature and potentially pig-
mented, the families really belonging to the right hand
side of the table.
(c) Brunet X Brunet (Table IIIT)—When both pa-
rents are brunets there may, on the segregation theory,
be two classes of families, namely, a class in which both
parents produce germ-cells without the pigment deter-
miner and a class in which at least one parent produces
no such germ-cells. In the former case only are blond
No. 527] SKIN PIGMENTATION IN MAN ` 651
TABLE III
COMPLEXION: BRUNET X BRUNET
: E ] 3 j
SS Sh Peas oy a ya eee
Family Name. $ È | E = | Bis = a E S $ | Š
Ait.—1 3 Bee br | bry f br f f |
Alt. 1 | 4 |br | br | bl] bl | br | — |
Arn.—2 | br | br | br i br i ae
Bal.—3 1 Tea fee Rs a i i br i br
Ban. 1 1 br | br | i br br br
Bay. br | br | br i br r 1 4
Blo.—1 br | b — br br 3 2
Bro.—B 2 tiwi bra ae Be Be i
Bu. 1 br | br ibr t bl — br
Can. br | br | br br br bl 2
Cla.—D 2 1 4 bë f br | br br lt lt
Col.—D 2 2 br | br i br i r
Eni. br | br | i br br br 3
Fie. 3 1 1 br | br | i br br i
Fis. br | br | br br i ooo 3
Gim. 1 D iak ake f dk | dk: dk
Gre.—C 1 4 br | br | br — i ——
Hen. br | br | br br br br 3
Hen br | br | br i br — Lovie S
Jac.—1 2 1 br | br | br f i f
Jor.—2 1 1 1 br | b — | — br br
Kay br t br Dr br i br Zoi g
Kel. 4 8 dicbro be -pr f br f |
Kil. 2 1 prt bry i — |—| — |
Kub. r| br br bl br 1 2
Lan. 1 3 br? | br? | bl bl bl bl
Lan. 2 T Ebr br br br br
McB. br | br | br br br 5
McC. 2 1 Br be ae br — —
Mel. 2 8 ibri ii f br
Mor.—A br | i i br br 2
dk | dk} i br br br 1 2
Pib.—1 br | br | br br br br 7
—2 br | br | br br i br 5
Pon 2 1 br | br | br bl br —
Ram br | br | br br br br 3
Rob.—B br | bri i i br 1 3
Sin.—D br | br | br br br br 3 1
as br | br | i br i br 2 3
3 2 2 | br | br | br bl i
Wro.—B br | br | br bl br bl 2
You. 2 1 Iili be be ol i bl br
Zin. 1 4 | br r Lo bl —
Total (96) 42 t 111 438 | | (77) O | 19 | 58
Total: 43 families. 23 families. 20 families.
offspring to be expected. Among the 43 families of
Table III, 20 produced no blonds, although some of them
comprise four to seven children. Consequently it is
highly probable that some brunets are duplex in skin pig-
mentation. In the families that produce blonds there are
652 THE AMERICAN NATURALIST [ Vou. XLIV
only 54 children out of a total of 96 that are either
brunet or intermediate, or about 56 per cent. of all. With
simple segregation and dominance 75 per cent. of dark
offspring are to be expected; the deficiency is, I suspect,
partly due to the exclusion from the left side of the
table of some families with both parents simplex merely
because they failed (in their small families) to produce
blonds, although they were potential blond producers.
(d) Intermediate X Intermediate (Table IV).—The
intermediate class serves to include those whose skin
has not the clear, transparent, pink quality of the typical
blond, on the one hand, nor the rich dark shade of the
brunet. It was intended to include a considerable range
of color from 10 per cent. to 18 per cent. of black in the
color wheel. As already stated, however, collaborators
assigned less than a third of the offspring to this class.
The distribution of skin color in the offspring of two
intermediates offers, it must be freely admitted, great
difficulties. There are several possibilities. It might
be that the ‘‘brunet’’ type of skin color is typical for
skin pigment. Accordingly, the intermediate condition
may be conceived as having been stopped part way in
- color development. This stoppage may be due to the
fact that the units essential to the later phases of color
development are lacking, or to the fact that the stimu-
lus to full pigmentation is weak. The first alternative
assumes many units for pigmentation; the second, one
unit that fluctuates widely. Again the intermediate con-
dition might be the consequence merely of its simplex or
heterozygous nature. If the latter were the case two
intermediates should produce light and dark offspring |
again in nearly equal proportions as well as intermedi-
ates. But if either of the two first-named hypotheses
is correct, in accordance with results found by us in
hair color, the offspring should not exceed in pigmenta-
tion the more pigmented parent; in the same way that in
the offspring of two blond parents the parental color is
not exceeded.
Table IV gives the data precisely as reported. As in
653
So Te ee | eo | me ee eT | gege | me me me Tee | e E Ete ee Ear
me ne mie ee Toe | g | m | me ee te e me e | Teen | -g | =m | = | dee E be soe | me Fen ee | ae ete
No. 527] SKIN PIGMENTATION IN MAN
TABLE IV
INTERMEDIATE X INTERMEDIATE
Children. |
Family Name. M F MM. MF
Fair. | Inter. | Brun. |
ase PI Rg E E
Ave.—1 5 a | br i
Bal.—A 6 i kota i
Bal.—B 1 1 i i
Bar.—2 3 4 2 by f
Bar.—A 2 4 | f i
Bar.—3 2 2 | f
Bat.—B 1 2 | br
ec. 5 i
Bec.—B 2 i
Bed. 2 i
Bre.—1 2 i
Bel.—1 1 1 2 br f
Ber. 2 3 i
Bis. 3 3 1 br
Bla. 3 2 1 bl
Bra.—4 3 j br
Bra.—D 1 4 1 bl i
Bro.—9 3 f i
Bur. 2 2 br i
Bur.—3 3 i
Cad.—2 5 d f
Cal.—1 3 br
Cap. 2 2 i
Cas. 1 9 br
Cha. 2 1
Cla.—2 1 3
Col. 4
Con. 5
Con. 1 1 1 br bl
Con.—D 3
Con.—E 2 2
Cox. t 4
Dar.—B 2
Dar.—D 4
Dav.— 2
Dav.—E 1 6
Dol.—1 13
Don.—1 8 |
Ear. 1 bl
Eck.—1 3 1 2 f
Fer. 2 p ai
Gan 2 i bl
Gar. 1 4 9 i i
Gen. 2 2 EE Soi
Goo.—2 2 1 br f
Gra.—A 2 2 br i
Gro.—A 3 i =
ue, 6 2 2 1 1
Had.—B 3 dk bl
Hal. 1 L i bl
Har.—A 4 3 3 bl bl
Har.—1 3 i i
Har.—2 1 7 il i
Haw. 3 =. | DoE
Hay. 1 2 1 y : br i
654
THE AMERICAN NATURALIST
Family Name.
[ Vou. XLIV
Children.
M. MM. MF. FM. FF,
air. | Inter. | Brun.
1 1 i i i i
f 1 1 bl br —- -—
6 i i i
2 3 f —— f
4 i i i
4 i i i
1 2 i i i
2 i ie i
1 1 1 br i f
2 3 br br
3 f f
1 1 i br
5 i i
3 i i
4 2 bl i
2 2 1 i i
1 1 bl i i
4 bl br bl bl
3 9 — — — =
4 br i
1 5 i
2 1 bl br
5
3 j
2
2 br
1 3 bl
3 3
2 2 br l
1 5 br -br
4 i
3 1 i
2 br br
1 5 1 i i
1 8 pi br i i
3 f br i
4 1 i bl
4 i i
x I br bl br
2 8 i
2 1 i ->
9 i i
1 1 bl i bl
9 i olive
1 1 i i i
2 1 2 br i br br
2 1 1 f f br
1 3 i i i
1 1 3 i br br
4 i i br
5 i i i
3 i i i i
2 4 i ca ig le see
2 2 4 i i i i i
Bo dete i i i i i
No. 527] SKIN PIGMENTATION IN MAN 655
Children. |
Family Name LYM F MM MF FM FF
Fair. | Inter. | Brun,
Sam.—A 1 Bea: i br bl br
Say. 2 i i br
Sea. 1 1 f i i
Sil.—B 3 br i br
Sil.—C 2 1 i bl i
Sin. 2 i i i
Smi.—3 4 i i i
Sml. 3 i i i
Sne. 2 i i br
Sob. 1 2 br bl bl i
Squ. 5 i br i
Ste.—1 2 2 i br br
Sti.—1 2 i i i
Sto.—C 1 1 i i i
Str.—C. 2 br bl i
Str. 3 i bl i bl.
Str. 2 — — — —
Sny. 4 i i i i
Tay.—D 3 i i i i
Tho. 2 2 bl br br i
Tre. 4 i i i
Tru. 3 2 i bl à
Wal. 4 1 i i
Wal.—2 T i i
Wan. 3 i i
Wan.—B 1 1 — i
War. 2 f f dk dk
Wes. 1 br bl bl
Whe.—D 1 1 bl i i
Wil. 2 i bl br
Wil. 1 3 1 — — br
Wil.—B 1 2 i dk br
Win. 1 2 i i i
Wol. 1 1 2 br br bl
Totals (591) |128 403 60
the case of the other tables, a certain allowance has to be
made for errors in reporting due to vague and incorrect
recollection and to other mental lapses. In such fam-
ilies as Keh., McC.—2 and Rob. the color of one of the
parents is probably incorrectly reported. Sometimes the
probability of the record can be tested by considering
the associated hair color, since there is a fairly high ċor-
relation between the two. Thus in the case of the Keh.
family both ‘‘intermediate’’ parents have ‘‘black’’ hair,
while all but one of the ‘‘brunet’’ children have hair
that is recorded as of some shade lighter than black. In
the McQ.—2 and Rob. families both parents and children
have ‘‘dark brown’’ hair, but, in both families, the skin
656 THE AMERICAN NATURALIST [ Von. XLIV
TABLE V
INTERMEDIATE X BLOND
Children.
Family Name. x M. F. MM. MF FM. FF
Blond. | Inter. | Brun. | |
Ave 4 i i bl i i i bl
Bal. 3 1 1 bl i bl br —— —
Bar 2 i bl i br bl i
Bon. 4 i bl i i bl bl
Bow. IEE i bl i i — i
Col.—C 7 kog bl i bl br i bl
Dav.—C 2 -2 bl i = -= br i
Dru. ae i bl i br br e
Ege. 2 bl i bl -— bl —
Ewa. eed bl i i i i i
Fin. 1 1 i bl i br i i
Fra. 3 1 2 i bl oa — — be
Fra.—D 2 i bl — — — ==
Fri.—B 1 2 i bl i i i bl
Gen. 3 bl i i i i i
Gil.—B 3 i i bl i br bl i
Gor.—A 2 7 2 bl j bl i i i
Gsc. 2 | i bl br bl bl bl
Hal. 4 b br bl br
Hal.—D 1 1 b i bl i
How.—D 3 p i bl i
Hur. 1 3 b i i i
Kel. 1 1 b bl i bl
Kir. 1 1 b i i i
Lat.—B 3 bl i i
a. 1 1 1 b bl bl bl i
Mil.—D 2 br i br bl
Mos. 2 3 H i i i bl
Pie. 2 bl i i br i
Pla.—C 1 bl br bl i bl
Pra. 4 4 bl bl i dk dk
Ras,—B 1 4 bl bl br — a
Rob. 3 4 bl i i bl 1
Seo. 3 2 1 bl bl br bl br
Sco.—B 2 bl bl bl i i
Sha. 5 bl i i bl i
Str. 4 2 bl bl bl bl —
Suo. F i bl br bl -— bl
Tw. 3 1 bl bl bl -— ——
Vos. 2 1 bl j br bl i 1
Wal. 4 bl i bl bl bl
Web. 6 1 bl bl br br br
Wri. 3 i bl fair i bl i
Wro.—C 1 1 i bl i br bl bl
Totals: (179)| 96 75 8
44 families.
color of the parents is given as ‘‘intermediate,’’ while
that of all or most of the children is given as ‘‘brunet.”’
It seems probable that in applying the terms that were
available the difference in skin color between parents
and children has been unconsciously exaggerated.
657
SKIN PIGMENTATION IN MAN
No. 527]
INTERMEDIATE X FAIR
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46 families.
1Medium brown to dark brown hair.
2(í Black’? hair, hazel eyes.
658 THE AMERICAN NATURALIST [ Vou. XLIV
Applying no correction at all, however, practically 90
per cent. of the offspring agree with the rule that they
are not darker than their darker parents. Nevertheless,
the hypothesis that intermediate skin color is sometimes
due to the imperfect dominance of the simplex deter-
miner must be admitted as plausible.
(e) Intermediate X Blond—The results of this mat-
ing are given in Table V, showing the distribution of
skin color in the offspring. If all intermediates were
simplex in skin pigmentation we should expect blonds
and intermediates in equal numbers. Also on the hy-
pothesis that the higher grade of pigmentation is epi-
static we should expect blonds and intermediates, but no
brunets. The actual distribution agrees nearly with ex-
pectation on either hypothesis: where the term ‘‘blond”’
is used 54 per cent. of the offspring are blonds; and
among the ‘‘fairs’’ 56 per cent. are fair. Most of the
remainder are ‘‘intermediate,’’ the exceptions consti-
tuting only about 6 per cent. of all offspring. In some
of the most aberrant families, like Dar.—1, one finds in
the hair color reason for doubting if classification was
always made with judgment. It seems probable that
when the parentage really falls into this class brunet
offspring rarely, if ever, occur.
(f) Intermediate Brunet (Table VI) —If cntewmadi:
ate skin color is simplex then brunet is duplex and ex-
pectation is that half of the offspring shall be brunet,
half intermediate and there shall be no blonds. But if
intermediate and brunet represent two different stages
of pigmentation either of which may be epistatic to
blond, then a certain proportion (sometimes less than 25
per cent.) of the offspring should be blonds. Actually
there are many blonds (about 24 per cent. of all off-
spring) and consequently the second hypothesis is fa-
vored again.
Of the 80 families 39 have no blond offspring; we may
inquire if the ancestry of such families differs in the
proportions of the blonds from those that produce blond
offspring. We find that in the families with blond off-
No. 527]
SKIN PIGMENTATION IN MAN
TABLE VI
BRUNET X INTERMEDIATE
659
Family Name. a | Inter. | Brun. | M. F. | MM. | MF. | FM. | FF.
ea. $ 2 5 br i i bl bl i
Bis.—2 2 1 i br i br i br
Boh.—3 5 1 3 br i — — — —
Boy.—2 1 4 i br — — bl =
Bro.—7 2 1 i br f i br br
But. 1 2 i br br br br br
Clu.—A 3 i br me -— --— —-
Clu.—B 1 1 1 i br i -— — ~| —
on. 3 2 2 br i bl i bl bl
ur.—A 1 1 br i bl bl bl i
Cur.—1 4 2 i br f i i br
Dav.—A E 4 2 i br -— = as —
Dep. 2 i br i — i br
Dev. 2 i br bl br -— bl
Dey.—A 2 4 br i br br i br
on. 1 1 5 br i bl bl bl i
Don.—B 1 3 i br i bl bl br
Dow.—1 5 br i f br f f
Dru. 2 1 br i — -= -— aH
Eas. 2 i br br i f br
Fyt. 2 3 i br — — i br
Gar.—A 2 3 i br br i br i
Gar.—1 2 3 sf br i i br i f
Gan, 3 3 br i i i i I
Get. 3 2 i br i i i i
Gil. 2 2 br i br f i f
Gla.—A 6 2 i br i bl br br
Gra.— 3 2 br i i br i i
Gre. 2 i br br br i i
Had. 2 br i i br br i
Han. 2 br i bl br bl i
Har. 2 br i br i i i
Hay. 1 2 br i -— br br f
Hen.—A 2 1 i br br i br bl
Hew. 3 2 3 br i i — bl br
Hir. 1 1 br i br br i i
Hit. 2 i br i i i br
Hop. 1 1 br i i i br
Jor.—1 2 1 br i br i i
Ker. 1 1 br i i i i
Kro.—1 1 2 1 br br f br i
Leo. 2 1 br bl br br i
Lon.—C 1 r- br br i i i
Lue 1 2 1 br br br i br
McG 2 1 br j j br i
McK 2 br f i br i
McL. 2 ng i br br br —
M 2 2 br i i i i
Mar. 1 2 br i f i i
Mil.—A. 1 $ 1 br i i br br i
Mit.—C. 3 i br br bl br
*Nic.—A Í 1 3 i br br br bl
Nic.—1 2 3 i br br br i
Oe. 5 i br i br br
Pal 1 1 br i f br f br
Poe. 2 1 br i br br i i
660 THE AMERICAN NATURALIST [ Vou. XLIV
smn a z sap Dead j RS CO ss iad ~
Family Name. | Blond | Inter. | Brun
jor F air.|
Met F | MM. | ME. | FM. | FF
Pyn. Cy yea aes cl ere ae ee ey tr be
Rie—3 | 2 | Be n f br olobe oi
Roc. | 3 2 : Eole beo toi i br | br
Rol. 5 1 be | br br i i
Say. ft Lok be a e e | le
Sch. oe | 4 | br | i br f | f f
SSG SN oe ee ee CoP er gee shu seer
Sel. | LIS i br te. eee br
Ser. | E T ae | i br | bl br br
Sho. | i 2 pt a oh br i
Ski. arai 1 | 2 i | wo i ea ae
Smi. a ee br | i Bae to oe es ee wee
Spi. bo 8 | br Te ES a ie te Be eh a
Ste—D | $4 wo ek i | —
Sto.—B | 1 | i boa Cra | br br
Tho. | 3 | i br | i l br ioa
Tre. Dorot br i br br ED, esc
Tue. aS | wos | io oe bl | br
Tyd.—1 ee Gace Pe] ore i i hoe
Ver. kod ae br i i bl i | br
Way. 2 | 1 1 i br | — os iod
Web. 1 ra leta i | i
Wei. 1 1 1 res See” eee bl br
Woo. 6 1 i brs i br | i | br
| / |
Totals (307) 73 | 129 | 105 | | | | |
80 families. Certain grandparental terms are printed in italies to indi-
cate our doubt as to their correctness.
spring 24 per cent. of the known grandparents are re-
corded as blond or fair, whereas in families without .
blond offspring only 13 per cent. of the known grand-
parents are blond or fair. In families with blond off-
spring 9 of the 34 complete sets of grandparents (or
26.5 per cent.) show blondness on both the paternal and
maternal side, whereas in families without blond off-
spring, of the 36 complete sets of grandparents only 4,
or 11 per cent., show blondness on both sides, and the size
of the families in these four cases is small, viz., 2, 2, 2,
4, so that there is a large chance that the families are
potentially blond producing and really belong in with
the blond producing families. It appears, then, that
both the intermediate and brunet parents may contain
hypostatic blondness, and where they do they will have
blond offspring, but not otherwise.
If the brunet parent is, in any case, duplex-brunet and
contains no hypostatic intermediate or blond then ex-
No. 527] SKIN PIGMENTATION IN MAN 661
pectation is that all of its offspring shall be brunet.
This condition is apparently not realized even in the 29
families that yield no blonds. Only in seven cases are
both [grand] parents of the brown parent ‘‘brunet,’’
but there is no evidence that they were not simplex. At
any rate, in all these seven cases some ‘‘intermediate’’
offspring were produced.
(g) Comparisons.—The relations of the foregoing
facts are better brought out by the compact table where
the results of the various matings can be compared.
TABLE VII
THE NUMBER AND DISTRIBUTION OF THE OFFSPRING OF VARIOUS MATINGS
| RG Popor
Nature of Mating.
| Total. | Blond. | Inter. | Brun. | Blond. | Inter. | Brun.
ees | SERES | aS) Eii
Bignd X< blond e. ees f= 513 469 35-4 9 91.4 6.8 1.8
haar EN abe tt Eee a | 408| 224] 158 26 54.9 | 38.7 6.4
Biond X braneeton a] 403 193 88 122 47.9 | 21.8 | 30.3
flake, 591 128 | 403 60 | 21.8 | 68.5 | 9.7
] iret ea eee 307 73 | 129 105 8 | 42.0 | 34.2
Brunet Xbrunet............ | 173 42| 30 | 101 | 24.3 | 17.3 | 584
Totali oer et ee | 2,394 | 1,129 | 843 | 423 |
Considering alone the proportions of blonds in the
families of the various matings, some striking figures are
obtained. Three classes appear:
I. Class comprising about 90 per cent. blonds ap-
proaching 100 per cent.—blond blond (91.4 per cent.).
II. Classes in which the blonds constitute approxi-
mately 50 per cent.—blond X intermediate (54.9 per
cent.), blond X brunet (48 per cent.).
III. Classes in which the blonds constitute approxi-
mately 25 per cent.—brunet X brunet (24.3 per cent.), ©
brunet X intermediate (23.8 per cent.), intermediate X
intermediate (21.8 per cent.).
In the first class neither parent shows skin pigment;
in the second class one parent only shows such pigment;
in the third class both parents show skin pigment. The
proportions of blonds in the first class are those ex-
pected from Mendelian crosses of R X R; of the second
class those expected from R X DR crosses, and of the
662 THE AMERICAN NATURALIST [ Vou. XLIV
third class those expected from DR xX DR matings.
Shall it therefore be concluded that all brunets as well
as intermediates are simplex in skin pigment? This
does not follow; but it does seem to be a fact that duplex
‘*brunet’’ and ‘‘intermediate’’ are not common ;! indeed
so uncommon as not to alter materially the proportions
that would be given on the hypothesis that they are al-
ways simplex.
The principle of the nope whens of the upper
limit to which we have called attention elsewhere? seems
to hold for skin pigment also although the result is less
clear-cut, probably because the terms were less accu-
rately assigned. To see how closely the law holds Table
I has been constructed. The three cases: (a) darker
parent blond; (b) darker parent intermediate; (c)
darker parent brunet—are chosen and the distribution of
offspring in each case indicated at the right.
TABLE VIII
SHOWING THE DISTRIBUTION OF THE DIFFERENT CLASSES OF SKIN COLOR IN
HREE CASES WHEN THE DARKER PARENT IS BLOND,
INTERMEDIATE AND BRUNET
ohia. |
} Proportions.
Frequency. |
Totals. | Blond.
Inter, | Brun. Blond. | Inter. | Brun.
A ANAE EA S E wip Uren ET | 513 469 35 9 91.4 6.8 1.8
e ak pur ees: | 996 352 561 83 35.3 | 56.3 8.3
Wi eee eet eo 30 247 328 34.9 280 LITI
Table VIII shows that exceptions to the rule of de-
limitation are, considering the vagueness of terms,’ rela-
tively rare, only about 8 per cent., and, consequently, the
rule seems verified.
The significance of the intermediate grades of skin
color is a question of prime importance. There is some
evidence, for example in Table IV, families Har. A, Keh.
*For examples of probably duplex ‘‘ brunet ’’ see Table III, Eni, Hen,
McB, Ram. Of duplex intermediates there seem to be examples in Table IV,
, Dol.—1, Don.—1, Ran.—B, and Ree; and in Table V, Suo
"O 0, and C. B. Davenport, 1909,
p. 208.
*The proportion would be substantially reduced were returns that show
intrinsic evidence of error eliminated.
No. 527] SKIN PIGMENTATION IN MAN 663
and Rob., that the intermediate condition is sometimes a
simplex or heterozygous condition. But, in most cases
the evidence is clear that the ‘‘intermediate’”’ grade (or
grades) is simply epistatic to blond and hypostatic to
brunet and that intermediate may carry, and usually
does carry, hypostatie ‘‘blond,’’ while brunet may carry,
and usually does carry, either or both hypostatie blond
or hypostatic intermediate. There is nothing unpre-
cedented in the conception that a given condition may be
in some cases simplex and in others act as a unit. Some
cases of barring in the plumage color of poultry belong
to the one category and others to the other.
The meaning of the case of skin pigmentation, like that
of hair pigmentation, is not perfectly clear. There is a
possibility that pigmentation stops at certain well-de-
fined points, each of which is determined by an hered-
itary unit; on the other hand, it seems even more prob-
able that there is a continuous gradation in depth of
pigmentation and that the strong internal conditions
that lead to deeper pigmentation dominate over the
weaker conditions. In the one case the varying char-
acteristic is composed of a series of steps; in the other
of an inclined plane. But a series of steps can not be
distinguished from an inclined plane if the steps be taken
small enough.
D. HEREDITY OF SKIN PIGMENTATION IN
CROSSES BETWEEN WHITES AND
NEGROES
The behavior in inheritance of the very dark skin pig-
mentation characteristic of negro races now deserves
consideration. It is remarkable that despite the abun-
dance of material available the facts of the inheritance
of pigmentation in such crosses should have remained
so long in dispute. To settle the question whether segre-
gation occurs, two essential conditions must be met.
First, the parentage of the children must be unques-
tioned and, second, the degree of pigmentation must be
quantitatively expressed. Through the kind coopera-
664 THE AMERICAN NATURALIST [Von. XLIV
tion of correspondents in the south and above all of Pro-
fessor H. E. Jordan, of the University of Virginia, who
furnished all of the quantitative data, I am able to meet
these conditions.
The quantitative data were obtained by means of the
Bradley color top, using the standard colors of the Mil-
ton Bradley Company, of Springfield, Mass. The num-
bers given are percentages of the entire area of the disc
occupied by the corresponding colors on the revolving
disc. All color determinations were made of the dorsal
aspect of the forearm slightly above the wrist. The de-
terminations by the color top indicate that human skin
color is obtained by mixing black (N), yellow (Y), red
(R) and white (W). The first constituent is the melanic
pigment, the second probably is due to a lipochrome pig-
ment so wide-spread in animals and found in the human
hair and iris, the red is chiefly that of hemoglobin; and
the white is reflected from the opaque skin. The color
formula of the skin of the wrist of a slightly tanned
‘‘white’’ skin—the writer’s—is as follows:
N y R Ww
8 9 50 33
The determinations by the color top are fairly deli-
cate. The formula 10-12-41-37 gives a decidedly dif-
ferent color from the foregoing and not red enough for
any wrist-skin. The skin color of a very dark negro,
about 18 years old, measured by Dr. Jordan gave: N 75,
Y 3, R 20, W 2. Dr. Jordan thinks the skin color of this
boy’s face would be given by N 90, R 10. Another black
negro is given by N 68, Y 2, R 26, W 4.
We may now consider the pedigrees of skin color col-
lected by Dr. Jordan.
As to the question of legitimacy, Dr. Jordan writes:
‘‘There isn’t the least doubt, I think, about the legitimacy
of the children in the families of ‘H.,’ ‘W.,’ ‘J.’ and ‘F.’5
* The quantitative data on this family were not obtained, as the members
were too inaccessible. The ‘‘C.’’ family was obtained after Dr. Jordan’s
letter was written, and his remarks are doubtless applicable to that family
also.
No. 527] SKIN PIGMENTATION IN MAN 665
W. FAMILY
3 (white) = ¢ (negro) 3 (mulatto) r (mulatto)
—
$ (mulatto; = Ọ (mulatto; color ¢ (mulatto) = Ọ (mulatto)
ae a or of of 12-year old grand-
ga] daughter)
[i I
g (mulatto ; = Ọ (mulatto, ‘‘ very dark ”’;
13-17- -35-38) | 45-12-33-10)
|] I |] l |] l l |] l
3 Q 2
19 15 yrs. 13 yrs. 12yrs. 10 yrs. S8yrs. Tym. 5 yrs.
sent; ‘‘color of N 25 32 46 23 33
color of father?” Y 20 14 7 15 4 17 16
12-year absent 30 37 40 30 30 35 28
old 17 24 60 25 33
ter
H. FAMILY
3 (mu-=9 ier 3 (white)=9 (negro) & (negro)= 9 (white) $(?)=9(?)
latto) latto
d oiai color = 2 (mulatto) 8 (mulatto) = ? (mulatto)
of “ Har rry YO
H MN: p? Piia i an b Light mulatto
brown mu -0-32-18
36-14-32-18
l I | |] ]
$ 2 2 8 2
ohm J Mas yrs ) (18 yrs.) (16 gn (12 yrs.) (8 yrs.) (6 yrs.)
SA absent, 2 27 39 28
20 liite lighter skin color 13 18 13 18
32 than father; like 20- 36 33 38 32
18 slightly year-old 19 22 10 22
han brother
oldest sister
C. FAMILY
8 2 8 X 3 5 6 ?
(mulatto) = (mulatto) (white)—negro (white) =(mulatto) ( teire =— (negro)
an
Indian )
& (mulatto; scons S imane lighter ¢ (mulatto = PAE tage waa
of Charles) an Charles) light ter than | color of
Chas wife) Charles’ wife)
g “Charles ” ; dark yellow = 4 EER slightly ruddier
mulatto arles)
43-13-22-22 4 7 s- 13
|] |] | | e
(16 yrs.) (15 yrs.) a$ ) (5 yrs.) (3 a )
yrs yrs yrs yrs yrs
35 32 1
17 15 17 2i
32 35 81 31 33
15 20 18 16
666 THE AMERICAN NATURALIST [Vor. XLIV
J. FAMILY
8 x 3. ¥ 8 2 8 2
(white) (mulatto) (white) = (negro) (white) — (white) (negro) = (negro)
| | | |
3 (mu = 9 (mulatto lighter 8 (white) = Q (negro)
Aar John) than John)
“ce >?
8 “John (mulatto) = = 9 (almost white)
29-20-33-18 | 13-15-36-36
l l ihe: l } I
2 3 3 2 8
(31 yrs.) (27 yrs.) (23 yrs. ) (21 yrs.) (18 yrs. ) (11 yrs.)
absent ; 10: 10* 8.5 absent ; 28
like 5 5 16.5 “darker 17
eldest 37 36 32 than John’’ 33
brother 48 49 43 22
Dr. F for years a resident of this section, and health
officer of C——, supports me in this belief. Moreover, I
have explained to each family the necessity for my study
of absolute certainty on this point, have asked them the
direct question, and each about the other, and can get
only the assurance that the family life in each case is
entirely chaste. One man is a minister, one principal of
the colored school, one a thriving merchant and one a
barber, and all seem considerably above the grade of
morality and intelligence of the ordinary stupid and ir-
responsible negro. I think you may be absolutely cer-
tain regarding the chastity of the several mothers con-
cerned.” Those who know Dr. Jordan will appreciate
the better the great weight to be given his conclusion.
It seems to us we may proceed to discuss these cases as
experimental data.
Of the four families the W. family is, perhaps, the
most striking. The father, the grandson of a white man,
has himself a grade of pigmentation (black, 13 per cent.)
no darker than that of a brunet. His wife is very dark
(black, 45 per cent.). The children range from white
(black, 6 per cent.) to as dark as the mother (46 per
cent.). The entire series of percentages of black runs:
6, 23, 25, 31, 32, 33, 46. We have here 1 light inter-
mediate; 5 of mulatto tint and 1 ‘‘very dark.” None of
* These measurements were made an hour apart, after shifting of the color
dises and the later without recalling the earlier measurement.
No. 527] SKIN PIGMENTATION IN MAN 667
the children show a significantly greater pigmentation
than the darker parent, and one is lighter than the
lighter parent. There is clear evidence of segregation
of the skin pigmentation.
The J. family is important because of the mating of
an ‘‘almost white’’ first generation mulatto with a male
mulatto who is more than twice as dark. Of the four |
children measured three are nearly white, whiter than
the mother, and one is as dark as the father. The series
runs: 8.5, 10, 10, 28. A segregation of practically white
and half dark (grandparental colors) takes place here
also.
The H. family has also several points of interest. A
lighter and darker mulatto parent (black, 30 per cent.
and 36 per cent., respectively) from four mulatto grand-
parents have children ranging in amount of black pig-
ment from 27 to 39; these extremes being somewhat
lighter and somewhat darker, respectively, than the pa-
rents. No white appears. This result is like that ob-
tained in many Caucasian families with ‘‘intermediate’’
skin color; where two ‘‘intermediate’’ parents (that
apparently do not have hypostatic oe breed true.
They behave like “pure dominants.’
The C. family gives much the same result. Two second
generation mulattoes of rather dark type have children
of this dark type only. None of them exceed the darker
parent; some of them run lighter than the less pigmented
parent. These parents also seem ‘‘pure dominants,’’
or, better, contain no hypostatie white.
The significance of the data of these four families is
perfectly clear in view of the studies that we have made
on the inheritance of hair and skin color in ‘‘Caucas-
ians.’’ There are many grades of pigmentation—more
or less definite stopping points, perhaps, in a continuous
pigmentation process. A tendency to proceed far in the
pigmentation process is dominant over the less progres-
sive condition, but imperfectly so. Consequently, first-
generation mulattoes are not as dark as the negro pa-
rent. Whether in the offspring of two such mulattoes
668 THE AMERICAN NATURALIST [ Vou. XLIV
the ‘‘extracted dominants’? would ever return to the
original pigmentation of the dark negro parent is doubt-
ful; first, because neither ‘‘white’’ nor black is a single
unit. Only in rare instances will the ‘‘extracted’’ blacks
be free of some white unit. We are dealing in this case
not with two unit characters only but perhaps with a
myriad of them. A chance combination of a lot of lower
grades will give ‘‘white’’ skin; a combination of ‘‘dark
units” free of any ‘‘white units’’ would give a dark
skin, but most of the offspring will show the various
intermediate grades due to diverse combinations of the
black and white units. As a rule, even in the first hybrid
generation, the darkest grade that is potential in the
protoplasm tends to show in the offspring; and so, as a
general rule, offspring are rarely darker than the darker
parent.
To the foregoing quantitative data may be added
some qualitative evidence concerning inheritance of
skin color in black X white crosses. This testimony is
all that I have been able to collect of a definite nature
and it has all come from persons possessed of negro
blood.
Professor W. E. DuBois, of Atlanta University,
Georgia, writes:
Strictly speaking a mulatto is a child of a white person and a full-
blooded negro. . . . [Their] children are liable to vary greatly... .
They might be light in color or dark in color . . . or freckled, with
red curly hair.
Maj. R. R. Moton, of the Hampton (Va.) Normal and
Agricultural Institute, writes:
Mulatto parents very often have children that are practically white
so far as external appearances are concerned, and the same parents
may have children that are black or very dark brown. This is very
common. Indeed, I think it is more often that the children vary
than not. ;
He cites three examples, all of families whose fathers
hold positions of trust in Hampton; two in the institute.
A. ‘‘is a mulatto and so is his wife. Their first child was
a pir. A distinct blond in hair and complexion.
No. 527] SKIN PIGMENTATION IN MAN 669
The second child was very dark, darker than either
father or mother.’’ B. ‘‘is a mulatto and his first wife
was a mulatto. Their first child, a girl, was... just the
complexion of the father and mother. The second child,
a boy, was very dark.” C. ‘‘is a mulatto, and his wife is
also a mulatto. Their first child, a girl, is darker than
either mother or father; not black, however. The sec-
ond, a boy, is much lighter than either mother or father;
almost white. The third, a girl, is a‘distinct blond with
Saxon eyes and complexion. fe
Professor T. B. Williams, of Hampton Institute,
writes:
I know two large families in which both parents in each family are
practically white. All of the children are like the parents, practically
white. In fact some of them have left home and are “ passing for
white ” in other sections.
These cases are important as indicating that the lower
grades of pigmentation do not produce the higher grades
(except that some mulatto tints produce darker children
by extraction of the white). Professor Williams con-
tinues:
In another family the mother is practically white, the father, a
mulatto, is darker. They have six girls. Five of them are practicall
white; one is a very light yellow. In another family the father and
mother are as nearly pure mulattoes as are commonly found. One
parent is in each case, I am pretty sure, white, and the other in each
ease is a pure or nearly pure negro. The children of this couple vary
from the parents both ways. The older child is fairer than the parents
and even has blue eyes, while theirs are dark. The younger child is
darker than the parents, though not “black, or nearly so.” I could
multiply these illustrations may times. There are, too, settlements of
mulatto people who for some generations have taken pains not to
m: among darker colored people but have gone on intermarrying
yet I have never seen a black person as a result of these unions.
In addition to these data from colored people we have
the following from Professor H. V. Wilson, of the Uni-
versity of North Carolina. The family was reported to
him by a physician.
Parents, fairly light mulattoes. Woman virtuous. - Several children.
All children but one, the ordinary type of mulatto; characteristies inter-
670 THE AMERICAN NATURALIST [Von XLIV
mediate between negro and white. One child shows segregated char-
acters, has blue eyes and other characters close to those of white race.
Finally we give sundry fragments of pedigrees fur-
nished by two reliable and highly intelligent colored per-
sons. Owing to the slight social sentiment among most
colored persons against unchastity, they have little mo-
tive to hide from one another the facts of parentage of
children. Consequently the facts as given below are
probably correct. “
B. FAMILY
8 (white brunet; = Ọ colored; dark ĝ white; Caucasian = Ta colore
Jewish) | brown right brown
rc
8 e] Ọ brunet $ yellow
| l
? 3
brunet blond
E. FAMILY
& ‘‘colored’’ = 9 ‘‘colored’’ g Caucasian = 9 Meo eg ;
mul igh white
atto light | mulat
|
& very light = 9? white
almost
white
white ;
blond hair
G. FAMILY
£P. G0 BO, SHR ee 9 16, 4G,
colored colored Caucasian mulatto
brown very light white brown
& J.G: = a G
very light | mulatto brown
i i T Í
3 g 9 E;
mulatto light mulatto light
rown brown
P. FAMILY
8 ‘‘colored’’ = 9 M. H. ‘colored’? 8 Caucasian = Ọ Caucasian
white brown white whi
32G P. z= 2
mulatto | white
ODP
No. 527] . SKIN PIGMENTATION IN MAN 671
S. FAMILY
= 9 ‘‘colored’’
omer eee Aw W. Bes Oe ei vy - 7 oJ. W.
Caucasian ‘* colored” mulatto | mulatto “colored”?
brunet dark brown white | lightyellow yellow
OG. 8, se f S AM e oe $ beg Were
light brown yellow ‘‘colored’’ “ colored ’’
white yellow
| | | I
g GNS. SES 9 MS. EN: N:
white brown white light brown
W. FAMILY
* Gaacasan J * Caucasian “Cavcasian | dice: Pe Seat kii and
dark brown brown Indian onea
eaueasian sala light Sas | Jik brown
=a l
whit dark brown
The following families are the product of North Amer-
ican Indian and white crosses.
Bes. FAMILY
FABE
4 Indian | white
blond
l l l l
a i E Oo L: B: 2 M. B. AEB. oB:
blond blond brunet brunet brunet
Coo. FAMILY
A ES ae A. E-
very light Indian
brown
é D. C.. = ọ . M.
very light | brown
ES l I Eol
ODE 3 F.C. Q E.C. LCG Se 3
interm. dark light interm. ayer
twins
blond, blond
In some of these families segregation is apparent,
notably, in B., G. and S., and Bes and Coo.
inally, we may refer to an observation made by
Louis Agassiz (1891, p. 532) in Brazil which bears upon
the matter of segregation, both of skin color and other
672 THE AMERICAN NATURALIST [ Vou. XLIV
characteristics. After referring to the striking differ-
ences between the white X negro, the Indian X negro
and the Indian X white hybrids, and stating that the
Indian characters are the more deeply impressed on the
offspring, he says:
I have known the offspring of an hybrid between Indian and negro
with an hybrid between Indian and white restme almost completely
the characteristics of the pure Indian.
The conclusion from these various data, qualitative as
well as quantitative, is that skin color in negro X white
crosses is not a typical ‘‘blend’’ as conceived by those
who oppose the modern direction of research in heredity,
but that, on the contrary, the original grades of heavy
and slight melanogenesis segregate in the germ cells—
often imperfectly because of the multiplicity of units (or
grades) for skin pigmentation—and thus the original
color characters are more or less perfectly restored.
All studies indicate that blonds lack one or more units
that brunets possess; that the negro skin possesses
still additional units; that individuals with the heavier
skin pigmentation may have slight pigmentation covered
over—hypostatic, evidence of this condition appearing
in the light offspring of such hybrids in the second or
third generation; and that first-generation hybrids fre-
quently show, somatically, a color grade less than that
which they carry potentially and may segregate in their
germ cells.
( To be concluded )
THE COLOR SENSE OF THE HONEY-BEE: CAN
BEES DISTINGUISH COLORS?
JOHN H. LOVELL
Can bees distinguish between differently colored floral
leaves? If they can not, then, a polychromatic flora
possesses no advantage over one in which the flowers
are all of the same hue. In the Alpine flora, says Ker-
ner, on the heights above the tree-line, there is actually
no spring and no autumn, only a short summer following
a long winter. All the flowers have, therefore, to blos-
som in a short time. ‘‘ White and red, yellow and blue,
brown and green, stand in varied combination on a
hand’s-breadth of space.’’! These color contrasts, it is
believed, enable bees easily to remain constant to a single
plant species so that pollination is effected to the mutual
advantage of both insects and flowers. If the flowers were
visited indiscriminately, regardless of their form, much
pollen would be wasted and not a little time and effort
would be lost. Genera adapted to bees, according to
Miiller, display a variety of colors, especially when they
bloom simultaneously in the same locality, as Aconitum
lycoctonum yellow, A. napellus blue; Lamium album
white, L. maculatum red, Galeobdolon luteum yellow;
Salvia glutinosa yellow, S. pratensis blue; Pedicularis
tuberosa whitish yellow, P. verticillata purple.
If the different colors were evolved, as I believe, because of the power
and necessity in bees of discriminating between them then it is not
wonderful to find represented among bee flowers not only white, yellow,
red, violet, blue, brown and even blackish (Bartsia) in the most varied
degrees, but also to see several colors in the same flower combined in
manifold ways. I mention only Polygala Chamebuxus, Viola tricolor,
*Kerner, Anton, ‘‘ Natural History of Plants,’’ translated by F. W.
Oliver, 2, pt. 1, 198. Also see Plate XII., ‘‘ Alpine Flowers in the Tyrol,’’
drawn from nature by E. Heyn.
673
674 THE AMERICAN NATURALIST [Vou. XLIV
Cerinthe major, Galeopsis versicolor, Astragalus depressus, alpinus and
many other Papilionacee. ;
On the other hand, it is asserted by Plateau that all
natural flowers might be as green as their leaves without
their pollination by insects being compromised ;? while
in the opinion of Bethe bees are mere reflex machines and
have no senses, or ability to make experiences and modify
by them their actions.* If either of these extreme claims
is admitted, it is evident that a variety of colors can be
of no benefit to flowers. It seems desirable, therefore, to
consider what experimental evidence is available to prove
that bees can distinguish differences in color.
It was first shown by Lubbock (Lord Avebury) that
honey-bees can distinguish between ‘‘ artificial ’’ colors,
or slips of paper of different hues. An account of his
experiments is given at considerable length in his well-
known book on ‘‘ Ants, Bees and Wasps ’’; but, as they
were performed more than thirty years ago, I shall de-
scribe a number of experiments made myself, in some of
which the conditions have been varied. I shall endeavor
to show not only that bees can distinguish between the
colors of papers, of flowers and of painted hives, but that
they can learn not to discriminate between them, when this
is for their advantage. Their behavior in detail will like-
wise be carefully recorded.
On a pleasant September morning I accustomed a yel-
low (Italian) bee to visit a strip of blue paper® three
inches long by one inch wide. To prevent the paper from
blowing away or becoming aor k was covered with a
* Müller, Hermann, ‘‘ Alpenblumen,’’ p nuth, Paul, ‘‘ Handbuch
m o a ell 1, 141, or ‘‘ Handbook one Tian Pollination,’’ trans-
by J. R: Kiieworth R L i7.
ai FO Félix, ‘‘ Les eia et la couleur des fleurs,’’ L’Année Psy-
Ee 13, 79.
el-Reepen, H. v., ‘‘Are Bees Reflex Machines?’ PPR by
ih a Geisler, p. 3. Bethe, Albrecht, ‘‘ Dürfen wir den Ameisen und
Bienen psychische Qualitäten zuschreiben?’’ p. 86. Emil Strauss, Dona.
1898.
*The colored papers used were obtained from the Milton Bradley Co.,
SA Mass., and were produced in pure spectrum colors by having
e surface conted. Stained papers have the colors somewhat broken.
No. 527] COLOR SENSE OF THE HONEY-BEE 675
transparent glass slide of the same dimensions, upon the
center of which a small quantity of honey was placed.
These slides are used for mounting microscopic objects,
and may be obtained of any dealer in opon! instruments
for a trifling sum.
After the bee had made a number of visits to the blue
paper, a red slide of the same dimensions, and prepared
as described above, was placed six inches to the right of
it. An equal quantity of honey was also placed upon the
center of this slide. When the bee returned from- the
hive it alighted on the blue slide, which still remained in
its original position.
On the departure of the bee for the hive the slides were
transposed, i. e., the red put in the place of the blue and
the blue where the red had been. When the bee returned,
and no longer found the blue paper in its usual position,
it flew back and forth, examining both slides, paused for
a second or two on the red, then resumed its flight, but
finally settled on the blue. A little later it flew up into
the air, but soon returned to the blue; then it flew across
to the red, where it remained for the rest of its visit. The
change in the position of the blue, and the discovery of a
differently colored slide also bearing honey, evidently
disturbed the bee; and its frequent flights showed that
it was endeavoring to orient itself to these new condi-
tions. As will now appear it did not find it necessary to
repeat this course of reconnoitering.
While the bee was away I transposed the slides for a
second time, the distance apart being as before—six
inches.. The bee returned directly to the blue. Twice it
left the blue for a few moments, but each time returned
to it.
When the bee left for the hive, I again transposed the
slides; the bee returned to the blue. The bee left for the
hive, and I transposed the slides. It returned to the blue.
While the bee was away I transposed the slides for the
fifth time. The bee returned to the blue. Then it left the
676 THE AMERICAN NATURALIST [ Vou. XLIV
blue slide, flew across to the red, but at once returned to
the blue.
The bee left for the hive and I transposed: the slides.
On its return it circled about as though in doubt and
presently disappeared from view; but a little later it re-
turned and settled on the blue. While taking up its load
of honey it left the blue three times, but in each instance
returned.
_ The bee left for the hive and I transposed the slides.
It returned to the blue.
The bee left for the hive and I transposed the slides
for the eighth time. On returning the bee hovered close
to the red, and then went to the blue.
As soon as the bee returned to the hive, I transposed
the slides for the ninth and last time. When the bee
came back, it alighted after a little hesitation on the blue.
It left once and flew across to the red, but soon returned
to the blue. Left a second time but soon returned. Then
it flew into the room, and on being released went back to
the hive. |
There can be no question that in this experiment the
honey-bee was able to distinguish the blue color from the
red. I repeated the experiment many times and varied
it in many different ways, but the bee always showed its
ability to distinguish between differently colored slips of
paper. Only one bee should be employed, for if there are
two or three they will conflict and to some extent produce
confusion. :
For the purpose of comparison the following experi-
ment, in which a larger number of colored slides was
employed, was performed on the morning of September
20, six days after the experiment just related. A black
or German bee, instead of an Italian bee as before, was
accustomed to visit a blue slide prepared as described
above. After a number of visits had been made, the blue
slide was moved to the right about seven inches, and a
red slide put in its place. The bee returned to the blue.
As soon as the bee left for the hive, the slides were
No. 527] COLOR SENSE OF THE HONEY-BEE 677
transposed. The bee returned to the blue. The bee again
left for the hive and I transposed the slides. It returned
to the blue.
When the bee left for the hive, I transposed the slides
for the fourth time. The bee returned to the red, which
was now in the place occupied by the blue at the time of
its previous visit.
The bee left for the hive, but no change was made in
the position of the slides. On its return it again sought
the blue, showing that the influence of this color was still
dominant, though it now knew from memory as well as
from its visual and olfactory senses that honey was to be
found on the red.
A yellow slide was now placed upon the board about
seven inches to the left of the blue. The order of the
colors was yellow, blue, red, and their distance apart
seven inches. The bee returned to the blue. When the
bee left, I transposed the yellow and blue so that the order
was blue, yellow, red. The bee returned to the blue. On
the departure of the bee I again transposed blue and yel-
low. The bee returned to the blue.
When the bee left for the hive, a white slide was intro-
duced and the distances between the slides reduced to four
and one-half inches. The order of colors was yellow,
white, blue, red. The bee on its return flew back and forth
several times over the slides, and after hovering in the
air for a few moments in hesitation alighted on the white.
The bee left for the hive, but no change was made in
the order of the slides; it returned to the blue.
When the bee left, a black slide was substituted for the
white one. The order of the slides was yellow, black,
blue, red and the distances apart remained as before
four and one-half inches. The bee returned to the yellow,
but soon left it (perhaps disturbed by a fly) and returned
to the blue. No change was made in the order of the
slides, and the bee returned to the black. But on its next
visit it again sought the blue.
I now transposed the red and blue, bringing blue to the
678 THE AMERICAN NATURALIST [ Vou. XLIV
extreme right so that the order was yellow, black, red,
blue. The bee returned to the blue. The red and blue
were again transposed, the bee returned to the black, but
soon left it for the blue. Black and blue were then trans-
posed, the bee returned to the blue. I next transposed
yellow and blue, bringing blue to the extreme left, the
bee returned to the red. No change was made in the
order of the slides, the bee returned to the yellow. The
slides were again left unchanged, the bee touched on
black, then on red, but finally alighted on blue. Red and
blue were transposed so that the order of colors was red,
yellow, black, blue. The bee returned to the black. No
change was made in the slides, the bee returned to the
blue.
During the first five visits, when there were only blue
and red slides, the bee returned four time to the blue and
but once to the red. This single exception is not without
value, since it shows that the bee had the power of choice,
and that its behavior was not mechanical, or that of a re-
flex machine. During the next three visits blue, red and
yellow slides were employed and the bee returned every
time to the blue. During the following thirteen visits
four slides were used (blue, red, yellow, white in two
visits; blue, red, yellow, black in eleven visits), and the
bee naturally showed greater hesitation and an increas-
ing tendency to visit other colors than blue. Still it took
up its load eight times on blue to once on white, once on
red, once on yellow, and twice on black. In every in-
stance where the bee selected another color than blue, it
will be observed that it was after the slides had been
transposed, or a color had been changed; and that with
one exception it again returned to blue on the next visit.
Of the total twenty-one visits fifteen were made to the
blue, but not more than two to any other color. The bee
steadily endeavored to remain constant to the blue,
though this involved both loss of time and effort; and the
number of exceptions is surprisingly few when we re-
member that before the close of the experiment the bee
No.527] COLOR SENSE OF THE HONEY-BEE 679
had learned from experience that there was an ample sup-
ply of amber-colored honey on each of the four slides.
The purpose of my next experiment was to determine
whether bees could readily determine a colored slide from
a plain glass one. On September 10, 1908, I accustomed
a line of Italian bees to visit a yellow slide. I then moved
it six inches to one side, and exactly in its place I put a
glass slide, under which there was no colored paper. A
small quantity of honey was placed on the center of each
slide. During twenty minutes the bees were carefully
watched, and twelve visits to the yellow slide were
recorded. A species of Vespa had built a nest not far
away, and some of the workers also came to the yellow
slide, and although they were an extraneous or foreign
factor not directly connected with the experiment, their
behavior was not without interest. Near the end of the
time mentioned one of the wasps discovered the honey on
the colorless slide and subsequently visited it. A bee
attracted apparently by the presence of the wasp on this
slide alighted beside it, but after a few moments flew
across to the yellow.
I now transposed the slides, the distance apart remain-
‘ing six inches as before. During ten minutes the Italian
bees made eight and the wasps nine visits to the yellow
‘slide. Only one visit was made to the colorless slide and
that was by a wasp. Another wasp alighted on the color-
less slide for a few moments before going to the yellow.
There were a number of visits made by flies, all of which
were to the yellow. In this experiment not only was the
colored slide easily distinguished from the one without
color, but it was apparently more attractive not alone to
the bees, which had been trained to visit it, but to inci-
dental visitors such as the wasps and flies. There were,
moreover, no exceptions to the fidelity of the bees to the
yellow color, as there were in the earlier experiments,
when they were given the choice between two colors.
The preference of the bees for the yellow slide was,
indeed, so marked that possibly it might be objected that
680 _ THE AMERICAN NATURALIST [Vou. XLIV
the plain glass slide was invisible, or at least very incon-
spicuous. Such a supposition would be a mistake, for
while it was certainly less conspicuous than the yellow
slip, it could yet be seen clearly by the aid of reflected
light and the amber-colored honey at a distance of more
than ten feet. A year later on October 11, 1909, this was
established by experiment. Two black bees were trained
to visit a plain glass slide. While they were absent, the
slide was moved six inches to the right, and a blue slide,
which owed its color to the floral leaves of the bee-lark-
spur (Delphinium elatum) was put in its place. One of
the bees returned to the colorless slide. When it left I
moved the colorless slide twelve inches to the right of the
blue slide. In this position the bees visited it twice. I
transposed the slides. Both bees returned to the colorless
slide, and a little later one of them came again. As no
visits had been made to the blue slide, there could be no
question but that the bees saw the plain glass slide.
As the result of his experiments with artificial flowers
Plateau assumes that the artificial colors of paper or of
cloth appear to bees of a different tint or tone than do the
colors of natural flowers, which to human eyes are ap-
parently of the same hue My own investigations lead
me to believe that this assumption is not well founded,
and is not required to explain the behavior of bees under
the conditions described by Plateau. The discussion of
this question, however, would lead to too long a digres-
sion from the subject under consideration, and must be
deferred to some other opportunity. But in passing it
may be remarked that the readiness with which Bethe
and his followers assume new forces and powers to sus-
tain theoretical positions is not a little amazing to the
prosaic naturalist content to work with known factors.”
* Plateau, F., ‘‘Les insectes et la couleur des fleurs,’’ L’ Année Psychol-
ogique, 13, 77. ‘Comment les fleurs attirent les insectes,’’ 5th part, Bull.
Acad. roy. Bel., 3° série, 34, 847-881, 1897. ‘Les fleurs artificielles et les
insectes,’? Mem. Acad. roy. Bel., 2™° série, 1, 3-103.
* Bethe holds that the bees are led back to the hive by a wholly unknown
force. ‘‘Diirfen wir Ameisen und Bienen psychische Qualitäten zuschreib-
en?’’ p. 77, Bonn, 1898.
No. 527] COLOR SENSE OF THE HONEY-BEE 681
There is the less need of delay for inquiring into this
imaginary power of vision, since bees as easily distin-
guish between the colors of flowers as between those of
colored papers.
As the result of more than twenty-six hundred experi-
ments on the color sense of the honey-bee Hermann Mil-
ler was convinced not alone that they could distinguish
colors, but that they exhibited color preference.’ Instead
of colored paper he made use of floral leaves, which he
placed between two object slides, the edges of which were
afterwards sealed with a soluble gum. The slides em-
ployed by myself were made as follows: A grayish-white
slip of cardboard three inches long by one wide was cov-
ered with the yellow rays of a garden sunflower, over
which a glass slide of the same dimensions was placed
and tied firmly with black silk thread. In like manner a
blue slide was prepared from the blue perianth of the
bee-larkspur (Delphinium elatum), and a red slide from
three bright red flowers of the Zanzibar balsam (Impa-
tiens sultant).
On September 29 I accustomed several yellow or Italian
bees to visit the yellow or sunflower slide. The slide was
then moved eight inches to the right, and in its place was
put the blue slide made from the floral leaves of the bee-
larkspur. There was a small quantity of honey as usual
on the center of each slide. At the same time I removed
three of the bees, leaving only one. The time was 3
o’clock p.m., and the slides were in the shade. The bee
returned to the yellow.
The bee left for the hive, and I transposed the slides.
It returned to the yellow.
The bee left for the hive, and I transposed the slides.
It returned to the blue.
When the bee left for the hive, no change was made.
It returned to the yellow.
As soon as the bee left for the hive I transposed the
$ Müller, H., ‘‘Versuche über die Farbenliebhaberei der Honigbiene,’’
Kosmos, 11, 273-99. Reprinted as a separate by R. Friedländer & Sohn,
Berlin, 1883.
682 THE AMERICAN NATURALIST ` [Vou. XLIV
slides for the fifth time. Two bees returned, one of which
alighted on the yellow, the other on the blue. There could
be little doubt that the bee which alighted on the yellow
was the one which was under observation. This decision
was based partly on its appearance (young bees can easily
be distinguished from old ones), and partly because it
was probable that it would return to the yellow. Its sub-
sequent behavior satisfied me that this conclusion was
correct. The bee on the blue was removed.
The bee on the yellow left for the hive and I transposed
the slides. It returned to the yellow.
The bee left for the hive and I transposed the slides.
The bee returned to the yellow, but presently left it, de-
scribed a few circles in the air, and then again settled on
the yellow.
The bee left for the hive, and I transposed the slides
for the eighth time. The bee returned to the blue, but
soon left it, and after circling around in the air alighted
on the yellow, where it remained.
The bee left for the hive and I transposed the slides.
It returned to the yellow. |
During ten visits in only one instance did it take up its
load on the blue. The dominant power of the yellow
color is well shown in the case where the bee alighted on
the blue, on which there was an abundance of honey, but
soon left it for the yellow. In many other experiments,
in which the red slide was used as well as the yellow and
blue, the bees as easily discriminated between natural
colors as between those which were artificial.
On October 6 I performed the following experiment for
the purpose of determining whether bees were more
strongly influenced by a colored slide than by one without
color. A red slide, prepared from the bright red flowers
of Impatiens sultani, an exotic from Zanzibar, was placed
on a white box in the sun and about a dozen bees were
permitted to visit it for some time. Each of the blossoms
was an inch in diameter. At 10 o’clock in the morning a
plain glass slide was substituted for the red one, which
No. 527] COLOR SENSE OF THE HONEY-BEE 6383
was moved six inches to the right. There was a liberal
supply of honey on the center of both slides.
In a few minutes there were seven bees on the red slide
and two on' the colorless. The bees were now driven
away, the slides transposed, and the distance apart in-
creased to sixteen inches. Six bees and a fly (Eristalis
tenax) soon came to the red slide, but only one bee came
to the colorless. The number of bees on the red slide con-
tinued to increase until there were about eight,® and it
was difficult for some of them to reach the honey. In the
meantime there were only two bees on the colorless slide.
The bees were again driven away and the slides trans-
posed, the distance apart remaining sixteen inches. At
the end of a few moments there were eight bees on the
red glass, and one bee on the colorless. The slides were
transposed, and once more eight bees and the syrphid fly
came to the red, and only one bee to the colorless.
The bees were driven away, and the slides transposed.
Very quickly five bees selected the red, and two bees and
the syrphid fly the colorless. Later there were eleven
bees on the red, and only two onthe colorless. The bees on
the red slide were so crowded that this may have had some
influence in sending two of them to the colorless. The
honey on the latter slide was amber-colored and could be
seen at a distance of twelve feet, while at times its odor
must have been stronger than that upon the red slide,
since it was removed much more slowly.
It may be objected that the very marked preference
shown by the bees for the red slide was the result of their
having been accustomed to visit it first. If one bee had
been employed, this might be admitted, but in the case of
so many bees, it is improbable, since they would naturally
avoid continually crowding and interfering with each
other. If, however, the objection is well founded, then
they should continue to give the preference to the red
° As the bees were closely bunched together, and were frequently coming
and going, it was impossible at this moment to count the exact number
within one,
684 THE AMERICAN NATURALIST [Vou. XLIV
slide, when a bright-colored slide is substituted for the
colorless one.
Accordingly a blue slide was substituted for the one
without color, and at the same time the slides were trans-
posed, the distance apart still remaining sixteen inches.
The honey was disposed as a narrow band along the
center of each slide in order that it might be more easily
accessible to the bees. In ten minutes there were eight
bees on the red and two on the blue. A little later there
were ten bees on the red, and four bees and a wasp on the
blue.
The bees were driven away and the slides transposed.
Ina few minutes there were three bees and a wasp on the
red, and nine bees on the blue. Ten minutes later there
were six bees and an Eristalis tenax on the red, and four
bees on the blue. Two minutes later there were three
bees and the syrphid fly on the red, and seven bees on the
blue. Very quickly then after the blue slide was substi-
tuted for the colorless one, the bees ceased to exhibit a
preference for the red slide, and sometimes visited the
red and sometimes the blue in larger numbers. This
experiment thus affords evidence not only that bees can
distinguish colors, but that they are also influenced by
conspicuousness.?”
The experience of apiarists furnishes very conclusive
evidence of the power of bees to distinguish colors. The
hives are sometimes painted different colors in order that
the bees may mark their location with greater certainty
and avoid entering the wrong hive. A bee-keeper de-
scribes in Gleanings in Bee Culture how he painted his
hives red; white and blue, in order that the bees might
mark their location largely by color. I have, he states,
adopted the red, white and blue plan, since 1880, and am
so well pleased with the result that I am painting all my
new hives this spring in the same colors. It enables the
bees to avoid making mistakes and going into the wrong
* Lovell, John H., ‘‘The Color Sense of the Honey-bee: Is Conspicuous-
ness an Advantage to Flowers?’’ Am. NAT., 43, 338-349, June, 1909.
_No.527] COLOR SENSE OF THE HONEY-BEE 685
hives. If you remove a white hive, many of the bees will
pass the blue one on the one side and the red one on the
other side, and go into the white hives further on. This
shows conclusively that bees mark the position of the
hive by color as well as by its environment.
I admit that where a few colonies are kept in one place there is very
little danger of the bees mixing; but where you have long rows of hives
in sheds, as we have in Salt River Valley, the three colors will avoid a
great deal of confusion and save the lives of many bees and some young
queens.”
While this plan works admirably so long as the hives
are not moved, it of course, gives very unsatisfactory
results, if for any reason a hive is removed and one of
another color is substituted for it. When a colony swarms
naturally, says another apiarist, or is swarmed arti-
ficially, or for any reason the old hive body is removed,
unless the new hive is of the same color as the old hive
many of the bees will not return to it, but will scatter
among the hives nearest to the old location, which are of
the same color as the hive which has been removed. For
example if the dwelling of the parent colony was white
and if at the time of swarming an attempt was made to
put the swarm in a blue hive a large part of the bees
would refuse to enter it and would fly away to the
nearest white hive, with the result that the new colony
was materially weakened. He, therefore, found it more
convenient to paint all his hives one color.’
Another bee-keeper placed his hives in two house-
apiaries, each containing 150 colonies. The three end
hives at each end of the shed or house were painted green.
If now all the green hives at one end were removed, the
bees instead of entering the hives nearest to the old loca-
tion, which were painted a different color, flew to the
4 Lessing, Wm., ‘‘ Painting Hives,’’ Gleanings in Bee Culture, 34, 1428,
November 15, 1906. For this article I am indebted to Mr. H. H. Root,
editor of Gleanings in Bee Culture.
, Irving, ‘‘Color of Hives; A Variety of Colors Undesirable,’’
* Kinyon
Pi in Bee Culture, 35, 262, February 15, 1907. Mr. Kinyon writes
t about one third to one half of a swarm would thus be lost.
686 THE AMERICAN NATURALIST [ Von. XLIV
green hives at the other end of the house apiary, and tried
to enter them, even though they were closed.'®
These statements are confirmed by the experience of
W. Z. Hutchinson, an authoritative writer on American
apiculture.
One spring I bought and brought home about forty colonies or hives
painted a very dark gray, or almost lead color. They were set down in
the apiary by themselves in four different rows. In the course of a
few days I began transferring the bees from these hives into white
hives, like the rest of the hives in my apiary. I took an end hive first.
When the brood combs were set over into a white hive, and this hive
set down where the old gray hive had been, the bees refused to enter it,
but piled into the next hive in the row, which, of course, was gray like
their old home. This hive was soon filled to overflowing, some of the
bees hanging on the outside. I then transferred the combs from this
hive to a white one, but the bees refused to enter it and piled into the
next gray hive in the row. The hives were about three feet apart in
the row. A bee is guided to its home by location as well as color, and
after about four hives, or colonies, had been transferred, then some of
the bees began to enter the new, white hives, as the gray hives were
now so far from their old location that they perceived that they could
not be their home. The same trouble was had in each row that was
transferred.“
An excellent illustration of the effect of differently
colored hives is given by Buttel-Reepen:
A weak afterswarm, mostly of young bees from a hive painted blue,
dispersed among the masses of humming bees which were just taking
their flight of orientation out of the other hives (which, as is usually
the case in Germany, Switzerland and Austria, were standing close
together), and settled here and there in little clumps. After a short
time they flew back to the bee-house; but only a ae found the right
hive; the rest flew to other colonies, and to which? Only where a blue
door invited them did they attempt an entrance but nowhere else.
Unfortunately they were so hostilely received that the evant in front
of all the hives marked blue was covered with dead bees
The experience of apiarists, therefore, botki in America
and Europe furnishes indubitable evidence that bees by
thousands readily distinguish colors.
1 The experience of a neighbor of Mr. Kinyon and described by him in
a ibe to the writer
y Tutehinson, editor of Bee Keeper’s Review and author of ‘‘ Ad-
vanced ie Culture’’ in a letter to the writer.
Bopa soge ‘“Are Bees Reflex Machines??? p. 38, translated by
ase H. Geis
No. 527] COLOR SENSE OF THE HONEY-BEE 687
Additional observations might easily be given, but those
presented appear sufficiently conclusive. It has been
shown that bees can distinguish between the colors of
papers, of flowers, and of painted hives, and that they are
more strongly influenced by a colored slide than by a
plain glass one. It may well be doubted whether they
would ever have been capable of making long journeys
afield for nectar and pollen, if this visual power had been
wanting. To those unfamiliar with the habits of bees,
it will occasion surprise that the bee after it had dis-
covered and began sucking honey on the red slide (to
take for illustration the ninth visit of the first experi-
ment) should have voluntarily left it and gone back to
the blue for the larger part of its load. But its behavior
in this instance is quite in accord with the principles of
bee psychology. Bees, as Forel states as the result of
his own and the experience of Huber, Buttel-Reepen and
Wasmann, very rapidly form habits, and their attention
becoming fixed by frequent repetitions is not easily di-
verted.1® When the bee, which had been trained to visit
the blue slide, alighted on the red, it was disturbed by the
difference of hue and suffered a certain degree of mental
disquietude, which was not allayed until it returned to the
blue.
All of the higher Hymenoptera probably possess the
power of distinguishing colors. This has been estab-
lished for the social wasps of the genus Vespa by the
interesting experiments of the Peckhams. One of their
experiments very strikingly shows the value of color con-
trasts, and effectively refutes Plateau’s assertion that all
flowers might be as green as their leaves without their
pollination being compromised.
We once placed some dark red nasturtiums on light yellow paper near
the nest, and found that more than one third of the homecoming wasps
flew to them and hovered over them before entering. When light yellow
hasturtiums, nearly matching the paper in color, were substituted only
one out of thirty-six noticed them; and as the odor was as strong in
1 Forel, August, ‘‘ Ants and Some Other Inseets,’’ translated by William
Morton Wheeler, p.
688 THE AMERICAN NATURALIST [ Vou. XLIV
one ease as the other, it would seem that the color was the attracting
force.”
It remains to consider the numerous instances where
bees visit indiscriminately the differently colored varie-
ties of the same species of flower. Zinnia elegans dis-
plays white, yellow, orange, red and purple varieties;
Dahlia variabilis white, yellow, orange, red and purple;
and Centaurea Cyanus red, white, blue and purple
flowers. When visiting any one of these species for nec-
tar bees pass freely from flowers of one color to those of
another. Plateau says:
If in the case of the same plant species the varieties of distinct color
are in equal quantities, the insects pass without order from one color
to another.”
One summer in my garden a single plant of the scarlet
runner (Phaseolus multiflorus) produced pure white
blossoms, which offered a striking contrast to the normal
bright scarlet racemes; but honey-bees and bumblebees
(Bombus terricola) visited both as though they had been
of the same hue. Bees likewise ignore the differences of
color in the white, rose-red, and purple flowers of Scabiosa
atropurpurea. But this behavior on the part of bees
furnishes no evidence whatever that they can not distin-
guish colors.
Honey-bees in collecting pollen and nectar are faithful
as a rule to a single species of flower—they exhibit
‘* flower fidelity.’’ This is evidently for their advantage,
since if they were to pass continually from flowers of one
form to those of another much time would be lost in locat-
ing the nectar. Even whole colonies may follow this
order. Mr. M. H. Mendleson, of Ventura, California, one
of the largest UER ater on the Pacific coast, re-
lates that
In 1884, one colony out of 200 gathered exclusively from an abun-
dance of mustard bloom; the 199 gathered from the sages.”
" Peckham, George W., and Elizabeth, ‘‘ Wasps Social and Solitary,’’
p- 6, 1905.
* Plateau, F., ‘‘Les Insectes et la couleur des fleurs,’’ L’Année psy-
chologique, 13, 78.
Mendleson, M. H., Gleanings in Bee Culture, October 1, 1908, 36, 1204.
No. 527] COLOR SENSE OF THE HONEY-BEE 689
But if the species are closely allied in form and color,
as among the buttercups, spireas and golden-rods, the
bees do not carefully discriminate between them. Yet
even in these genera the honey-bee often exhibits a re-
markable power of distinguishing between allied species,
even when they are of the same color. I have described
in the American Naturatist how in an upland pasture
honey-bees showed a*marked preference for the flat-
topped corymbs of Solidago lanceolata (Euthamia grami-
nifolia) to the panicled inflorescence of S. rugosa.
They were repeatedly seen to. leave S. lanceolata, and after flying
about but not resting on the flowers of S. rugosa return to the plants
they had left only a few moments before. In another instance a bee
was seen to wind its way among the plants of the latter species until it
found an isolated plant of S. lanceolata. A plant of each of the above
species was bent over so that the blossoms were intermingled, appearing
as a single cluster; a honey-bee rested on S. lanceolata and it seemed
very probable that it would pass over to the flowers of S. rugosa, but
such was not the case, for presently it flew away to another plant of
the former.”
The bees must, therefore, have perceived differences
between these two species of Solidago, though they occa-
sionally ignored them.
When a plant species displays variously colored
flowers, it is obvious that they are alike in shape, odor
and nectar, and differ in color alone. Under these cir-
cumstances it is for the advantage of bees to pass from
one color to another, and this they speedily learn to do.
In an earlier paper I have pointed out that form is a more
important factor than color in determining the visits of
the long-tongued bees and butterflies.*_ This conclusion
is confirmed by Dr. Graenicher in a very important con-
tribution on the pollination of the Composite. After a
careful comparison of the effect of tube length, color,
and odor on the limitation of visitors, he says:
It may be stated that according to the results obtained from a study
” Lovell, John H., hae Colors of Northern Gamopetalous Flowers,’’
Am. Nart., 37, 453, July, 190:
= Lovell, John H., ‘ peg ‘Colors of Northern Gamopetalous Flowers,’’
Am. Nart., 37, 452 and 477-8, July, 1903.
690 THE AMERICAN NATURALIST - [Vou. XLIV.
of our Composite the proportion of short-tongued to long-tongued
visitors in these flowers is determined by tube length more than by any
other character of the flower.” :
In the flowers under consideration the important bar-
rier of difference in form is absent.
In the following experiment it is shown how a bee soon
learns to visit colors indiscriminately. On September 22
after a black bee had been accustomed to visit a slip of
blue paper, a series of seven differently colored slides
were arranged in the following order: black, green, blue,
purple, red, white, yellow, orange. The slides were three
inches apart, or twenty-two inches from end to end; and
there was a small quantity of honey on the center of each.
The bee returned the first time to the blue, the second
time to the purple, the third time to the purple, the fourth
time to the blue, the fifth time to the purple. It will be
observed that the bee ceased at once to discriminate be-
tween the blue and the purple—the two slides being ad-
jacent and allied in color. On its fifth visit before alight-
ing the bee hovered over the different colors for many
seconds, and later left the purple for the red, whence
after a brief stop it flew away to the hive.
During the next three visits the bee devoted much time
to the examination of the slides, but subsequently it paid
little attention to the colors. When the bee returned
from the hive, it flew about for a long time, touched on the
orange, but immediately left it and went to the blue. On
its seventh visit the bee after describing a few circles in
the air, touched on the red, then on the blue, went back to
the red, and finally stopped on the blue. The colors were
arranged in the following order: black, red, blue, white,
green, orange, purple, yellow. On its eighth journey be-
fore alighting the bee flew from the vicinity of the blue
over to the yellow and back to the blue where it remained.
There could be no doubt that it was examining the slides,
as it flew close to them touching them at times.
I transposed the blue and green slides so that the order
= Graenicher, S., ‘‘ Wisconsin Flowers and their Pollination—Compos-
ite,’’ Bull. Wis. Nat. Hist. Soc., 7, 42, April, 1909.
No. 527] COLOR SENSE OF THE HONEY-BEE 691
was black, green, white, blue, orange, purple, yellow. On
its ninth visit the bee returned to the red; on the tenth to
the green, then going to red and white, but finally coming
back to the green. On its eleventh and twelfth visits the
bee returned to the blue. I transposed the blue with the
yellow and the red with the purple so that the order of
the colors was black, purple, green, white, yellow, orange,
red, blue. The thirteenth and fourteenth visits were
made to the yellow, the fifteenth to the white, the six-
teenth and seventeenth to the yellow, the eighteenth and
nineteenth to the blue—on the last visit it was disturbed
by a wasp and went to the orange. The twentieth visit
was to the yellow, the twenty-first to the green, and the
twenty-second to the yellow.
It is evident that at the beginning of this experiment
the behavior of the bee was widely different from what
it was at its close. Habituated to visit the blue slide, it
continued constant to this slide or the allied purple dur-
ing its earlier visits; though again and again by means of
its visual and olfactory senses it examined and compared
the other slides, as has been described. Repeated trans-
positions of the blue paper gradually weakened its fidelity
to this color, until at last similarity of form, honey and
odor prevailed over dissimilarity of color, and the bee
visited the slides indiscriminately. This result might
also have been brought about by permitting the bee to
remove all the honey from the blue slide, when it would
have turned from necessity to one of the other colors.
This is no doubt what happens in nature. A bee finds
usually in one flower only a portion of its load of nectar,
and so is compelled to examine other blossoms, which, if
they are alike in form, it will soon visit without order
even though they differ in color. If there are a number
of bees, their efforts to avoid visiting the same slide or
flower will greatly hasten the breaking down of the color
= barrier. In a location frequented by a few bees for honey
I put out the following series of colors: white, blue, green,
black, red orange, purple. In a few minutes there was a
692 THE AMERICAN NATURALIST [ Vou. XLIV
bee on every color save black and.orange, and a little
later there was a bee on each of these slides. The tota!
number of bees was twelve.
That bees can by the aid of their sense perceptions
draw ‘‘ simple instinctive inferences’’ has also been
shown experimentally by Forel. In a bed of dahlias
of various colors he mounted red, white and blue paper
flowers, in each of which was placed a drop of honey. A
red, a white flower and a rose-colored piece of paper with
a dry dahlia dise were each brought to the attention of a
bee. Thenceforth these three bees, which were marked
on the back with blue, yellow and white paints, returned
regularly to the artefacts and no longer visited the
dahlias.
The painted bees entirely of their own accord, undoubtedly through
an instinetive inference from analogy, discovered the other artefacts as
soon as their attention had been attracted by the honey on one of them,
notwithstanding the artefacts were some distance from one another and
of different colors. For were not the dahlias, too, which they had pre-
viously visited of different colors? . . . It would be a fallacy to con-
clude from this that they do not distinguish colors.”
CONCLUSIONS
Bees easily distinguish colors, whether they are arti-
ficial (paints, dyes, ete.) or natural (‘‘ chlorophyll ’’)
colors.
Bees are more strongly influenced by a colored slide
than by one without color.
Bees, which have been accustomed to visit a certain
color, tend to return to it habitually—they exhibit color
fidelity.
But this habit does not become obsessional, since they
quickly learn not to discriminate between colors when
this is for their advantage.
* Forel, August, ‘‘ Ants and Some Other Insects,’’ translated by William
Morton Wheeler, p. 27.
SHORTER ARTICLES AND DISCUSSION
THE ARITHMETIC OF THE PRODUCT MOMENT
METHOD OF CALCULATING THE COEFFI-
CIENT OF CORRELATION
In view of the increasing application of refined statistical
methods to scientifie problems of all kinds it seems highly de-
sirable to point out any simplification of arithmetical method
which may lighten the necessarily formidable labor of calcula-
tion.
The statistical constant which has proved a most powerful
tool in many fields of work is the coefficient of correlation. Be-
sides the contingency constant!, the correlation ratio? and the
well-known four-fold table and product moment methods, sev-
eral alternative processes of determining correlation in the case
of special data have been suggested.* In recent numbers of
Science Dr. Boast and Professor Pearson® have discussed the
formule to be used in the calculation of r, and in another place
I have suggested methods’ which in some cases materially
shorten the labor of calculation.
When the nature of the material permits, the best method of
calculating correlation is the product moment one.
As conventionally described in the books,’ this requires for the
* Pearson, K., ‘‘On Contingency and its Relation to eines se Nor-
mal Correlation,’’ Draper’s Co. Research Memoirs, Biometric S 1904,
? Pearson, K., ‘‘On the General Theory of Skew Redes. s Non-
linear Regression,” ibid., 2, 1
3 Fo e, K. Pearson, On Further Methods of Determining Corre
lation,’’ id. 4, 1907; K. Pearson, ‘‘On a New Method of Destia
Correlation,’’? Biometrika, Vol. VII, pp. 248-257, 1910; K. Pearson, ‘‘
a New Method of Doberialiings Correlation,’’ Biometrika, Vol. VII, pp.
96-105, 1909.
t Boas, F., ‘‘ Determination of the Coefficient of Correlation,’’ Science,
N. 8., Vol. X XIX, pp.
5 Pearson, K., ‘‘ ae ae of the Coefficient of Correlation,’’ Science,
N. S., Vol. XXX, pp. 23-25, 1909.
, J. Arthur, = short Method of Calculating the Coefficient of
en in the Case of Integral Variates,’’ Biometrika, Vol. VII, pp.
218, 1910.
potent G. U., ‘£On the Theory of Correlation,’’ Jour, Roy. Stat. Soc.,
Vol. LX, p. 812; Davenport, C. B., ‘ er Methods’’; Elderton, W. P.,
tt Frequency Curves and Gareintion.’
693
694 THE AMERICAN NATURALIST [ Vou. XLIV
calculation of S (sy): (a) the writing down on the margin of the
correlation table of an assumed mean, V,, of both the x and the
y characters, and the plus and minus deviations of the different
grades from these origins; (b) the entering in the body of the
table of the products of the deviations of the several classes of x
and y from their respective assumed means, care being taken to
regard sign, (c) the summation of the products of the class fre-
quencies of x and y by the first two powers of their deviations
from their assumed means; (d) the multiplication of the fre-
quencies in the table by the products of the deviation of z and y,
and the summation of their products, with regard to signs.
This gives
S(2’), SCP), Sy’), Sy’), S(2’) | N= de, S°) N=,
S(y’)|N= dy, Sly") = vf, and S(2’y’),
from which we may obtain the moments and the products mo-
ments about their true means by the use of the formule:
Clean V v,/ — d2,
oy = Vil = ae,
S(zy) = S(x’y’) — Ndzdy,
r= S( zry) | Nowy.
Frequently there are several possible ways of carrying out the
arithmetic for a given formula, and the one chosen is largely de-
pendent on the mental and mechanical traits of the computer.
Personally I have found the process described rather cumber-
some, and in using it—especially through the hands of assist-
ants—have found slips coming into the work with unfortunate
frequency.
The chief difficulty lies in the fact that the products of the
deviations of x and y from their assumed means must be written
own as indices to the frequencies in the body of the table itself.
This requires considerable time if the table be at all large, and
there is no way of checking the results for blunders except to
go over the entire process again. After this has been done, all
the multiplications of the frequencies into their indices must be
carried out ard the products summed. If the ranges of variation
be at all large, say even no higher than 20 classes each, one may
have to multiply some frequencies by such products as 63, 64,
72, 81, ete., and the labor becomes rather great.
Now since the formule given above enable us to refer the
moments or the product moments taken about any arbitrary
No.527] SHORTER ARTICLES AND DISCUSSION 695
point or origin to the true means, I have found the following
method to result in a material saving of time and energy.
If for y arrays of integral variates* we take 0 instead of the
grade thought to be nearest the mean as the origin, we at once
obtain the total for the array by summing the products of the
frequencies by their grades. By anal piy tng up by the grade of
x character we at once obtain S(2’y’).
I illustrate by a table re the relationship between the
number of ovules formed and the number of seeds developing
per locule for a series of pods of Hibiscus Syriacus taken in the
Missouri Botanical Garden in the autumn of 1907. Table I gives
the data.
TABLE I
“0 i Dn i -à z 3 4 5 | 6 | Ti 8 9 | Total.
3 Oe ee ea en mee a a ene ee 3
4 eer ieee eer ae e a po ee ae
5 osi mel 197): yap 1s | se a gee
6 | 732 | 1,148 | 1,415 | 1,598 | 1,865 | 1,829 | 1,212 | — | — |—| 9,799
7 | 208| 350| 450| '525| 635| 690| 714 |433| — |—| 4,005
8 | 112| 208| 300| 244| 326| 368| 395 | 255/151 |—| 2,359
9 AE eS E oe ES rey E r
Total | 1,129 | 1,839 | 2,319 | 2,535 | 2,986 | 2,975 | 2,324 | 697 | 156 | 5 | 16,965
Ovules per locule = æ, seeds per locule =y
The total number of seeds developing for each ovule-class is
found with great ease and rapidity by multiplying the frequen-
cies by the number of seeds per locule and summing at the same
time on the machine.® This gives Table II. By multiplying the
TABLE II
Ovule Class. eae aia. Total Seeds.
3 3 3
4 67 125
5 687 1,834
6 9,799 32,649
7 4,005 16,130
8 2,359 10,047
9
Totals 16,965 61,017
totals of seeds by the number of ovules in the locules in which
they were produced and summing at the same time we find
S(a’y’) = 400,920.
8 The method is applicable to graduated variates as well, since in the
process of calculation the centers of the classes are taken as integral.
°T use a Brunsviga. A comptmeter will serve well for this.
696 THE AMERICAN NATURALIST (Von. XLIV
To complete the calculation of the correlation r,,, we require
only As, As, oo, os. Taking the origin at 0 for both of these char-
acters’ and multiplying and summing at the same time, as
we did before, we get:
S(2z’) == 109,818, S(2/”) = 721,904,
S(y’) =61,017, S(y’*) = 284,287,
S(x’) | N= 109,818/ 16,965 — 6.4732 — Az,
S(y’)/N= 61,017/16,965 — 3.5966 = Ay,
o2— V §(2")|N—Az?—= .80629,
oy — V Sly”) | N— A,? = 1.95485,
— Sa'y IN—ArAy a993,
ay
Tay
Now I think, notwithstanding these large numbers"! there has
been a material gain in facility of* calculation. The writing
down of the indices showing the products of deviation has been.
entirely avoided. The direct calculation of the totals of arrays
is easy, and it is only one short step further to obtain the means
of arrays for testing linearity, either by the sensible agreement of
empirical and theoretical means, as shown by a graph or by the
application of Blakeman’s test to »?——1*. Note also that in the
conventional method of obtaining S(a’y’) there is no way of
checking the work except to go over it independently. In the
method here described the larger part of the work of obtaining
S(a’y’) is at once checked by the fact that the sum of the totals
of the y arrays=S(y’). The final multiplication and summa-
tion is very quickly verified.
There are advantages in the method beyond these indicated by
this illustration.
Suppose that one wishes to correlate between a first character
and a number of repeated characters and their sum. This some-
times happens in work on fertility. Take as an illustration a
table’? showing the relationship between the length of the fruit
and the number of ovules on the two placentz in the bloodroot,
2 Where the range is great it may pay to use the conventional method
in calculating the standard deviations. Of course it is quite immaterial for
the method of calculating r suggested here, how the constants of the two
variables are deduced.
“I have purposely chosen an illustration giving large numbers. The
series of observations with which we are dealing here is larger than is
generally available in biological work.
“Table IV, 1907, Biometrika, Vol. VII, p. 335, 1910.
No.527] SHORTER ARTICLES AND DISCUSSION 697
TABLE III
Length. Number of Total Ovules. Length. ok a-ha Total Ovules.
21-23 2 19 45-47 208 3,615
24-26 94 48-50 142 2,564
27-29 56 636 51-53 65
30-32 162 1,922 54-56 20 442
33-35 336 4,442 57-59 18 458
36-38 366 5,106 60-62 4 119
39—41 318 ,590 63-65 2
42-44 308 4,868
Total 1,000 29,904
Sanguinaria Canadensis. Table III gives the frequency and the
total numbers of ovules produced for each length-class.
S(a'y') = 1,217,367."
We now calculate the correlation for the length and ovules per
placenta or length and total ovules at pleasure. In the first class
we have
at 217, call ba — 39.703 14.952
=x, -+ 4
30704 X 4.61361 P oe
and in the second
tay APATION] Oe X DRAS
oo +. k
30704 X 9.05447 ES
Again, a worker may have the means and variabilities for two
characters p and q, and wish to obtain the correlation without
trouble of preparing a formal table. He simply seriates his cards
according to the p character, sums the values of the associated q
characters and writes down grades of p and the associated totals
in a table like II or III. The remainder of the work is as illus-
trated above.
Or, finally, in short series r may be very quickly calculated by
summing the product of the values of the two characters of the
individuals, dividing by the total number, subtracting the prod-
uct of the two means, and dividing the result by the product of
the two standard deviations.
13 This number looks rather formidable, but it is read directly from the
Brunsviga and can be verified in two or three minutes. Had we centered
the length at class 36-38 and the number of ovules at 20, and worked by the
conventional method we should have had to calculate and write on the cor-
relation surface nearly 200 of the products of the deviations of the x and
y characters from their assumed means. Some of these are rather large and
there is no way of checking the work except to go over it independently.
All this is obviated by the method suggested here.
698 THE AMERICAN NATURALIST [ Von. XLIV
The best illustration I have is from Apstein’s't work on Mysis.
Table IV shows the body length in millimeters and the number
of eggs and embryos for a series of 52 individuals taken Feb-
ruary, 1904, and Table V the same characters for a series of 24
taken at all other times in 1904 and 1905.
TABLE IV TABLE V
Length and | Length and | Length and oe A and Langth a and and | Longin an PEP
Eggs. | Eggs. Eggs. ggs.
13-9 16-17 18-23 20-66 12-27 19-25
14-9 16-21 18-24 21-26 14-20 19-26
15-11 16-23 18-35 21-34 14-21 19-35
15-13 17-16 18-36 21-48 14-28 19-51
15-13 17-16 19-26 21-51 15-11 19-77
15-16 17-16 0 21-51 15-17 20-16
16-13 17-18 5 21-58 15-4 20-27
16-14 17-19 20-30 21-62 16-11 20-47
16-14 17-23 20-39 22-24 17-12 21-43
16-16 17—26 20—48 22—47 17—24 22-15
16-17 17-28 20—49 22-68 18-13 23-36
16-17 18-22 20-51 22-71 18-17
16-17 18-22 20-58 23-67 18-21
The range of both characters is large. If one were to prepare
a regular correlation table (omitting all unnecessary columns
and rows) he would have tables of 341 and 222 compartments
for the 52 and 24 observations !
Multiplying out with the help of the first twò pages of Bar-
tow’s tables for the higher squares, we find for the first series:
S(a’) = 946; S(a’ ) = 17,516; S(y') = 1,623; 9(y”) = 67,089;
S(a’y’) = 31,432; N — 52 whence
r== [S(x’y’)_N— 18.1923 X 31 2115] / (2.4261 X 17.7768) =
For the second series S(x’) = 424; S(x") = 7,672; S(y’) = 665;
S(y'*) = 24,149; S(a’y’) = 12,018; N=—24, whence
r= [S(2’y’) | N — 17.6667 X 27.7083] / (2.7487 X 15.4420 = .26.
The professional statistician will note that mathematically
there is nothing novel in the methods suggested. But I have
“ Apstein, C., ‘‘ Lebensgeschichte von Mysis mixta Lillij,’’ Wissenschaft-
liche Meeresuntersuchungen, Abteilung Kiel, N. F., Bd. IX, s. 241-260, 1906.
give Apstein’s data merely as an illustration of a method of calcula-
tion. Not only are the numbers too small for biological conclusions of much
value, but the series are more or less heterogeneous, coming as they do from
several stations. Apstein’s own conclusion from his data is ‘‘Dass die Zahl
der Embryonen nicht so von Salzgehalt als von Grösse der Mutter abhängig
ist 7?
No.527] SHORTER ARTICLES AND DISCUSSION 699
found them a great service, and since I have never seen them in
uset by other calculators it seems worth while to direct attention
to them.
J. ARTHUR HARRIS.
COLD SPRING HARBOR, L. I.,
August 27.
In some respects Hardy’s summation method described in detail b
Elderton in ‘‘ Frequency Curves and Correlation’’ is similar, but I believe
that the one here proposed requires less labor.
NOTES AND LITERATURE
SCHLOSSER ON FAYUM MAMMALS?
A Preliminary Notice of Dr. Schlosser’s Studies upon the Collec-
tions made in the Oligocene of Egypt for the Stuttgart Museum, by
Herr Markgraf.—The most interesting points are the much greater
variety of Hyracoidea, including both bunodont and buno-
selenodont types, and the presence of true Primates, which the
author refers quite positively to the Anthropoidea. The fauna
is also shown to include Chiroptera and Insectivora, the one order
represented by the humerus of a large vampyroid bat, Vampy-
ravus, the other by a lower jaw, Metoldobotes, compared with
the somewhat problematical Proglires.
The Primates are represented by three lower jaws, Maripith-
ecus, Parapithecus and Propliopithecus, the two latter sufficiently
complete to indicate the dentition, which is typically primate,
although in the reviewer’s opinion the material is not adequate
to prove their reference to the Anthropoidea, still less to assert
that the last genus is ‘‘not only the ancestor of all the Simiide,
but probably also of the Hominide.’’ If the author had stated
that the Oligocene ancestor of man probably had lower teeth like
those of Propliopithecus, the conclusion might well be accepted.
But the corollary of Schlosser’s statement is that we have found
the Oligocene ancestor of man and that he lived in Africa. The
evidence is not adequate to warrant any such conclusions. Dr.
Schlosser has perhaps no intention of drawing them. But others
will promptly do so, and add a little more to the top-heavy and
ill-balanced superstructure of speculation and hypothesis which
obscures the little that we really do know about the ancestry of
man and, to a less extent, what we know of the ancestry of most
other animals.
The Hyracoidea are discussed at some length. Besides the
more typical Saghatheriide of Andrews, with bunoselenodont
teeth, Schlosser refers to here as a distinct subfamily, the prob-
lematical Geniohyus of Andrews and defines three new genera,
Pachyhyraz, Mixohyrax and Bunohyrax, intermediate between
the two extremes. Six new species are named, but without hint
of description. As the paper is avowedly published in order to
1 Uber einige fossile Siiugethiere aus dem Oligociin von Agypten,’’ von
Max Schlosser, Miinchen, Zoologischen Anzeiger, Bd. XXXV., Nr. 15, vom
1 Marz, 1910.
700
No. 527] NOTES AND LITERATURE 701
secure priority for the results of Dr. Schlosser’s studies over the
concurrent investigations of other authors, it is unfortunate that
other authors, however well disposed, can not accept his species
as of this date, without violating the rules of nomenclature.
Of more importance than questions of priority is Dr. Schlos-
ser’s estimate of the affinities of these Fayim Hyracoids. They
differ widely from modern Hyraces in the general form and
proportions of the skull (and are singularly like pigs and anthra-
cotheres—W. D. M.) but agree very nearly in the basicranial
foramina and jaw articulation, as also in the general construc-
tion of carpus and tarsus; the feet are, however, more specialized
(as might be expected in view of the larger size of the animals).
They are not directly ancestral to the modern Hyracide, but
Pliohyrax of the Pliocene of Samos is apparently descended
from Saghatherium.
The author regards the Hyracoidea as having no near rela-
tions with any other order except the Condylarthra, and as in
certain important features cited they are more primitive than
any known Condylarth, the relationship ean not be very close
even here. He disbelieves in the affinity to Arsinoitherium sug-
gested by Andrews, holding that this genus is related to the
Amblypoda. <Any relationship of the Hyracoidea to the Probos-
cidea through Meritherium must be limited to a common deriva-
tion from Condylarth ancestry. He agrees with Sinelair that
the Hyracoids have no real affinity with the South American
Toxodonts and Typotheres (which, eese can equally well be
derived from Condylarth ancestry—W. D. M.) and protests
strongly against the names given by POS to several South
American genera indicating Hyracoid affinities which Dr.
Schlosser regards as a baseless hypothesis. (But to name a
genus in indication of its supposed affinities, often subsequently
proved erroneous, is so common a procedure, that it is hardly
fair to condemn the Argentine paleontologist for following it.
The eight new genera named in this paper are every one of them
designated in accord with the author’s hypothesis as to their
relationship, and several of them at least may turn out to be
seriously misleading.—W. D. M.)
Among the Carnivora, two new species of Apterodon are men-
tioned, one of which is adequately described, and the prob-
lematie genus Ptolemaia Osborn is discussed and considered as a
highly specialized offshoot of Cynohyanodon. (The teeth of this
genus are very peculiar, however, and are more suggestive of
702 THE AMERICAN NATURALIST [ Vou. XLIV.
Insectivore or even Tæniodont affinities than of Hyznodont de-
rivation. They certainly can not be derived from those of Cyno-
hyenodon.—W. D. M.)
A united scapholunar bone is considered to represent a gi-
gantie undescribed Creodont ‘‘vielleicht eine Palæonictis oder
eine Pachyena.’’ (It does not appear, however, why Dr.
Schlosser should suggest the presence of these genera. In
Pachyena the seaphoid and lunar were certainly separate, nor is
there any evidence nor probability that they were united in
Paleonictis; both genera are of Lower Eocene age, and belong
to families of Creodonta of which no trace has been found in the
Faytim fauna or in the Oligocene epoch, and in which the seaph-
oid and lunar were never united, so far as we know; on the other
hand, we know that the Hywnodonts were represented by several
genera in the Fayûm and are the only Carnivora positively
known in this fauna; they are the only family of Creodonts
known to survive into the Oligocene, and in Hyawnodon, at least,
the scaphoid and lunar were sometimes united. The probabil-
ities, therefore, are greatly in favor of this scapholunar repre-
senting a large Hyenodont.—W. D. M.)
The presence of Chiroptera in the fauna is an interesting pos-
itive addition. The same degree of certainty does not attach to
the Insectivora, since the Proglires with which Metoldobotes is
compared are a group of somewhat doubtful boundaries and
affinities. If the Fayûm genus is really related to Olbodotes
Osborn (‘‘Oldobotes,’’ Schlosser) it is a point of some interest.
Olbodotes and the almost identical Mixodectes form a charac-
teristic group of the Basal Eocene fauna of North America. As
Osborn has repeatedly insisted, this fauna was not the source of
the later Eocene faune in North America, except for a few
groups like the Phenacodonts, Coryphodonts and Uintatheres,
which gradually disappeared through the course of the Eocene.
There is strong support for the hypothesis that it was the source
of the early Tertiary faunæ of South America which developed
in isolation along lines partly parallel with the development of
the great Holarctic fauna. The autochthonie element of the
early Tertiary fauna of Africa may be derived in a correspond-
ing manner, except that the isolation was not so prolonged or else
not so complete. The Cernaysian and Puerco-Torrejon faune
as known appear to be parts of the same regional fauna, the
Paleocene Holarctic. The derivation of Hyracoids, Arsinoi-
theres, Proboscidea, ete., from this fauna is conjectural because
No. 527] NOTES AND LITERATURE 703
we have no intermediate stages. But the discovery of less pro-
gressive and specialized descendants of Paleocene Holaretie ani-
mals in the African Oligocene would lend support to this con-
jecture. Unfortunately, Metoldobotes is referable to a group of
disputed affinities in which the dentition is a treacherous and un-
certain guide, the reviewer feels obliged to accept the reference
with reserve; but it is well to point out its significance if con-
firmed.
The rodent genera described by Osborn are wrd by
Schlosser as obviously related to Theridomys and Trechomys
of the European Eocene and Oligocene, the relationship being
confirmed by the discovery of an upper jaw. (Osborn compared
the originals with specimens of these and other European genera,
mostly identified by Dr. Schlosser, expecting to find the affinities
close; but the most that the evidence warrants is that they prob-
ably belong to the same family. There are genera of several
other families of rodents which approach the Theridomyid pat-
tern and dentition as closely as do Phiomys and Metaphiomys of
the Fayûm.)
The foregoing review may appear perhaps unduly critical.
But there is an increasing tendency in scientific work towards an
uncritical acceptance of the views and conclusions set forth in
the work of special research. It becomes peculiarly incumbent,
therefore, on those who are engaged in such work to avoid over-
positive statements or conclusions based upon inadequate evi-
dence.
Conservative statement and open-mindedness are essential to
the permanence of scientific theory. And from Dr. Schlosser,
who is justly regarded as one of the greatest living authorities
upon Tertiary mammals, we may fairly demand an exceptional
degree of conservatism. W. D. MATTHEW.
AMERICAN MUSEUM OF NATURAL HISTORY.
THE OPHIDIAN GENUS GRAYIA
Dr. C. B. Davenport, writing on the imperfection of domi-
nance, has recently remarked that ‘‘the weakened character
may be retarded in development so that it fails to appear at
the normal period but develops later. Thus Lang found hybrids
between red and non-red snails to be at first non-red but finally
red.? Some authors have spoken of this as reversal of domi-
* American Breeders’ Magazine, Vol. 1, p. 40.
2 Helix nemoralis var. libellulo-rubella; ef. Taylor, ‘‘Monog. L. & F. W.
Moll. British Is.,’’ part 17, p. 304.
704 THE AMERICAN NATURALIST [ Von. XLIV
nance, and even Bateson uses this terminology in his latest
book. But this is obviously an unfortunate term if domi-
nance means the presence of a quality. For, a given qual-
ity, that is due to the absence of a factor, like blue iris [of
the eye] color, can not be at one time recessive and at another
dominant. If a blue iris appears where brown is expected, the
clear reason is that brown pigment has merely failed to develop
and is potentially present. A similar case occurs in hybrids be-
tween albino and some buff birds; the chicks have a pure white
down, only later acquiring the black and buff of the adult
plumage.’’
Dr. G. A. Boulenger ë has recently published a very interest-
ing paper on Grayia, a genus of African snakes, in one of which
the pattern of the young appears to be completely reversed in
the adult. In the young of Grayia ornata (Bocage) var. furcata
(Moequard) the body is black, with broad whitish or greyish
cross-bands, which bifureate below on each side, so that in lateral
view the snake is ornamented with a series of reversed Y’s
Each Y is slightly speckled with black about the middle line.
As the animal grows, the black ground-color gradually changes
to grey or brown, owing I suppose to the increase in size without
any corresponding increase in pigment-production. The Y’s, on
the other hand, show more and more black, until they have only
a light edge, while in the adult even this disappears, and we
have then a series of perfectly black markings on a grey ground,
in place of similar light markings on a black ground. This case
is curiously suggestive of those cited by Dr. Davenport, and also
interesting as showing that the black markings of the adult are
not simply superimposed over the grey or brown, but occupy an
area which, but for the black would be pale. This reminds one
of the case of the English poppy, which has black spots on red
petals, but when the black drops out, as in the Shirley variety,
white spots appear. The condition found in the snake can hardly
be explained by the simple proposition that the animals are
heterozygous for the color of the markings, the black being
dominant. In this case, we ought apparently to find a certain
proportion of recessives, which would retain light Y’s to the last.
Possibly such oceur, but have not been recorded. It seems more
likely, however, that tardy development of a pure character here
simulates the behavior frequently found in crosses. Incidentally,
we may note also the suggestiveness of the case in relation to
the development of ocelli. T. D. A. CocKERELL.
* Proc. Zoological Soc. London, 1909, pp. 944-952.
The Anatomical Laboratory
of Charles H. Ward
189 West Avenue, Rochester, N. Y.
OUR HUMAN SKELETONS are selected specimens scientifically
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THE
AMERICAN NATURALIST
VoL. XLIV December, 1910 No. 528
HEREDITY OF SKIN PIGMENT IN MAN. II
GERTRUDE C. DAVENPORT anb CHARLES B. DAVENPORT
CARNEGIE INSTITUTION OF WASHINGTON, STATION OF EXPERIMENTAL
EvoLUTION, CoLD SPRING HARBOR, N. Y.
E. INHERITANCE OF ALBINISM
Albinism is the absence of pigmentation through lack
of either, or both, the chromogen and the oxidizing fer-
ment. The condition occurs widespread among animals
and plants. In man it is rather rare, probably not occur-
ring (if one may hazard a mere guess) in the population
of the United States, as a whole, in more than in one
case in 10,000 people.
Of true albinism in man there are all degrees. Aside
from the piebald condition occasionally found in colored
persons there are various grades of uniform depigmen-
tation—hair color varying from light yellow to pure
white; irides varying from pale blue to absence of blue,
and pupils varying in the intensity of the pink color.
Indeed, there is abundant testimony that persons born
as albinos may acquire a slight pigmentation. Such a
case was cited by Dr. H. B. Young (1905) from Illinois.
Albino cats also vary in the pinkish glow of the retina.
Despite variations in the completeness of depigmenta-
tion albinism can usually be clearly distinguished, at
least in its more marked grades, and so we can study its
inheritance. The cases given below were mostly col-
705
706 THE AMERICAN NATURALIST [Vou. XLIV
lected by ourselves alone, or with the aid of a medically
trained assistant, Dr. Sumner Everingham, and many of
the albinos were seen by us.
I. Born PARENTS ARE ALBINOS
1. Luc. FAMILY
= Sarg easoae: aa
albino | albino
l |
2 3
albino Joseph L.
albino
te.—This case is on the authority of Mr. Rob Roy, an albino who seems
aiies trustworthy, and has met many albinos in the ‘‘show’’ business.
2. PRI. FAMILY
ECE) = 9(-) arid rei a
eee Caucasian negro | negro
l ] |
3(C. P.) = 9(N. W.) 3
albino | albino black
albino
Note.—This case also on the authority of Rob Roy.
3. R. FAMILY
$(—R) = 2 (—)
| brunet
¢ (—W.) =? 4 (J.R) Po W.)
fai ir very hair
dark brown sandy
pigmented albinos 9 aw) (R.R.) os .R.) TPE Aalena.
albino albino hair jet
black
$(K.C.R.)
albino
Note.—R. R. seen by me.
No. 528] SKIN PIGMENTATION IN MAN 707
II. NEITHER Parent ALBINIC
(a) Albinos in Caucasian Families with Admitted Con-
sanquinity
4. SHE. FAMILY
g (—S8.) =9 (—) g (—F) = 9 (—
intermed. blond brunet brunet
H: brown®] H: yell. br. H: black | H: It. br
I: brown |I:blue_ - I: brown | I: blue
Ist gene tr) pi T i N i
d (J. S. )—=9 (—F or g Q
fatas = Ate i: light H: light H: br. H: golden
H: brown |H: dk. br. I: blue I: blue I: br. I: It. br.
i the ay I: brown
| | | |
g (J. 8:) 9 (F. S.)! g (M. 8.) 9 (M. B8.)
brunet albino blond brunet
H: black H: flaxen H: yell. br. H: black
I: brown I: light blue I: blue I: brown
5. ENN. FAMILY (IRISH ORIGIN)
= 9 ( wid, My == 90C. Dp.
H: ‘ihe yali k H: Shack H: yell. br. | H: black
I: d I: d IH. br. I; dk. br.
|] ] I
9 9 g (J. E.) = 9 (M. M -) $y =F l=
H: verylt. H: dk. fair-interm
n
brown brown H: tia - (+red) P ae a gre) several children; ER TA
I: b
i ae Se B| I I l] [ I | I
deceased ten Q g g Q g
pigmented albinos (C. ha, (A.E.) (F. E) (W. E.) (E. E.) (H. = M. D. Vik E.)
albino RT albino int’ toy int’rm’d. albin Pig- albino
i: white H: black H: white H: black H: black H: white n- |H:white
I: It. blue Pa rh I: It. blue gach ae I: pale bl. tel I: It. bl.
k. br.
‘hh i
of (F. E.)
H: brown
I: dk. br
Note.—Three generations known; no other albinos. The father and
mother, JE an , are distant cousins (not first); and father’s mother
and mother’s mother bear the same surname and come from the same place in
Ireland. The youngest son (JE) married a distant cousin having the same
surname as both his grandmothers. Seen by C. B. D.
®In the pedigree tables H indicates hair color; I iris color
1 Hair faintly yellowish; irides pale blue; retina, medium pinkish glow;
nystagmus moderate; congenital | school work satisfactory; father
and mother first cousins. Seen by S.
708 THE AMERICAN NATURALIST [Von. XLIV
6. Par. FAMILY
|
|
# (M. P.) = 9 (-) g (J. A.) = 9 (M. P.)
Aian NA VT
| ARAR | | | | oep tT ]
brunet ela
H: black H: black
I: blue
TON lar bore eee ie Sy 9 (S. P.) JP CE) of (J. P.)
H: black It.brunet albino lt.brunet brunet pigmen- brunet
H ‘Black I: ‘blue i H: black blond H: black H: black ted H: black
I: blu H: golden I: blue H:goldenI: blue 1I: blue I: blue
white white
l: pink I: pink
(b) Albinos in Families with Suspected Consanquinity
7. Sac. FAMILY
3 (G.8.) = 9(8.8.) E Er AP)
blond intermediate intermediate
H: golden H: brown : yellow br.
I: lt. blue I: dk. brown I: blue-gray
I |
9 (M: J.8.)? g (H. 8.) —
non-albinic blond f
H : golden H : golden
I: med. blue 1: medium-blue
I !
3 (G. 8.) ? (H. 8.) ? (©. 8.)
blond albin
H: lt. golden il: eat yellowish H: silvery gold
1: med. blue I: no blue I: no blue
Note.—Seen by C. B. D. and S. E. + and ? have iha same middle name.
* and * show reddish glow through pupil.
(c) Albinos in Caucasian Families with no Evidence of
Consanguinity
8. Don. FAMILY (IRISH ORIGIN)
d (0. D.) = ¢ (E. G.)*® o (8. C.)*= 9 (D. C.)
H: dk. br. | H: brown H: flaxen | H í chestnut br.
I: blue I: blue I: blue : blue
a | | [i p |
F (A. D) = i (E. C.) 3 of ons 12 Kiori ad
blond intermediate sisters have red hair
H: brown; | H: It. gold.
beard sandy brown
I: blue I: blue
j | I 1
d (A. D.) = 9 Q (A. D.) gS D)=¢ Q (M. D.)
albino H: dark golden br. H: very It. gold. br. albino
= rers : blue I: light blue H: white i
i ue, b
k str I: light blue,
pupil pink
No. 528] SKIN PIGMENTATION IN MAN 709
Note.—Seen by C. B. D. No relative on either side known to be an albino.
9, Ep. FAMILY
7) = 9. (—)
intermed intermed
H: brown H: chest. br.
I: brown I: gray-blue
of (B: v1)
brunet intermed
H: db H : chest. br
I: brown lue
l Í
3 (B. E.) S a 9
albino H: chest. br. intermed. brunet
H : flaxen white I: blue H : chest. br. H: black
I: no blue I: blue I: brown
Note.—Seen by 8. E.
10. Far. FAMILY
A Gare pee = 9 (—) de- bo )
intermediate brunet brunet intermed
H : chest. br. H : brown H: dk. br. H: chest. br
T: blue I: brown I: brown lue
| [ | l | I
9 d g g d (W. A.F.) = TER 9 (J. L.)
Heekat br H: a brown intermediate ARE A H : dk. br.
i oT ON: Wo : chestnut : brown I: brown
I: chest. br. I: eiaa
|! l
d' (H. F.) 3 (R. F.) 3 (E. F») (S. F) 2 W. F. AR
intermed. intermed. intermed. med. med.
H : chest. br. H : — er H: chest. br. H. oku. br. H. Toho: br. H hike
I: aon I: bro I: brow I: brown I:brown _ I:pale blue
8 Some relatives with sandy hair.
? Many of his relatives have red hair.
1 Hair white as snow; retina with bright pinkish glow; nystagmus
moderate; shortsighted; can read 9 pt. Modern (Roman) type at three
inches from eyes; school work middling. Red hair in ancestry, three genera-
tions back.
“Seen by S. E. Retina, medium pinkish glow; nystagmus slight; reads
No. 9 Modern (Roman) print at nine inches; schoo] work satisfactory. No
consanguinity known.
710 THE AMERICAN NATURALIST [Vou XLIV
11. Fer. FAMILY (ITALIAN)
fs) =9F) s(—-) = 9 C)
Wize . I: black H : black H: light br. H: black
I: black I: light gray I: dark br.
m
3 (¥. Fe) = 9 (A—)
H : brown H : black
I:blue +a I: dark br
little brown
| { 1 |
g (A. F.) Q O O
albino
H : white H : brown H : light br. H: brown
I: blue I: dark br. I: blue I: dark br.
retina pink
Note.—Seen by C. B. D. No consanguinity so far as known. No other
albino relatives recalled.
lla. Ho. FAMILY (BOHEMIAN)
g = 9 g Q
H: brown | H: lt. br. 3 ARE ar H : brown
I: brown I: blue : blue I: blue
| l
fof = Q
H: lt. br. | H: brown
I: blue I: blue
eyes crossed and weak in sun
Í
öv. H. g i E. H. a son (which?)
albino albino s cross-eyed.
12. Hor. FAMILY
o'(—H.) = 9 (L E) g Q
H: med. br.| H: dk. br. H: light as child | H: dk. br
I: gray I: dk. br. v. dk. br I: blue
I: brown
i |
o (J. E. H.) = 9 (8. M)
H: dk. br. H: chestnut
I: gray I: brown
$ (G- B.) 9 (D. H)
I |
Q(C.L.H.) $ (V. H.) 9 (E. H.) g (A. H.)
low H: yellow as H: per as albino
H: silver- H: yellowas H: yel
white child; I: blue child U o 5 = a
as child; dk. br. I: blue t. br white
It. br. I: brown I: blue 10 cost
I: blue eee ;
yellow
I: very It. DLs
pupil pink
Seen by C. B. D. Nystagmus present.
No. 528] SKIN PIGMENTATION IN. MAN LIE
13. Hur. FAMILY (GERMAN ORIGIN)
l |
d H.) = 9 C) PI 8 C7 $.
brunet ~ brunet brunet blond H: light
H: black | H: brown H: black | H: yellow I: blue
I: brown I: brown I: brown | I: blue
l |] | |] | i
Q Q Q o(B.H.) o&(8.H.) = 9
H: dk. br. H: dk. br. H: dk. br. H: black brunet
brunet
I: blue I: blue I: blue I: blue H: brown | H: dk. br
I: brown I: brown
| |
9 (SIL) BOM.) & (LHL) ọ D. H 9 9
hake net bino inter med. brun brunet
H: dk. br. H: black FE faint yel. H: haan H: ak. br. H: brown
I: brown I:black I: med. blue I: rows: I: brown I: brown
14. Liz. FAMILY
ay = S L a,
brunet unet
rown H : brown H : brown
I: brown I: brown
I
PLEJ = 9 (E L)
brunet
1: flaxen H : black
I: blue-gray I: dk. br.
of (B. L.)
aw Be
whit
I: “pale tine
Seen by S. E.
15. Moe. FAMILY
PIN M.) = ¢ (A. M.)
blond interm.
H: It. br. H: dk. br.
I: It. blue I: chest. br.
g
albino’
Ts fjorda
Seen by 8. E.
Retina with slight pinkish glow; nystagmus present in moderate degree;
i er hypermetropia.
a pigmented; nystagmus present; nearsighted.
aa aka pinkish; nystagmus present; very slight internal strabismus;
general Fe Pa average at school work, reads readily; sight good except
in bright light
712 THE AMERICAN NATURALIST
16. McK. FAMILY
fof mate
brunet intermediate
H: brown : chestnut brown
I : brown I: blue
1 ] |
Q of ae
albino albino!® intermediate
H: dark brown
I: blue
Seen by S. E.
17. Moo. FAMILY
= ọ on — 2 3
dark dark intermediate | intermediate
l: blue | I: blue H: light br. : black
: I: blue
ou 9
rune intermediate
H : black H : chestnut brown
blue I: blue gray
| I
intermediate | albino!” intermediate
: dark br. : dark brown
I: dark br. I: dark brown
. g ° |
intermediate
H : brown
I: dark brown
Seen by S. E.
18. Nea. FAMILY
g
H : yellow; red | H: black
I: hazel
I: brown
|
f light b H light red
: ight brown : very light re
I: blue I; J
blue
|]
2
albino! (M. N. A.)
3 :
at? jet black
I: sky blue
* Hair white; iris pale blue; retina pinkish as seen through pupil; nyst
mus present; slight internal strabismus; work at school very difficult, sight
k
growing weaker.
1 Details as
above. Eyes stronger, can read No. 9 point at 18 inches.
“Hair white; iris light blue, retina dark (almost black), nystagmus
present, has congenital high degree of myopia. Fairly good at school, can
see to sew at night, bright in conversation.
* Complexion very fair, hair white, iris clear blue.
[Vou. XLIV
No. 528] SKIN PIGMENTATION IN MAN 713
19. Nog. FAMILY (ITALIAN)
fot = Q rol Q
Donne int Te intermed. intermed
H: bro H : bro H: brown | H: brown
Ts Sach I: “cet I: brown I: brown
I
J (B. N.) = 9 (A.
intermed. a Soot
H: chestnut | H: dk. br
I: brown I: bro
g (F. N.) 3 (C. N.) Q (E. 1 N.) oe. $ (F. N -) 9 (M. N.) g (A. N.)
H: brown albino wn H: brown albino
it: hike I: brown H: Sio i esbis ir rises wn I: “abe H: whit
‘eye pink? ‘eye pink’’ “eye pink”
20. Rip. FAMILY
intermed. intermed. Macy net
H: brown H: brown : dk. br. | H: dk. br.
I: gray blue| I: gray blue I: brown I: brown
E l | | l | l l l l l |
Q Q A O E o o = g F Q ge Q
(E.L.)(M.R.) (R.H.R.) |(E.C.R.)
TA TA TA TEA TA oe EE TERE TE TETE TA
Zo Fo Zy Zu Fa Fa So8 | Fok Fa Fa Fa Fo
Bo Er SE Sk gF oF HPs egg 5. 2 SF SF
Poe os sf sf se | BS m RERE eR
| I l
g E. o g =g 9 =
H:lt.br. albino’ albino” | H: dk. br. Albino” iane. H: sandy
I: blue I: brown H: br. | I: blue
I: Maam
I l l
g' Q of fe) O
H: dk br: H:dk.br. H: dk pr. pigmented
I: blue I: blue I: blue
Seen by S. E.
21. THo. FAMILY
l |
=O O =0
O d (@.T) =?
albino albino blond H: dark
EBS EN ae ti Jei d
O (0)
4 albino 5 pigmented
* Hair, faintly yellowish; iris, devoid of blue; retina with medium pinkish
glow; nystagmus moderate; myopia, school work satisfactory ; read a good
m sparetime spent in weaving seats of cane chairs
air faintly yellowish ; iris devoid of blue; wiis with medium pinkish
glow; nystagmus moderate; myopia; school work middling.
* Hair faintly yellowish; iris pale blue; retina with medium pinkish glow;
nystagmus moderate; myopia; school weit middling.
714 THE AMERICAN NATURALIST [Vou. XLIV
22. WIL. FAMILY
g = =
interm. interm. brun
H: sandy | H: sandy H: jet stad H: Shes
I: blue-gray I: black I: light ee
—— m
= Q
interm. interm
H: It. b H: dk. br
I: blue I: blue
l | | |
of of Q y
albino” interm. interm. interm.
H: chest. br. H: lt: br. H: chest. br.
I: blue I: blue I: brown
Seen by S. E.
23. The P-W family. The relationships of the mem-
bers of this family, so far as worked out, are shown in
the diagrams 23a, 23b, 23c and 23d. The persons in these
diagrams come from the same general region and sev-
eral surnames are common, especially those indicated by
the initials P and W. The frequent recurrence of the
same four surnames in the paternal and maternal sides
of the ancestry of most of these albinos is testimony to
a wide spread consanguinity. Further details are re-
served for a later paper when it is hoped the pedigrees
can be extended and connected.
(d) Colored Families
24. MER. FAMILY
blond
H : light yellow-brown
I: blue
|
o' (M. R.) oJ. R. a 1. M.)
H: light blond H: dk. red or auburn
H: jet black
I: gray
9 (M. M.)
partial albino?
white
skin
H : light reddish-brown
I : blue
2 Hair white; iris pale blue; retina bright pink; nystagmus marked;
eyes sensitive pi bright light, sees better in half light. ‘‘Kept up with the
rest in school.’
* Seen by C. B. D. Retina not pink. Slight nystagmus.
No. 528] SKIN PIGMENTATION IN MAN 715
25. MAN. FAMILY
o(—M.) = 9 of .) =Q
(4 negro) ( white) (Indian ) (4 negro)
copper color | intermediate H: black | H: black
H: brown H : brown I; I: brown
I: brown I: blue
1
J (E. M.) =- O(A. M. P.)
intermediate copper color
: brown AL: black
I : blue I: black
3 | |] l l : | |
g g 9 w 9 (0.M.G. juo g
dark albino albino albino albino albino apeo. interm. brunet
mulatto H:
white White white aiii I: Taek black black
twins I: col- I: col- I: col- I: col-
orless orless eat orless bowi ince
Seen by S. E.
25. Under this head may be cited the observations of
Dr. Hrdlicka, who has collected data concerning ten al-
bino Hopi Indians and two albino Zuni.
It appears from his data that ‘‘albinos marry full-
colored individuals of the opposite sex. They seldom
raise any children and never have large families of their
own.” All of the albinos whose data follow have a pink-
ish-white skin and gray-blue or blue eyes. The color of
hair varies from flaxen to light brown.
A summary of the data relating to inheritance of al-
binism is given in Tables a and B.
TABLE a
GIVING THE COLOR CONDITION OF THE FRATERNITY OF EACH ALBINO DE-
SCRI THE PARENTS ARE, IN ALL CASES, OF NORMAL COLOR.
a R Number of Fraternity. || x i Number of Fraternity.
0. x. 0. X.
Normal. Albinic. || Normal. Albinic.
|
1 Q 2+? 1 | 7 Q 4or5 1
a | Belted a ss
| 1 1
4 F 3 s o 40 F 3 1
5 F á i n x 7 1
6 9 4 2 | 12 d 4 2
| Total 37+or | 14
| 38+
* Retina pinkish; nystagmus present; myopic; can read nine point print
at five inches.
716 THE AMERICAN NATURALIST [Von. XLIV
TABLE B
GIVING THE NUMBER OF NORMAL AND OF ALBINIC ies OF AN ALBINIC
INDIVIDUAL MARRIED TO A NORM
N, normal; A, albinic, D, the dominant rating R, the recessive.
D R DR (=N) RR (=A)
NQ A 467% 0 0
No C AYO 0 0
No A99Q 1 0
NQ Allg 1 0
| : | 2 0
If we consider both parents of the fourteen albinos
listed in Table a as simplex in pigment, i. e., as having
not only normal but also albinic germ-cells, they were
‘*DR’s.’’? When two such simplex (DR) individuals are
mated, we expect 25 per cent. of the offspring to be
duplex (DD), 50 per cent. simplex (DR or RD), and 25
per cent. without pigment (RR). Only the last will be
albinic, 75 per cent. will be of normal color. We actually
find that with fourteen albinos there are associated in
their fraternities 37 + or 38 -+ normal individuals, ex-
pectation being 42. The deficiency would doubtless be
accounted for by the unincluded normal children. Since
the proportion of albinic offspring in the given fraterni-
ties accords with expectation on the assumption that
albinism is recessive that assumption is justified.
Second, if albinism is recessive, it should not appear
in offspring of albinos with normal consorts. Unfortu-
nately the sterility of the cross makes it difficult to get
the desired data, but so far as they go, they are not in
disaccord with hypothesis.
Ill. Onze Parent ÅLBINIC
26. Epp. FAMILY
rol = Q
normal? | normal?
l Í
F = Q 9
pigmented | albino albino
|
‘all ED O ORLI
* These numbers refer to the serial numbers of the cases as given in
Table a.
No. 528] SKIN PIGMENTATION IN MAN 717
27. ENN. FAMILY oS or No. 5)
= E D:)
: black
Tid
ete
k. br.
a
H: brown
I: dk. br.
28. MAN. FAMILY Papert or No. 24)
x LAG M. G.) =
mented Caucasian
is brown
I: brown
O
albino
+ 5 yrs. old
29. Moo. FAMILY (CONTINUATION OF No. 17)
SRF
Mi P(E H.
albino intermed.
H: dk. br.
I: brown
fou
intermed.
H: brown
I: dk; br:
30. NEA. FAMILY (CONTINUATION OF No. 18)
Q (M.N. A.) Xo
albino pigmented
i] I
kA Q
lt. br. H: brown H: blond H: jet
lt. blue I: blue I: blue black
Q—|
I
2
H:
i:
31, Ri. FAMILY (CONTINUATION oF No. 20)
Heer ford a a are
Se
H: lt. brown H: pinti
I: gray blue I: brown
| | ] 1 l
(ot Q = d 2 Q
interm. albino albino H: dk. br. albino interm.
H: lt. br I: brown H: dk. br.
I: blue I: brown
718 THE AMERICAN NATURALIST [Vou. XLIV
IV. Tue D. G. V. Famtity (see Plate)
This remarkable family comprises a great mixture of
white, negro and even Indian blood, as well as many con-
sanguineous marriages. The Man family comes from the
same rural community, but its connections with the D.
G. V. family have not yet been established. It will be
observed that every albino has the blood of all three
families D., G. and V., so it can not be said, at present,
from which family albinism originally came. It will be
noted, also, that both of the youngest family (whose his-
tory is best known) arise from cousin marriages. Con-
sidering only those families in which albinism actually
occurs there are 8 albinos in 22 children, which is a
greater proportion than the expected 25 per cent. (5 or 6
albinie offspring). It is clear, however, that it may well
be that there is potential albinism in one or more of the
families with 3 to 5 children, in which by chance it fails
to appear—the 22 children are merely a minimum.
Details about some of the persons in this family follow:
V. 7, Yellowish complexion, brown hair and iris.
V. 8, Yellowish complexion, light brown hair, blue iris.
V. 9, An almost white mulatto, very light brown hair,
blue iris.
V. 10, An almost white mulatto, brown hair, blue iris.
VI. 4, Intermediate complexion, light brown hair, gray
iris.
5 VI. 5, Yellowish complexion, light brown hair, blue
iris.
VIL. 1, T. V., aged 3, albino, hair white, iris colorless,
retina with pinkish glow, nystagmus present, intellectu-
ally bright and well developed.
VII. 2, F. V., aged 4, intermediate complexion, hair
and iris dark brown.
VII. 3, M. V., aged 1, brunet, hair and iris black.
V. 20, J. V. (Indian, French and negro blood), yellow
skin, very light brown hair, yellow iris.
*« The Roman numeral refers to the generation; the Arabic to the
individual.
719
SKIN PIGMENTATION IN MAN
No. 528]
ITH 1q’}səyə N N gaq | Apues sees Apues 19 aq'{p 14 Iq'H "EM ‘gZ
— — — — = = ot oe a yaup T por | oqp “IZ
aq aqp aq aqp 14 Awad) qq Avs) q aq qq 4 £83 iq’, | “PIM “02
Iq N 19 qysty N N en[q 431 14 aqp N N “Ud 86I
1q aq aq 1q aq 1q aq qq . aq aqp aq səyə ‘BON ‘61
q N pze pər pA ae wee wa -x 19 port “4] A 14 qH ‘BON ‘ST
4 N 14 Iq'H 14 Hr 14 = Avis']q | aq'4səyo 14 N OW ‘LI
eae a se — eRe ber Be = 14 1q'}səqə aq aq PW “OT
oe pek = SUKI Iq'H q 1q"4] Iq Aq*yseyo aq'{p 1441 qH | “SOW ‘eT
Iq aq Iq aq aq aq q xep aq'{p N Aeq xep OFT Ft
14 E GZ aq N aq aq lq N aq Iq'{p aq aq ‘nA ST
14 aq"4p 1q Iq`IP 0} “9, Iq'APp 1q‘3p ABIB Iq 1q qseyo Awa aq'{p OH ‘ZI
14 aq 14 aq aq q Iq H 1q 14 aq 14 aq ‘OTH “STI
Iq'Hp N ALIS} 19°41 N N aee N Iq'{p N 14 aq ‘OT ‘IT
14 1q"4s0q9 Iq 1q'{p Iq aq 14 1q'}səyə aq 1q Iq'}səqo | ysoyo | ‘meg ‘OT
Iq £813 aq*ysoyo anA = 1q 1q qq N 14 aq"jsoyo aq N ‘PH ‘6
14 Iq*jsayo 1q xep 19 1q 14 1q’ Hp 19 "AQpjos"3] 14 Ut+iq uoq ‘g
— — oe m = oie se = 14 aq°1P N | AqQ'4p zog “By
adq | aq'yoA N N wap | q| 4H p103 1q pros 14 plod ‘oeg A
aqp N Iq"9] Aq*][a4 a1q'Jp N ITAP | IQ HOLH qp (U+)N aq U+tN| ‘uug ‘¢
‘14 qH 1q N 4 (q4 1q aq aq 1q°4p 1q 1q ous p
eh JWH "sÁ ‘HeH Any ‘IH akg "H ‘sÁ ‘JWH ‘sÅ H
‘WEN ‘ON
WN ‘TW Wu ‘Wa “IOTJOW “LOY OT
XI WIAViL
SLNAUVY GALNANOIA WOLA ONISIYV SONIATY JO SINAAVAANVAY ANV SLNIUVG JO AOIOQ AAW ANV UVH AHL ONIMOHY
720 THE AMERICAN NATURALIST [Von. XLIV
V. 21, M. (Irish origin), brunet, black hair, blue iris.
VI. 10, J. V., Brunet, brown hair, blue iris.
VE US G., Tntepmediate complexion, brown hair
and iris.
VII. 15, A. V., Aged 18, albino, white hair, colorless
' iris, retina pinkish, nystagmus present, mentally quick.
VII. 18, L. V., Aged 24, albino, white hair, colorless
iris.
V. Tue Connon oF Hamr and Eye COLOR IN THE Pic-
MENTED PARENTS OF ÅLBINOS
Assuming all pigmented parents of albinos to be sim-
plex in pigment we may inquire if such simplex parents
differ from the population at large in their hair and eye
color. To get an answer to this inquiry Table IX has
been drawn up.
This table is summarized in Table X, so as to bring
out the relative frequency of the different types.
TABLE X
THE RELATIVE FREQUENCY OF THE DIFFERENT TYPES OF HAIR AND EYE
COLOR IN THE PARENTAGE OF ALBINOS
Hair Color. Eye Color
Types. F. M.| FF.| FM MF. MM Total Types. FIM. |FF.| FM.| MF. MM. Total
ef |j u] m) m) l —| — | — |
N (black) | 3 2 3} 3| 3) 5! 19| N (black)| 2 ai. 2 6
dk. br. 2} 8} 1} -1) 2} 2] 16} dk. br. 3 3 2 8
br. 03S 6i 10) 4) 3) 31) be GO tr B 7535 32
elt. br. 4 rA Ti 1G. pe. 21 1 1 4
golden E a We eee a pee P 8| chest. br. | 1| 1 2
yello 1 1| hazel 1 1
flaxen 1 1 T 3| gray 1 1 1 3
3E 1} 1 2| blue-gray | 2| 1| 1 2 8
red+dk.br. 1 | | 1| blue a Ol Ot 4i éi T; 87
chestnut 2) 4, 1 3| 10} It. blue 1 1 1 3
red | 1 a 3
- Total 21 21 14| 15 14 16| 101 | Total 20/20} 15| 17| 16| 17 | 105
If Table X be compared with the proportional dis-
tribution of the different types of hair color in the pop-
ulation at large, certain differences are seen. Thus while
black, dark brown and brown hair constitute in a random
No. 528] SKIN PIGMENTATION IN MAN TPA.
population (Holmes and Loomis, 1909, p. 55) 695 out of
853 persons, or 81.5 per cent., in Table X, they consti-
tute only 65 per cent. On the other hand, while, accord-
ing to Holmes and Loomis (1909, Table IIT), red and
auburn constitute only about 5.5 per cent. of their popu-
lation, the various forms of red constitute 16 per cent. of
the population of Table X, or three times the typical
proportion. It appears then that, on the whole, the pig-
mented ancestry of albinos shows an excess of red and
the weaker grades of melanic pigment.
The distribution of eye color, on the other hand, shows
little that is abnormal. The ‘‘blacks’’ are somewhat
deficient, about 70 per cent. as abundant as in the popu-
lation as a whole, the browns are in excess, and the blues
occur in nearly normal proportions. The last result was
hardly anticipated as it might have been expected that
the pale blue iris of the albino would be specially apt to
proceed from blue-eyed parents, but this is not so. As
a matter of fact, dark brown eyes are quite compatible
with recessive albinism as Table XI shows. The general
teaching of Table XI is that the heterozygous or simplex
pigmentation of the offspring is not always clearly less
than that of the darker parent. But, on the whole, blue
iris predominates slightly and the hair tends to run
TABLE XI
SHOWING THE HAIR AND IRIS COLOR OF THE OFFSPRING OF AN ALBINO AND A
PIGMENTED PARENT
Parents. Offspring.
Family. Pigmented Parent.
Albino. Hair Color. Iris Color.
Hair Color. Tris Color.
Enn. g N dk. br. br dk. br. `:
Moo. Q dk. br. dk. br. br. dk. br
Nea e] pigmented pigmented It. br. lt. br.
br. blue
blond blue
jet black =-
Rid. Q dk. br. br dk. br. blue
dk. br. blue
dk. br. blue
422 THE AMERICAN NATURALIST Von XLIV
lighter than, or at least not to exceed, that of the darker
parent.
VI. THE ORIGIN AND ‘‘ CAUSE?” OF ALBINISM
The question remains to be discussed: What is the
origin and ‘‘cause’”’ of these albinos. The general con-
clusion seems justified, as in other mammals so in man,
albinism is due to the fortuitous union of two germ-cells
lacking this factor so that it is absent in the zygote
whence the albino proceeds.
The objections to this view are three: (1) The usual
absence of any history of albinism in the family; (2) the
improbability of so frequent unions of two persons bear-
ing albinism recessive; (3) the lack of statistical accord
of the results of human breeding with those of animals.
The first objection is not valid for any one who has
done experimental breeding, because he knows full well
how the recessive condition may be carried unexpressed
in the germ-cells for many generations awaiting that
chance conjugant that also carries the recessive condi-
tion. Absence of any history of albinism in a family has
the less significance in a country like ours where a large
proportion of the population can not tell the names of
their grandparents and know little of their cousins, who
may, indeed, live one to three thousand miles away.
The improbability of so frequent unions of two or
three persons having albinism recessive has been re-
ferred to by Pearson. With a mathematical showing,
he tells the story of an albino who married successively
two pigmented (?) husbands and had some albino chil-
dren by each. ‘‘All three stocks, according to Mendelian
hypothesis, ought to have albinism in a recessive form.
You can calculate the chances against that because an
albino occurs in Italy about 1 in 30,000, in Norway, about
1 every 20,000 of the population, in Scotland, 1 in 24,000.
What are the chances that a woman of albinotie stock
should marry two stocks affected with albinism and not
related either to her or to each other?” The inference
No. 528] SKIN PIGMENTATION IN MAN 723
seems to be that Pearson would be content with ‘‘caleu-
lating the chances’’ and, because the ratio was small, in-
sisting that the three stocks could not all have albinism
recessive. Such a method of procedure is, I fear, all too
characteristic of the ‘‘careful work’’ which alone, ac-
cording to its editor, is admitted to the pages of Bio-
metrika.” Of course the facts are that we have here no
data for calculating the required chances. In the first
place, the term ‘‘not related’’ has only a relative signifi-
cance in the statistics of human qualities; it usually
means not first cousin or nearer relative, more rarely
extends to second cousin, or at the outside, to third
cousin. And yet two persons of the grade of tenth
cousin may easily carry recessive an albinic condition
derived from a common source. <A fairer question
would be, what are the chances that a woman shall
marry in succession two men related between the grades
of third and tenth cousin, supposing, further, all three
come from the same rural district, long settled and rela-
tively stable? I think the conditions that Pearson does
not cite might easily render the chances several million
to one in favor of the three persons being less distantly
related than tenth cousin. An actual illustration of this
condition of affairs is shown in the D. G. V. and P. W.
families. The three family names represented by D.,
G. and V. occur again and again in this family, as the
pedigree table shows. Some of the consorts are recog-
nized as ‘‘first cousins’’; but in most other cases they
are stated to be ‘‘unrelated.’’ If the inquiry is pressed
the admission is made ‘‘were perhaps distantly.’’ One
may ‘‘caleulate the chances’’ that in the same mountain
community, of perhaps 300 inhabitants, who are all
segregated by color from the surrounding population,
two persons of the same name (uncommon outside the
community) are absolutely unrelated, or unrelated out-
side the degree of seventh cousin. But even in a flat
*In justice it should be added that the remark was not made in
Biometrika,
724 THE AMERICAN NATURALIST [Vot XLIV
country, penetrated by a railroad, we find, as in the
P. W. family, a large proportion of consanguineous mar-
riages. The argument against the probability of unions
with recessive albinism has not yet been presented with
any force.
The third point—the lack of statistical accord between
the results of human breeding and those of animals—has
been often remarked upon. ` Bateson (1909, p. 28, foot-
note) believes the descent of albinism in man to bo com-
plicated by some unascertained disturbance. A careful
consideration and analysis of the statistics indicates, I
think, that this disturbance is to be found in the method
of collecting the statistics. From the matings of two
persons that are simplex in pigmentation, two sorts of
families are to þe expected, namely, those with albinos
and those without. Since in the long run, from such
parents, only one albino is produced in four offspring, it
is clear that the chances are that in all families of one,
TABLE XII
GIVING ALL FAMILIES CONTAINING ALBINO OFFSPRING FROM TWO PIGMENTED
CAUCASIAN PARENTS
¿ Offspring Offspring
a g mA E as
Prt Fe ee
a eS ye Ee lee 5 a ig TE
< z= E4 q = ad
She. 2 3 4 25
Enn. T rA 14 50 Tho. 4 4 9 60
Sac. 2 1 3 67 papi 1 3 4 25
Don. 2 2 + 50 } 11 12 8
Ed. 1 3 4 25 EWA a. “IIL. 15 5 3 8 62
Far. 1 5 6 17 P-W.b. II. 2 2 rá 9 22
Fer, pd 3 4 25 P-W.b 3 1 2 3 33
Hlo. 2 1 3 67 P-W.c. I. 1 1 0 1 —
Hor. 1 5 6 17 VI 1 3 4 25
Huf, 1 5 6 17 P-Wad. III. 11 1 0 1 —_
Lie. r 0 1 -W. IV 1 12 13 7
McG. 1 0 1 POVL I 4 1 5| 80
McK.| 2 1 3 | 67 D.G.V. IV. 1 2 3 33
Moo, 1 1 2 50 D.G.V. VI. 10 2 8 10 20
Nea. 1 1 2 50 D.G.V. V. 24 1 3 -4 25
Nog. 3 4 7 42 Men. 1 0 1 —
Ria. 3 2 5 60 Man. 6 3 9 67
| Totals. 64 | 107 |171| 374
No. 528] SKIN PIGMENTATION IN MAN 725
two or three children albinism will not appear. Even in
families of four or more the possible case of albinism
may fail to occur. All such cases of an actual low ratio
of albinism are omitted from any calculation of propor-
tions; chiefly the accidentally high ratios are brought
under consideration. The actual proportions of albinos
to all offspring of two pigmented parents are given for
each family in Table XII.
These 33 families together with two not plotted in the
diagrams are summarized in Table
TABLE XIII
THE PROPORTION OF ALBINOS IN ALBINIC FAMILIES OF DIFFERENT SIZES,
WHEN NEITHER PARENT IS ALBINIC
Total
jcailaren fee} ee Families. Number of
Fam i Families.
1 1 100 Lie., Meg., P.W. (bis) 4
2 1 50 Moo., ts 2
3 2 67 Sac., 3
3 i 33 Vin. De = V P.W. 3
4 2 50 Don 1
4 1 25 She. Bags Fer., Gur., Wil., D.G.V., 7
5 4 80 ne Ls 1
5 3 60 Ria. 1
6 2 33 Wes 1
6 1 17 For. 3
T 1 14 P. W. pak bacon f
vi 3 42 Nog 1
8 5 63 PW 1
9 6 67 Man 1
9 4 Tho 1
9 2 23 P.W. 1
10 2 20 D.G.Y. 1
12 1 8 P.W. 1
13 7 54 Enn. 1
18 2 8 P.W. 1
35
Taking Table XIII in its entirety there is an average
of 44 per cent. albinos to a family where expectation is
25. If we consider only the families with four or more
children we find the average proportion of albinos to be
34 per cent.. If we take families with six or more chil-
dren the average proportion of albinos falls to 32 per
726 THE AMERICAN NATURALIST [Vou. XLIV
cent.; with 10 or more children to 23 per cent. On the
average, with the larger families the proportion of al-
binos tends to approach expectation.
A second source of error is not to be neglected. When
the attention of the parent or acquaintance is focused
by the questioner upon albinos the albinic children are
all recalled, while some normal children (such as were
still-born or died in infancy) are more apt to be for-
gotten. I have repeatedly had the experience of bringing
to mind by further questioning children that had not
been at first mentioned, and they were always normal
children. The records of families with only one child
and that an albino are frequently due to the fact that the
peculiar child is the only one recalled. Considering the
high frequency of infant mortality the omission of nor-
mal children forms an important factor tending to raise
the proportion of albinos.
A third possible source of error lies in imperfection of
dominance, i. e., the occasional failure of the pigment to
show itself in the young chlidren who have it simplex.
Of this imperfection there are all degrees. Thus
the albinos in the Lim (No. 14) and Moo (No. 17) families
have a dark retina with white hair, washed-out blue iris
and nystagmus. In other cases, such as the Rip family
(No. 20) and P-W,a (XII, 24, 25), the hair is yellowish,
while the retina is pink, or the pinkish retinal glow and
nystagmus may be slight. Another fact that favors the
view of frequent failure of the simplex determiner to
activate fully is the progressive increase in pigmentation
shown by some albinos. This is a common phenomenon.
Seligsohn in Eulenburg’s ‘Real Encyclopadie,’’ 1880,
p. 162, states: ‘‘Bei einem vongesunden Eltern mit allen
Merkmalen einer Albino geborenen Kinde schwand die
rothe Farbe der Iris von Jahr zu Jahr.” This increase
in development of a simplex character has been observed
by Lang in snails, by one of us in poultry and by others.
In concluding this discussion of the causes of the aber-
ration in the proportion of albinos I wish to urge that
No. 528] SKIN PIGMENTATION IN MAN 727
what is needed in these studies is not so much a vaster
number of families as more families that have been com-
pletely and accurately studied. Human pedigrees, like
breeding records, are full of imperfect statements. The
whole truth is to be gained only by visiting the families
and carefully cross questioning them.
VII. Conciustons
What conclusions can be drawn from a study of the
foregoing study of albinos?
1. Two albinic parents have only albinic offspring.
This holds for the families Nos. 1-3, comprising four
children altogether. These cases were all given us by Mr.
R. R., an intelligent and reliable albino. He married an
albino and had one son still, or until recently, living; al-
binic like his parents. These cases are, so far as I know,
the first that have been published.
Dr. R. A. Gortner tells us that he formerly knew
of a family of two albino parents and five albino chil-
dren near his home in Nebraska, but attempts to trace
this family have proved unsuccessful. The probability
that this rule will hold generally is enhanced from ex-
periments on animals where two albinos always yield
only albino offspring.
2. Even when neither parent of albinos is an albino
they are apt to be related. In 33 such families 11 are al-
most certainly from consanguineous matings. This is
33 per cent., a proportion that is certainly vastly greater
than that of the population at large.” The fact that
consanguinity even when present must frequently be
unknown heightens the probability that parents of al-
binos are usually related. The importance of this con-
clusion is that it tends to bring these cases under the
general rule that a recessive condition appears only
when both parents carry the same defect; and the prob-
ability that both carry the same defect is heightened
when both belong to the same strain.
* Lagleyze (1907) finds in 48 families of albinos consanguinity in 10, with
collateral antecedents in 7, non-consanguinity in 26, and unknown 5.
. 128 THE AMERICAN NATURALIST [Vou. XLIV
3. The proportion of albinos in any family probably
accords in the long run with Mendelian expectation, as
in other mammals. From two non-albinic parents the
proportion for families of four or more children is 34
per cent. albinos instead of the expected 25 per cent.
But various causes result in an omission of normal in-
dividuals and tend to swell the proportion of the abnor-
mal. When one parent is albinic and albino offspring
occur at all we get (Rip and 4 cases in P. W.), a total of
16 albinos and 15 pigmented, which accords with expec-
tation.
STATION FOR EXPERIMENTAL EVOLUTION,
OLD SPRING ARBOR,
eptember 8, 1910.
ie:
F. LITERATURE CITED
1867. Agassiz, L. and E. C. A Journey in Brazil. 540 Pp., Boston [The
edition cited is that of 1891].
1909. Bateson, W. In: Heredity and Disease. Proc. Royal Soc. of Medicine,
II [
1909. Davenport, G. C. and C. B. Heredity of Hair Color in Man. Ameri-
can Naturalist, XLIII, ‘obra April.
1896. Ehrmann, 8. Das pélznplische Pigment und die pigmentbildenen
Zellen des Menschen und der Wirbelthiere in ihrer Entwickelung
nebst Bemerkungen über Blutbildung und Haarwechsel. Bibliotheca
medica Abth D''!, Hft. 6, 80 pp., 12 Ta
1907. Lagleyze. Saal: des albinos. Arch, i ophikalmolagie, XXVII,
p. 280.
1909. Pearson, K. Note on the Skin Color of the Crosses between Negro
and Wh
ite. Biometrika, VI, 348-353, Pl. 1, March.
1909. Pearson, K. In: Heredity and Disease. Proc. Royal Soc. of Medicine,
II, pp. 54—60
1905. Young, H. B. Ilinois Medical Journal, XII, 201.
729
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SPAWN AND LARVA OF AMBYSTOMA JEFFER-
SONTANUM
PROFESSOR W. H. PIERSOL
UNIVERSITY OF TORONTO
SPAWN
Am{moxc the various accounts of the habits and spawn
of Ambystoma punctatum occasional mention may be
found of Ambystoma jeffersonianum but always in such
connections as to suggest that A. jeffersonianum is by
far the less common species in the locality. This along
with the considerable similarity existing between the
spawn of the two species may explain why no account
of the spawn of A. jeffersonianum has as yet appeared.
Descriptions of the spawn of A. tigrinum sufficient for
distinguishing it from that of the other two species is
given by B. G. Smith (1907).
In most localities near Toronto A. punctatum is a
much more common species than A. jeffersonianum,
however in one piece of woodland that is quite isolated
from all the others examined, the former species is
rarely to be found, while the latter is very abundant.
This woodland contains four pools that last throughout
the year, although they become heavily choked by vege-
tation during the late summer and autumn. The
value of these pools as a collecting ground for spawn,
Branchippus, etc., was discovered some years ago by
my colleague, Dr. Huntsman and his observations on
the Ambystoma spawn suggested to him the possibility
of distinguishing in it two kinds. Later the writer also
became familiar with this woodland in connection with
observations on Plethodon and with the consent of Dr.
Huntsman undertook also the investigation of the Amby-
stoma spawn of the pools.
The writer first visited these pools in spawning time
e EF
No. 528] SPAWN AND LARVA OF AMBYSTOMA 733
three years ago and found a small amount of spawn of
a type already familiar to him for some years from its
abundance in pools in other localities. But the greater
amount was of a type that. differed from this in the
points detailed below. These two types have proved to
be the punctatum type and the jeffersonianum type,
respectively. The predominance of the latter subse-
quently found its explanation in the fact that 31 of the
33 individuals captured in the woodland since then have
been of the latter species. It is impossible to determine
accurately the proportions in which the two types of
spawn occur, but estimating roughly, the jeffersonianum
type is at least ten times as abundant as the other.
As will appear below, a small percentage of the eggs
of A. punctatum will approach in size, or color, or mode
of deposition—but rarely in more than one of these
points at a time—the eggs of A. jeffersonianum. Con-
sequently, the separation of the latter as a type when
found in a pool where the punctatum spawn greatly
predominates, is not an obvious thing. But when the
proportions are reversed, as in the special pools men-
tioned, the distinction is most easily made. Observa-
tions in the field have agreed in all four seasons and
have been supplemented by the capture of females just
previous to egg-laying and comparison of mature ovar-
ian eggs and eggs laid by them in the laboratory, with
those obtained in the pools; and finally by the rearing
in the laboratory of larve from the two types of spawn.
The points of difference in order of constancy are as
follows:
1. Size-—The eggs of A. jeffersonianum are distinctly
the smaller, the usual diameter being 2—2.25 mm.
2. Color—The eggs of A. jeffersonianum are much
the darker, the pigment being but little removed from
a true black and covering a much larger proportion of
the surface of the egg than in A. punctatum; even the
lower surface is usually as dark as the upper surface of
many of the eggs of the latter species.
3. Time of Laying.—The deposition of most of the
734 THE AMERICAN NATURALIST [Vou. XLIV
spawn by A. jeffersonianum precedes that by A. puncta-
tum by a few days. It has been impossible to visit daily
the pools where the spawn of A. jeffersonianum is most
abundant, owing to their distance from the university;
one pool much nearer has yielded a small amount of it
and has provided more accurate although more scanty
data. In general the deposition of the bulk of the jef-
fersonianum spawn coincides with that of the first punc-
tatum spawn. Variations from this oceur—for instance,
this year the spawn in the single pool just mentioned
followed the above rule, while in the group of four pools
nearly all the jeffersonianum spawn had been deposited
three days before any punctatum spawn appeared; and
to complete the irregularity the last spawn of all to be
deposited was that of A. jeffersonianum. It was in
small quantity and probably all from one female.
(These eggs and the larve from them were unusually
small, the larve seemed vigorous, but could not be kept
alive many days after their own supply of yolk was ex-
hausted.) Another check on the time is furnished by
the spawning of Rana sylvatica. This year—an un-
usually early season—the writer observed the first
deposition of spawn in these pools by the wood-frog. It
began at 10.30 a.m., March 31. Spawn of A. jefferson-
ianum had appeared seven days previously.
4. Spawn-masses.—The typical spawn mass of A.
jeffersonianum is a small one, the number of eggs being
usually about twenty; the extremes encountered have
been small masses of jelly without any eggs and a mass
containing forty-one. A. punctatum does indeed deposit
masses of spawn containing as few eggs as this, but the
number is usually much larger. The complement of
ripe ovarian eggs carried by two females of average
size was 128 and 161. These are probably representa-
tive numbers and indicate a rather smaller complement
than that possessed by A. punctatum—130 to 225—
(Wright and Allen, 1908) which in turn is much smaller
P that of A. tigrinum—1,000 or more (Powers, 1907).
d. Hardly less characteristic than the small masses is
No. 528] SPAWN AND LARVA OF AMBYSTOMA 735
the manner in which they are frequently to be found at-
tached in succession to long slender twigs, each mass
being usually in contact with its neighbors. A sentence
in one paper on A. punctatum (Wright, 1908), ‘‘one
stem—had within a length of one and a half feet 14
bunches of eggs, 15-20 eggs to the bunch,’’ reads very
much like a description of spawn of A. jeffersonianum.
Many stems so laden have been found each year in the
special pools mentioned. The largest piece in Fig. 1 is
a portion of one of them. The twigs selected by A. jef-
fersonianum are, as a rule, very slender. A. punctatum
will make use of both stout and slender twigs indiffer-
ently, and no small quantity has been found attached to
the margins of leaves and to grass, even in the presence
of such twigs as are generally preferred. Eggs of A.
jeffersonianum have not been found except attached to
twigs or stems of water plants.
The low vitality of much of the spawn of A. jefferson-
ianum is a feature that has been noticed in each year.
No accurate estimate of the proportion that dies has
been made, but judged roughly by the conditions found
in the pools it is probably not overstating the loss to say
that three fourths of the eggs do not live to begin gastru-
lation. The same proportion of loss has occurred in
spawn reared in the laboratory, while spawn of A. punc-
tatum brought from the same pools a little later and
kept under the same conditions has suffered practically
no loss. The egg does not die, as a whole, but cells here
and there precede, the others going on dividing as usual
one-or more times, only to die at last. The surface view
of such an egg when death is complete shows an irregular
mingling of minute cells with many others two or three
times as great, and at intervals others even up to eight
or ten times as great, in diameter. These dead eggs
imbibe considerable water, and become very much larger
than the living ones and under natural conditions are
soon infected by fungi; but in the laboratory they have
been kept for weeks and have remained free from it;
showing that death has not been caused by a fungus that
736 THE AMERICAN NATURALIST [Vou. XLIV
only later becomes visible. All the eggs of a mass
either die or develop properly; one or two of the eggs
may prove exceptions to this, but whatever the defect
may be it involves practically all the eggs of a bunch.
Whether it may extend to all the eggs of a female it has
not been possible to determine. This loss has also been
observed in spawn of A. jeffersonianum from a second
locality and is not likely to be due to any quality of the
water, for in the pools of each locality spawn of A. punc-
tatum has been found developing with very little loss,
and that apparently due to infection by fungus. Neither
ean it be ascribed to low temperatures from early de-
position, for the earliest is no more liable to die than
that which comes later along with or after the spawn of
A. punctatum.
Larva
Spawn of A. jeffersonianum brought to the laboratory
has been allowed to develop and the larve fed until the
larger specimens had attained a length of 30-40 mm.
In these it has been possible to detect a peculiarity of
marking not present in similar larve of A. punctatum.
This peculiarity consists of a massing of dark chromato-
phores into three or four spots placed in a row along
each side of the mid-dorsal line, giving the animal, when
viewed from above, the appearance of being banded
(Fig. 2). Viewed from the side the same can be de-
tected, but is less conspicuous (Fig. 3). Incipient band-
ing is often indicated as soon as the chromatospheres
are well differentiated (Fig. 4). _
In looking over a large number of larve all gradations
will be found between individuals in which the above
shows distinctly and those in which it is impossible to
detect it. For example, in 115 laboratory-reared larve
examined at one time, 80 (69 per cent.) showed the dis-
tinctive marking. Of the balance, some individuals
under different conditions showed it also (either ex-
treme expansion or contraction of the chromatophores
obscures the pattern), but some never did. Exact num-
bers for this division of the 31 per cent. are not available.
Fic. 1. Spawn of A. jeffersonianum. Natural size. The eggs of some o:
the masses are bee others are in various stages from blastopore to fle ys
groove formatio
ay
j
bs aia rae”
Fig. 2. Larve of A. jeffersonianum. Enlarged thin ee Adutora. Gbromato-
phores considerably but not ae emely contracted.
Fic. 38. Larva of A. jeffersonianum. Enlarged ise diameters. ARE
phores considerably but not extremely expanded. The cera and right side ra
the trunk have pol dissected away and the ai a taken by both direct
and transmitted 1
refer enorme ome z Oee nn e
i i Rs
Fig. 4. Larva of A. jeffersonianum. Enlarged four diameters.
738 THE AMERICAN NATURALIST [Vou. XLIV
This year an attempt was made to remove all the
spawn of A. punctatum from the special pools. In the
middle of June larve 30-35 mm. long were collected
from them and examined as to this pattern; it was found
in but 35 per cent. Two causes may have contributed
to this—the abundance of brush in the pools may have
caused some spawn of A. punctatum to be overlooked,
and the great expansion of the chromatophores—much
greater than ever attained in the laboratory, the pools
being very dark, probably disguised it in some cases.
It was found impossible to put these larve under ob-
servation in the laboratory to test this point, for owing
to the long journey or to the change of water they in-
variably died within a few hours.
Little importance would have been attached to a point
of coloration so variable as this had it not been found to
be uniformly lacking in similar larve of A. punctatum,
whether raised in the laboratory or taken from the pools
known to contain little, if any, spawn of A. jefferson-
ianum. In view of the range of coloration for A. tigri-
num as larve (indicated by Powers), the degree of con-
stancy noted is perhaps the most that could be expected.
PAPERS CITED
Powers, J. H., 1907. Morphological Variation and its causes in Amblystoma
tigrinum. Univ. of Nebraska Studies, Vol. 7, No. 3.
Smith, Bertram G., 1907. The Breeding Habits of Amiina punctatum.
Amer. Nat., 41, pp. 381-390.
Wright, Albert i 1908. Notes on the Breeding Habits of Amblystoma
punctatum. Biol. Bull., Vol. 14, pp. 284-289.
Wright, Albert H., and Alien, Arthur H., 1909. The Early Breeding Habits
of PETTE TE punctatum. Amer. N at., Vol. 43, pp. 687—692.
THE INHERITANCE OF SIZES AND SHAPES IN
PLANTS
A PRELIMINARY Norte!
PROFESSOR R. A. EMERSON
UNIVERSITY OF NEBRASKA
Some years ago Lock reported a cross of a tall race of
maize with a shorter race which produced an intermedi-
ate height in F, and exhibited no segregation in F, when
crossed back with one of the parents.? Castle’s results
with rabbits are very similar to those of Lock with maize.
Castle summarizes his results in part as follows :°
A cross between rabbits differing in ear-length produces offspring
with ears of intermediate length, varying about the mean of the
parental ear-lengths. . A study of the offspring of the primary
cross-breds shows the blend of the parental characters to be permanent.
No reappearance of the grand parental ear-lengths occurs in generation
F,, nor are the individuals of that second generation as a rule more
variable than those of the first generation of eross-breds. . . . It seems
probable that skeletal dimensions, and so m5 A of skeletal parts,
behave in general as blending characters. The linear dimensions of the
skeletal parts of an individual approximate tas the mid-parental
dimensions.
From his own work with rabbits and Lock’s work with
maize, Castle offers this somewhat guarded generaliza-
tion :4
It is probable that in plants, as well as in animals, linear dimensions
are in general blending in their inheritance. . . . The obviously blend-
ing inheritance of height in this case [maize] does not contradict the
known Mendelian behavior of the growth habit in such plants as the
*This paper was presented, in substance, in a lecture before the section
of plant physiology of the Graduate School of Agriculture, Ames, Iowa,
July 8, 1910. The complete records are to be published later by the Ne-
braska ‘Agricultural Experiment Station.
* Lock, R. H., Ann. Roy. Bot. Gard. Paradeniya, 3 (1906), p. 130.
s Castle, W. E., et al., Carnegie Inst., Pub. No. 114 (1900), pp. 35, 43.
* Loc. cit., pp. 43, 44,
ee
740 THE AMERICAN NATURALIST [Vou. XLIV
sweet pea. .. . Dwarfness is plainly such a discontinuous variation in
plants as is hypophylangia in man, and its inheritance is quite different
from that of ordinary variations in height. The former is a discon-
tinuous variation, Mendelian in its inheritance; the latter belongs to a
series of continuous variations, and is blending in its inheritance.
While, in ease of most of the crosses that I have
studied where the parents differ in size, the F, indi-
viduals show an intermediate size, in no case have I ob-
served anything corresponding to Castle’s results with
rabbits or Lock’s results with corn. In every case with
which I am acquainted, there has been segregation of
size characters in F, following a ‘‘blend’’ in F,. The
cases in which this behavior has been studied most care-
fully are: size and shape of fruits of summer squashes
and gourds, varieties of Cucurbita pepo; size and shape
of bean seeds, Phaseolus vulgaris; size of grains and
height of stalks of Zea mays.
Size of Maize Grains.—Queen’s Golden pop corn, hav-
ing small grains, was crossed with Black Mexican sweet
corn, having grains of medium size. The grains of F,
plants are intermediate between the parents in size and
show no more variation in size than do the grains of the
parent plants.» F, grains, as regards size, while uni-
form for any one plant, show marked variation be-
tween different plants. The actual measurements can
not be reported at this time, but an examination of the
material on hand shows that there are some ears with
grains fully as large as those of Black Mexican, others
with grains quite as small as those of Queen’s Golden,
still others whose grains are about the size of the F,
5 On ears of F, plants of this cross there are of course about three smooth
starchy grains to one wrinkled, sugary grain. While, on account of ‘‘ double
PRAN > ?’ the endosperm, like the embryo, of F, plants i is to be regarded
as F,, exhibiting the ordinary F, oP eer the size of grains is a plant
character and to be regarded as F,. The wrinkled grains are apparently of
practically the same size as the smooth ones, though there is probably con-
siderable difference in weight between the two lots. In a study of weights,
use only the starchy grains of F, plants, and for the sugary parent only
starchy, ‘‘xenia,’’ grains produced through eross-pollination by the starchy
parent. It would doubtless be better, pS to avoid this difficulty by the
use of only starchy or only sugary parents.
No. 528] INHERITANCE IN PLANTS 741
grains, and finally grains intermediate in size between
F, and each of the parents. What will happen in F,
ean not be told until this season’s crop has been studied.
Height of Maize Stalks—Tom Thumb pop corn is the
smallest variety of maize that has come to my notice and
is fully as early as any I have seen. Plants, as grown at
Lincoln in 1909 and 1910, averaged about 90 cm. in
height, and had on the average about eight nodes. In
1909 they ripened in seventy days from planting. » This
dwarf early race was crossed with a late dent corn ob-
tained from Missouri. The stalks of the latter are above
medium height for dent varieties grown in this section,
though in the dry seasons of 1909 and 1910 they have
reached an average height of only about 225 cm. The
average number of nodes is about nineteen. The plants
failed to ripen fully in 1909, owing to late planting, but
were within perhaps a week of full maturity at the time
of the first frost, 120 days after planting. The F, plants,
as grown in both 1909 and 1910, are as uniform in height
as either parent, with an average height of about 182 em.
(about 25 em. above mid-parental height) and an aver-
age number of nodes of about 12 (14 nodes below the
mid-parent). In 1909 the F, plants ripened in about
100 days from planting (practically the mid-parental
season). The F, plants (about 250 are now growing)
range in size from that of the Tom Thumb parent to
above that of the F, plants. No plant, however, is so
tall as the large dent parent. While records have not
as yet been made of heights, number of nodes and earli-
ness in case of all plants, there is apparently little corre-
lation between height and earliness. Some of the
earliest plants are above medium height and some of
the latest are very short. As to correlation between
number of nodes and height and between number of
nodes and earliness, nothing can now be said.
Size and Shape of Summer Squashes.—A cross of
Yellow Crookneck and White Scallop has been grown,
and F, and F, studied in small numbers. The fruit of
742 THE AMERICAN NATURALIST [Vou. XLIV
Crookneck has a long neck with a bowl of only medium
diameter. Scallop has very flat fruits. F, is intermedi-
ate in both dimensions and therefore also in shape, i. e.,
in ratio of length to breadth. F, shows a complete
series of dimensions and of shapes from one parent to
the other. The mean dimensions and shapes and the
coefficients of variation in sizes and shapes for parents,
ı and F, are given in the following table.
Means. ‘ CoeMcisnits of Yanatia..
TO ene: Length, | Diameter, Shape, Length, | Diameter, Shape,
em. em, Te Di Per Cent. | Per Cent. | Per Cent.
Crookneck 39.6 11.4 3.47 17.0 12.0 13.8
Scallop 7.4 17.8 41 15.8 12.6 26.8
6
Mid-parent | 23.5 14.6 Batata CF 12.3 20.3
F, Hybrid 17.5 17.5 1.00 19.0 12.6 26.0
F, Hybrid 19.6 13.2 1.48 42.7 42.5 58.8
Size and Shape of Gourds.—A cross of Striped Spoon
gourd with Filipino Horned gourd has been studied.’
The Spoon gourd has a small, relatively long fruit. The
relation of length of the whole fruit to the diameter of |
the bowl is similar to Crookneck squash. The Horned
gourd has a short, relatively thick fruit. The ratio of
length to breadth is greater than in case of Scallop
squash. The following table gives the mean sizes and
shapes and coefficients of variation in size and shape of
the parents, F, and F,.
Means, Coefficients of Variation.
Ae or PPIE Length, | Diameter, PAN Length, | Diameter, Shape,
cm, cm. L: D. Per Cent. | Per Cent. | Per Cent.
Horned 10.3 9.0 1.14 9.4 9.9 10.9
Spoon 14.0 4.2 3.36. 15.6 16.0 11.8
Mid-parent | 12.2 6.6 a DF 12.9 11.4
F, Hybrid 12.9 5.6 2,27 15.8 15.7 13.4
F, Hybrid 15.7 5.5 2.87 37.5 21.2 40.7
° Mean of parent shapes.
"Shape of mid-parent.
*Most of the work with this cross is being done by F. W. armed
graduate student in plant breeding at the University of Nebraska.
° Mean of parent shapes.
* Shape of mid-parent.
No. 528] INHERITANCE IN PLANTS 743
Size, Shape and Weight of Bean Seeds.—Numerous
crosses of beans differing in size and shape of seeds
have been under observation. In only a few cases, how-
ever, have exact measurements been made. It will be
sufficient to report here combinations of three races:
Fillbasket Wax with large flat seeds; Longfellow with
long, slender seeds; and Snowflake Navy with small
round seeds. The mean dimensions, shapes and weights
and the coefficients of variation for parents, F, and F,,
are given in the tables below. The parent races and the
F, plants from which these records were taken were
grown in the garden at Lincoln in 1909. The F, plants
were grown in a greenhouse during the following winter.
The different generations are not, therefore, perfectly
comparable. In general the various races of beans and
F, plants that have been grown from time to time both
indoors and out have not been observed to exhibit
greater variations when grown in the greenhouse than
when grown in the garden, though the dimensions and
weights of seeds are often noticeably larger in case of
greenhouse-grown plants.
In case of the beans, summer squashes and gourds,
the mean dimensions and shapes of both F, and F, are,
with some exceptions, more or less like those of the mid-
MEANS
Race or Hybrid. TOS PN goa — DB: LTI BT
Longfellow 28.3 12.9 56 4.6 29 | 285| 12
Snowflake 16.4 8.3 5.7 4.7 1.5 1.8 13
Mid-parent 22.4 10.6 5.7 ar 1.9 2.3 12
F, Hybrid 18.4 10.1 5.7 4.3 1.8 2.4 1.3
Fillbasket $2.2 13.8 7.6 4.4 1.8 3.2 E7?
ngfell 28.3 12.9 5.6 4.6 23 2.8 LS
Mid-parent 30.3 13.4 6.6 4.5 2.1 3.0 1.5
F, Hybrid 28.4 13.0 6.5 4.7 2.0 2.8 1.4
F, Hybrid 36.8 14.1 7.0 5.0 2.0 2.9 1.4
Fillbasket 32.2 13.8 7.6 4.4 1.8 3.2 LJ
nowflake 16.4 8.3 5.7 4.7 1.5 1.8 1.2
Mid-parent 24.3 TLL 6.7 4.6 1.7 2.5 1.5
F, Hybrid 25.4 11.4 6.4 4.5 1.8 2.5 1.4
F, Hybrid 28.6 11.3 6.9 4.8 1.6 2.3 1.4
744 THE AMERICAN NATURALIST [Vou. XLIV
COEFFICIENTS OF VARIATION
. | Weight, | Length, | Breadth, | Thickness} L:B | L:T | B:T
Race or Hybrid. Per Cent. Per Rai. Per Cent. Per Cent. | Per Cent.) Per Cent.| Per Cent.
Longfellow 6.09 3.27 3.57 4.54 0.61 1.76 2.46
Snowflake 9.40 2.89 3.68 5.38 2.97 5.74 4.29
Snowflake 9.40 2.89 3.68 5.38 2.97 74 4.29
Mid-parent 8.67 3.06 2.94 4.58 3.18 5.87 4.07
F, Hybrid 3.47 2.70 3.83 1.2 7.06
9.90 ; i i 29 | 5.04
F, Hybrid | 24.48 | 8.32 | 5.96 8.05 | 7.26 | 39.74 | 9.01
parents. The most noticeable feature of the records,
however, is the coefficient of variation in F, as compared
with the parents and with F,. The coefficient of varia-
tion is not, on the whole, materially greater for F, than
for the parents. In F,, on the contrary, it is noticeably
greater than in F,. It is usually twice and in some cases
six or seven times as great as in F,. This is merely a
mathematical way of expressing the fact that the F, in-
dividuals exhibit marked segregation of size and shape
characters. If the intermediates seen in F, were tend-
ing to breed true as blends, the coefficients of variation
for F, would not be appreciably greater than for the
parents and for F,. This segregation in F, is so pro-
nounced as not to need statistical treatment for its
proper appreciation. Even a casual examination of the
material can not fail to impress one with the fact that
about all grades from one parent to the other are repre-
sented in F,. As a matter of fact, some individuals
among the F, gourds are decidedly larger than either
parent.
If such results as those reported here are to be ‘‘ex-
plained” by assuming that ‘variation is increased (in
some mysterious way?) by hybridization, we can doubt-
less also explain, in the same way, why this i increase in
No. 528] INHERITANCE IN PLANTS 745
variation is deferred until F, While predictions can
not be made with much assurance before F, has been
studied, it seems probable, nevertheless, as suggested
by East," that we shall eventually find that sizes and
shapes are not simple characters, but that a particular
mean size in reality depends upon two or more, perhaps
upon several, distinct factors, a part, or all, of which
exhibit incomplete dominance. If this were true, we
should expect intermediates (blends) in F, and a range
of variation from one parent to the other, or sometimes
even beyond the parents, in F, just as we do find in case
of many plant characters. It should also follow that
certain F, sizes breed true in F, while others continue
to break up, the variation in some cases extending over
the same range as in F, and in other cases over variously
restricted ranges. There is some evidence that this sug-
gentog behavior in F, occurs not only in regard to size
ters, but also in case of certain colors where
blends are seen in F,, but observations are as yet too
meager to be presented.
I am of course not unmindful of the many chances for
mistakes in interpretation of the facts secured in a study
of size and shape characters. In the apparently simple
cases of height of maize stalks or of bean plants, it must
be remembered that parents differing in height may also
differ in number of nodes, so that segregation in the
latter character might bring about differences in height.
. Number of nodes and average internode length must both
be studied instead of merely the product of these, actual
height. Or perhaps, parents can be found that differ in
height but have the same number of nodes. Confusion
resulting from increased fluctuations due to differences
in soil and season can be lessened by growing some
plants of all generations to be studied in the same sea-
son (from seed kept for the purpose or by repeated
crosses), and on as uniform soil as can be had. Even in
the same summer plants with different periods of de-
4 East, E. M., AMER. Nar., 44: 72, 73 (1910).
746 THE AMERICAN NATURALIST [Von. XLIV
velopment may be subjected to very different weather
conditions. This is of so much importance in maize, for
instance, that I am now beginning a study of size in-
heritance of crosses between parents arterie greatly
in size but only slightly in earliness.
There may possibly be definite correlations between
different dimensions, as length and breadth of the same
plant part. That is to say, shapes may be definitely in-
herited. Observations on F, bean seeds where the par-
ents differ in size but not in shape indicate that length
and breadth are probably not inherited independently
of each other. Large round beans crossed with small
round ones do not give any long slender beans in F, but
only large, medium and small, round ones. On the other
hand, when the parents differ in shape as well as in size,
intermediate and parental shapes as well as intermediate
and parental dimensions occur in F..
In short, the inheritance of sizes and shapes is not the
simple matter that the inheritance of, say, color is—and
recent developments indicate that color inheritance is
not always a simple three-to-one affair. It is certainly
well that most effort has first been directed to a solution
of some of the more simple problems of geneties. With-
out a knowledge of the later studies in color inheritance,
one could scarcely hope to get far in the investigation of
the inheritance of dimensions, weights and shapes, to
say nothing of such questions as whether ‘‘yield Men-
delizes,’’ which some are impatient to have answered at
once,
It has been the purpose of this paper to present a few
facts and to suggest many problems with the hope that
the attention of other students of genetics will be di-
rected to an interesting and important field not much
worked as yet.
SHORTER ARTICLES AND DISCUSSION
THE MODIFICATION OF MENDELIAN INHERITANCE
BY EXTERNAL CONDITIONS
A WHOLE number of the Biological Bulletin (May, 1910) is
devoted to Professor W. L. Tower’s article on ‘‘The Determina-
tion of Dominance and the Modification of Behavior in Alterna-
tive (Mendelian) Inheritance by Conditions Surrounding or
Incident upon the Germ Cells at Fertilization.’ The work was
done on certain chrysomelid beetles, Leptinotarsa signaticollis,
L. undecimlineata and L. diversa, all occurring in Mexico.
Every biologist who takes any interest in questions of heredity
will read this exceedingly important paper, and will be pro-
foundly impressed by the data therein presented, but it is pos-
sible that he will also be somewhat puzzled. It is in a humble
frame of mind that I venture to set forth some of the difficulties,
fully realizing that Professor Tower, with his long experience
in patiently investigating the chrysomelid beetles, must know
what he is about, and that any mere outsider is at a tremendous
disadvantage. At the same time, it is after all for the outsider
that the paper is written, and it is due to him to make it as clear
as possible, and it may be to explain what seem to him insuper-
able difficulties.
L. signaticollis 2 was crossed with diversa 3, giving in F,
about half signaticollis and half a blend between the two. The
F, signaticollis mated together gave only signaticollis, and
further breeding for five generations gave only the same.
blend, however, split in F, into signaticollis, the blend, and
diversa, giving the expected Mendelian ratios. (The obvious
suggestion here would be that the original male diversa was
heterozygous, gametically identical with the blend.)
Next, the same cross was again made, using beetles of the same
stock but at a reduced temperature. As a result, the F, beetles
were of one sort only, the blend; and these, when inbred, gave
in F, a typical Mendelian grouping. These two crosses were
repeated eleven times with substantially the same results.
It is to be noted here that signaticollis appears to be a form of
lower altitudes than diversa, and it seems possible that under
747
748 THE AMERICAN NATURALIST [Vou. XLIV
the reduced temperature the pure signaticollis perished, leaving
only the heterozygous individuals, giving the stated results.
Were this the case there would be no real modification of in-
heritance. So far good, but now we come to the next group of
experiments. Another cross was made, signaticollis 9 X diversa
g, under the same conditions as the first experiment, giving the
same results. Then the same beetles were used again, at re-
duced temperatures (as in the second experiment above), and
gave in F, only signaticollis, and this, inbred, continued true
for four generations. This experiment was repeated seven times
with uniform results. It seems astonishing that the cross in the
first set of experiments at a lower temperature should give only
the blend, and in the second only signaticollis. This, however,
is not only explicitly stated, but is illustrated by plates showing
the pedigrees of the beetles. In spite of all this there must be
something wrong, because on page 295 it is stated that the results
of the second group of experiments confirmed those of the first,
and on page 304 it is said that the results of the second were
“‘in every way the duplicate’’ of those of the first. On page 330
experiment H. 410 (the first group, at the lower temperature)
is said to have given beetles exactly like the female parent
(signaticollis), which subsequently bred true!
Is it possible that the description of H. 410 (p. 294) belonged
to something else and was accidentally put in the wrong place
when the paper was made up? If so, was the plate then made up
from the erroneous description? There is no reason, of course,
for doubting the accuracy of the experiments, but certainly there
is something wrong with the account of them.
On page 299, in experiment H. 701, there arose a ‘*single
pearly white larva [which] gave rise to a female exactly like the
parent type and four classes of larve.’’ Something has dropped
out here, and the statement as it stands is unintelligible.
In experiment H. 700 A (p. 296) a female undecimlineata
was crossed with a male signaticollis, giving only the female
(undecimlineata) type, which bred true for six generations.
“‘The male type was as completely eliminated as if it had never
existed.” This was not a result of parthenogenesis, as all efforts
to induce wndecimlineata to reproduce parthenogenetically failed.
Here it is interesting to note that undecimlineata differs prin-
cipally from signaticollis in having fully pigmented bands on
the elytra—a positive character. The larva of undecimlineata,
No. 528] SHORTER ARTICLES AND DISCUSSION 749
however, is white, while that of signaticollis is bright yellow—
the latter apparently the positive character. In the cross, the
larve and adults were equally of the wndecimlineata type, al-
though it was shown in another experiment that the larval and
adult characters were inherited independently, each of four
classes of larve giving rise to three classes of adults, with Men-
delian numbers. It was found perfectly possible for undecim-
lineata to have yellow larvee, and for signaticollis to have white
ones, when the right crosses had been made.
Are we to explain H. 700 A by saying that the result was a
genuine hybrid, from the make-up of which was somehow re-
jected the superficial characters of signaticollis?
Another class of experiments, described as ‘‘experiments in
synthesis’’ was productive of extremely interesting results. At
Cuernavaca, Mexico, a suitable spot was planted with the proper
food-plants, and stocked with 210 specimens of signaticollis,
‘‘from a standard location about a mile and a half distant’’ and
354 specimens of wndecimlineata. These freely bred together,
giving in the first generation 4,518 signaticollis, 11,744 mid-
type, and 5,091 wndecimlineata. Gradually, however, the sig-
naticollis increased at the expense of the others, until at length
it was the only form present. This looks like natural selection,
and it will be noted that it occurs in a region normally inhabited
by signaticollis. The experiment seems ideally perfect, except
for the stated circumstance that there was a‘standard locality
for signaticollis about a mile and a half away. From what we
know of the migrations of these beetles,t it does not seem un-
likely that the colony was overrun with immigrating signaticollis.
At Paraiso, in the foot hill rain forest, a locality was planted
with 100 each of signaticollis and wndecimlineata. This, I take
it, is in the wndecimlineata country. The result was exactly the
reverse of the experiment just described—or not exactly that,
for the signaticollis practically disappeared even in the first
filial generation. Many other particulars are given, and there
is an important theoretical discussion, but of course Professor
Tower has still in hand a great mass of unpublished material of
great value. One may hope that its appearance will not be too
long delayed.
T. D. A. COCKERELL.
1 For example, in six years I had never seen L. decemlineata (the potato
beetle) in Boulder, Colorado; but this year (1910) it appeared in enormous
numbers, flying. The tomato plants in my garden swarmed with them.
NOTES AND LITERATURE
NOTES ON HEREDITY AND EVOLUTION
MenpeL, in his investigations, found certain Hieracium hy-
brids which did not split up in the second generation. The
writer several years ago suggested that the cause of this phe-
nomenon might be found in apogamy. Ostenfeld* has recently
shown that in a large number of species of this genus apogamy
exists. It therefore seems probable that the constancy of these
hybrids is due to the omission of the reduction division.
Pearl and Surface? have recently published some very in-
teresting contributions on inheritance as a result of studies of
crosses made between Barred Plymouth Rock poultry and Corn- —
ish Indian Games. It was found that eggs produced by the
cross Barred Plymouth Rock males on Cornish Indian Game
females gave a larger per cent. of fertile eggs than the recipro-
cal cross; also a larger per cent. of fertile eggs than either pure
breed produced. The low percentage of fertile eggs in the cross
in which the Barred Plymouth Rock female was used, the au-
thors suggest, may possibly be due to unfavorable environment
for Cornish Indian Game spermatozoa in the Barred Plymouth
Rock oviduct.
There was also a higher per cent. of fertile eggs hatched for
the hybrids than for either pure breed, this result being attrib-
uted to the greater vigor of the hybrids.
The Barred Plymouth Rock ‘breed is one which has high egg-
laying quality, while the Cornish Indian Game has low egg-
laying quality. The very interesting result was obtained that
hybrids produced by using Barred Plymouth Rock sires were
good layers, thus showing that the high laying quality was
transmitted by the Barred Plymouth Rock sire. On the other
hand, hybrids produced by using Barred Plymouth Rock fe-
males did not possess the high laying quality, thus indicating
* Ostenfeld, C. H., ‘‘ Further Studies on Apogamy and Hybridization of
the Hieracium,’’ Zeitsch. f. Induk. Abst., Vol. III, H. 4.
*Raymond Pearl and Frank M. Surface, ‘‘Studies on Hybrid Poultry,’’
Annual Report, Maine State Experiment Station, 1910. See also Arch. f.
Entwick. d. Organ., XXX, p. 1.
750
No. 528] NOTES AND LITERATURE 751
that the Barred Plymouth Rock female does not transmit this
quality directly. The facts appear to indicate that high egg
laying quality is a sex limited factor like barring in the Barred
Plymouth Rocks. Barred Plymouth Rock females would thus
transmit high egg laying quality to their male offspring but not
to their female offspring, while Barred Plymouth Rock males
would transmit it to both sexes.
Shank color was also found to be a sex limited character.
Both breeds have yellow shanks, though the Barred Plymouth
Rocks sometimes have black pigment in the shank epidermis.
In the cross Barred Plymouth Rock male on Cornish Indian
Game female the progeny all have yellow shanks. In the re-
ciprocal cross the male progeny have yellow shanks, while the
female progeny have black shanks. The authors suggest that
shank color behaves like barring in transmission. There is,
however, evidently some difference, for here we get females
showing a character not possessed by either parent. The writer
would suggest, as a possible explanation of the behavior of
shank color, that the chromosome which determines the female
sex in the Barred Plymouth Rock probably has black shank
latent and that this character is aroused into activity by the
cross. The F, generation of this cross will probably give some
important information on this point. Fortunately, these care-
ful and indefatigable workers will continue these investigations.
In down color the hybrid chicks from the reciprocal crosses
were alike but unlike either parent, being darker than the dark-
est parent.
The F, generation between pea comb (Cornish Indian Game)
and single comb (Barred Plymouth Rock) gave all gradations
from pea to single. There were more pea combs in some fami-
lies than in others.
In body shape the males in the F, generation were all of the
Cornish Indian Game type. The females were intermediate be-
tween the two breeds in this respect. The barred females—that
is, those produced from Barred Plymouth Rock sires—were more
like the Barred Plymouth Rock in body shape, and the black
females more like the Cornish Indian Game.
In this paper the authors give the results of extended investi-
gations relating to inheritance of the Plymouth Rock Barring.
The paper is limited to the study of the cross between Barred
Plymouth Rocks and Cornish Indian Games. The results con-
752 THE AMERICAN NATURALIST [Von XLIV
firm the present writer’s hypothesis first published in 1908°
concerning the method of inheritance of this character. The re-
sults obtained are consistent with the hypothesis that barring is
allelomorphie to the female sex element. Thus, when male
Plymouth Rocks are used in the cross only the male offspring
are barred, the females being black. The plates accompanying
the text show excellent illustrations of the nature of the barring,
both in the pure bred Barred Rocks and in the hybrids. The
hybrids are darker than the pure breeds, there being more pig-
ment in the feathers.
Davenport has recently published an important contribution
in the Carnegie Institution series on inheritance in poultry.*
While he deals with many other characters than those relating
to color, for lack of time to present an adequate review of the
whole article, and because of its relation to the present subject,
I give here only his results relating to color factors. The factors `
determined were as follows:
C == presence of color (absence of C gives albinism) ;
J = Jungle Fowl pattern and coloration;
N = super Melanie factor (nigrum) ;
X == super Xanthic or buff factor;
W = Graying (white) factor.
He found the Silkies and White Cochins both to be pure
albinos having the gametic formula eJnwx.
White Leghorns were found to be grays with the formula
CJNWx. This formula shows that W is an inhibiting factor
which renders J and N invisible.
Black Minoreas and white-faced Black Spanish were found
to have the formula CJNwx. In these breeds N obscures J, but
the latter modifies the character black color.
Black Cochins were found to have the formula CINwx. In
this formula I is a modification of J in which the pigmentation
usually associated with J is absent.
Black Games were found to have the same formula as Black
Cochins, but the pigment due to the factor N is less intense.
Buff Cochins were found to have the formula CjnwX. The
author notes some variability in the degree of albinism, certain
recessive whites showing specks of pigment. ‘‘The coloring
enzyme may be absent to small traces.’’
* AMERICAN NATURALIST, Vol. 42, 1909, pp. 610-615.
* Davenport, C B, Brera of Character in Domestic Fowls,’’ Car-
negie Institution oablientiis
No. 528] NOTES AND LITERATURE 753
While the author recognizes sexual dimorphism as related to
Jungle Fowl pattern, he does not work out the manner of in-
heritance of this factor. He probably would have done so had
the birds been’ raised to the stage required for distinguishing
this dimorphism.
Breeders of White Leghorns are frequently troubled by the
appearance of a reddish sheen on the feathers. The formula of
this breed gives a probable reason for this difficulty (CJNWx).
It is probable that the Jungle Fowl coloration produces the ef-
feet in question. The cross between this breed and the Buff
Cochin (CjnwX) gives an opportunity to get a breed of the
formula CjnWx, which ought to be a pure dominant white, with
no trace of coloration or pigment.
Goodale® has recently published a short but very interesting
paper giving results of poultry breeding experiments, in which
it appears that the Jungle Fowl pattern found in the Brown
Leghorns, like the barring factor of the Barred Plymouth Rocks,
is allelomorphic to the female sex factor. His paper also shows
that while dominant white, when homozygote, is epistatic to
black pigment, it is not so in the heterozygote condition of the
white. It also indicates that females possessing the Jungle
Fowl pattern and having Plymouth Rock white and Plymouth
Rock black pigment, both in the heterozygote condition, may
vary in color from black to almost typical Brown Leghorn
pattern.
The progeny of females obtained by mating Brown Leghorn
females with white Plymouth Rock males show no trace of the
Jungle Fowl pattern or color, while the males obtained from this
cross transmitted the Jungle Fowl pattern. There is opportun-
ity here for a very interesting study. If the Jungle Fowl pat-
tern and the barring of the Plymouth Rocks are both allelomor-
phic to the female sex factor, it would be very interesting to
ascertain whether females can have both of these factors present
in them. If so, it would show either that the female sex factor
itself may be coupled with one or the other of these factors, or
that the allelomorph to this factor may contain both factors
coupled, or that the two factors reside in separate chromosomes
both of which behave as allelomorphs to the female sex chro-
mosome.
Castle has recently shown® that Miss MeCracken’s results in
° Proc. Soc. Exp. Biol. and Med., Vol. 7, No. 5, May 18, 1910.
° Castle, W. E., Jour. of Exp. Zool., Vol. 8, No. 2, March, 1910.
754 THE AMERICAN NATURALIST [Vou. XLIV
univoltinism and bivoltinism’ are not inconsistent with Men-
delian theory. The difficulty in interpretation is due to the
fact that the characters in question are exhibited by one sex
only. The same difficulty arises in following out the cross be-
tween white and red corn, since red shows only as an internal
character.
Hagedoorn,’ in mating an albino mouse having the barring
(agouti) character with a homozygous: yellow female, finds the
barring and the yellow color to be allelomorphic to each other.
Certain yellow individuals mated to black gave only yellow
offspring. It is probable that the yellow contains an inhibiting
factor for black. Other yellow mice of a different shade mated
to black gave black young. His results confirm those of Goodale
in that he finds the bankiva pattern and color in Bantams
crossed with Brown Reds to behave as if the bankiva pattern
were allelomorphic to femaleness. When females of the bankiva
type were used in the cross the male offspring were all bankiva
and the females all Brown Red. When the cross was made in
the opposite direction both sexes were of bankiva type. He
also found (page 26) some bankiva females apparently homozy-
gous for bankiva pattern. His data are not full or complete
on this point.
On page 29 he reports that the cross between Primula sinensis
and P. stellata gives P. pyramidalis. F, from this cross gives
25 per cent. sinensis, 25 per cent. stellata, and 50 per cent. Pyr-
amidalis, although the two parent forms differ in more than one
respect, the differences apparently being coupled.
The writer has frequently suggested that if a careful search
were made for more cases of what Bateson has termed ‘‘false
allelomorphs’’ they might be found to be more abundant than
they are thought to be. Those cases which have been dis-
covered show that such phenomena are not discovered usually
unless one is looking for them. We have now a considerable
number of cases of sexual dimorphism in which some somatic
character acts as an allelomorph to femaleness. Presumably,
these sex-limited characters would act as allelomorphs to each
other if brought together in the same zygote. We have already
referred to the barring of Plymouth Rocks and to the Jungle
* Jour. of Exp. Zool., Vol. 7, No. 4.
* Hagedoorn, A. L., ‘‘ Mendelian Inheritance,’’ Arch. f. Entw. d. Organ..
Vol. 28. H. 1.
No. 528] NOTES AND LITERATURE 755
Fowl pattern as instances of this kind. When Silkies are
crossed with Brown Leghorns, the latter breed introduces an
inhibiting factor for the intense black pigmentation in the
flesh of the Silkies, and this inhibiting factor appears to behave
as if it were allelomorphic to femaleness. The inheritance of
the factor is not yet fully worked out.® In addition to these
cases we have that of melanism in Abraxas grossulariata when
crossed with A. lacticolor. Black eyes in canaries when crossed
with pink eyes appear to behave in a similar manner. We have
already mentioned above shank color in poultry in this connec-
tion.
Dr. R. A. Gortner, of the Station for Experimental Evolution,
Cold Spring Harbor, New York, in THE AMERICAN NATURALIST
for August, 1910, gives results of quantitative determinations of
melanin in white wool and blaek. He finds 1.84 per cent. in
black wool and only .06 per cent. in white. He expresses the
opinion that the melanin in white is a decomposition product
of keratin and not a true melanin, thus disproving Riddle’s
assumption that dominant white is a more advanced stage of oxi-
dation than black. He advances the theory that dominant
whites are due to the presence of an anti-oxidase which prevents
pigment formation, while recessive whites have neither power to
` form pigments nor to inhibit the formation.
Ostenfeld’? finds that the number of chromosomes in the apo-
gamic race of Rosa canina is about double the number in the
normal sexual race in the same species, thus indicating that the
reduction division is omitte
It has generally been SER that when an organism is
moved from one environment to another distinctly different,
there is a tendency for the type to break up. This thing has
been described as ‘‘new place effect.’’ There has been very
little investigation bearing directly on this question, and most
of it has related to forms more or less mixed in inheritance
rather than to pure lines of the same inheritance. Data bearing
on this subject are important and very much needed. An impor-
tant contribution to our knowledge of the subject is found in
Bulletin 128 of the Bureau of Chemistry of the U. S. Depart-
ment of Agriculture. In this bulletin LeClere and Leavitt give
the results of experiments on wheat. Kubanka Wheat grown
°«*Bateson’s Mendelian Principles of Heredity,’’ pp. 81-87.
” Zeitsch. f. Induk. Abst. und Vererb., Bd. III, H. 4, May, 1910, p. 253.
756 THE AMERICAN NATURALIST [Vou XLIV
in South Dakota was distributed to stations in Kansas and Cal-
ifornia. Each year a sample from each station was sent to each
of the others and grown there. A similar series of experiments
was conducted with Crimean Wheat in Kansas, Texas and Cali-
fornia. The results may be briefly stated as follows.
The same variety of wheat when grown at the same station,
no matter what the source of the seed, showed the same charac-
teristics, but the same variety grown at different stations showed
marked differences. This result was obtained in the case of
both varieties. These results are in entire accord with the
results on barley secured by Dr. Albert Mann, who grew pedi-
gree seeds of barley at a large number of stations in this coun-
try. The original seed was from Svalöf. These results have
been previously referred to in these notes.
The appearance of an English edition of de Vries’s ‘‘The
Mutation Theory’? (Vol. I) gives the opportunity for many
non-German readers to gain first hand knowledge of this re-
markable work. It also serves to show the truly wonderful
progress that has been made in the study of the phenomena of
evolution since this book was originally published (1901-03).
In reading this book one can not fail to be impressed with
the current misconceptions concerning its teachings. De Vries’s
disciples have giyen the phrase ‘‘discontinuous variation” a’
meaning quite different from that in which it is used in ‘‘The
Mutation Theory.” By ‘‘continuous’’ variability de Vries means
the kind that fluctuates about a norm and thus presents a con-
tinuous series of modifications. Illustrations of continuous var-
iability in this sense are found in ordinary fluctuating variations
within pure lines. It was Quetelet who first discovered the fact
that ordinary fluctuating variability gives a continuous series
of variations varying in frequency inversely with their magni-
tude. That is, the magnitude of a given variation of this kind
is governed by the ordinary laws of probability. In such varia-
tion every degree of departure from the normal is found. On
the other hand, if we study a given character in a complex
Linnean species consisting of several pure strains or subspecies,
we find that each of the pure strains gives us a case of continu-
ous variation—i. e., of ‘‘fluctuation’’ about a norm which is
fixed. But if we take these norms for a large number of pure
“de Vries, Hugo, ‘‘The Mutation Theory,’’ Vol. I, Th
Peg E ; e Open Court
-Publishing Co., Chicago, I., pp. 575. °
No. 528] NOTES AND LITERATURE 160
strains within a species and attempt to arrange them in a fre-
quency polygon, we find gaps not represented in the series, at
least in some species. This kind of variation de Vries calls
‘‘discontinuous variation.’’ We can all agree that there are
such gaps between related forms in many cases. Thus, if we
adhere to the original use of the term ‘‘discontinuous varia-
tion,” there is no chance for debate about it. It is simply a
name given to a series of well ascertained facts. How these
gaps came into existence is another question. The change in the
use of the term which has occurred since ‘‘The Mutation
Theory’’ was written is in its application to the method by
which these gaps came to exist rather than to the fact of their
_ existence.
A careful consideration of the data now at hand seems to the
writer to leave little question that there are gaps between re-
lated forms which came into existence suddenly, and thus repre-
sent discontinuous variation in the more modern sense of this
term. The only dispute which seems to the writer justifiable
relates to the question whether all permanent evolutionary
change comes about in this manner; and this question will be
brought up again later in this article.
The progress made since ‘‘The Mutation Theory’’ was pub-
lished is illustrated by the fact that in this book de Vries takes
no account of the pure lines differing quantitatively with ref-
erence to a given character, such as those studied by Jennings,
Johannsen, Nilsson-Ehle and others. De Vries also adheres
throughout the book to the old notion that a given character can
be modified quantitatively by selection, and states on page 51
that ‘‘It is to the selection of the material afforded by individual
variability [fluctuation] that the origin-of many improved races
is due.” Many other similar statements occur in the text. Re-
cent investigations have thrown much doubt on the correctness
of this view; we may say, have disproved it. All the recent care-
ful work on the subject points to the opposite conclusion.
While in this book de Vries sets forth very clearly the idea
` that his “‘individual variation’’ is what we now call fluctuation,
he continually confuses fluctuation with the effect of crossing.
For instance, on page 100, we find the following: ‘‘ All this
[improvement of the sugar beet] has been done by selection of
the best individuals afforded by ordinary fluctuating variation.
Neither spontaneous variations nor crossings have played any
758 THE AMERICAN NATURALIST [Vou. XLIV
part in it. We are dealing here with the process in its simplest
form.” It is far from demonstrated that crossings have had
nothing to do with the improvement of the sugar beet. The
consensus of opinion of most biologists at the present time is
that selection can accomplish nothing except the isolation of
the best strain or best Mendelian combination existing in a given
population. It is hardly fair, however, to attribute to de Vries
the opinions expressed ten years ago, for he would probably
hold to-day that the opinions expressed concerning the effect of
selection in ‘‘The Mutation Theory’’ have been proved to be
incorrect. Such a position is really more in keeping with the
fundamental principles involved in his theory, and I have no
doubt that de Vries would fully admit that selection can not
affect fluetuating variability, or at least that all of the recent
evidence points in this direction.
For the purpose of discussing de Vries’s fundamental
theorem we may classify the various types of variation as fol-
lows: (1) Fluctuation; (2) those due to Mendelian recombi-
nations; (3) those due to change in personnel of the chromo-
_ somes or other cell organs having a relation to ontogenetic
development; (4) those due to fundamental changes in what-
ever material is responsible for the metabolic activities which
result in development.
Fortunately, at the time ‘‘The Mutation Theory’’ was written
the general facts of Mendelian recombination were recognized
and are taken into account by de Vries, though, as previously
stated, he frequently confuses them with other types of varia-
tion. De Vries also recognizes fluctuation, which he describes
by the term ‘‘individual variability,” and appraises it at its
true value, except, as stated above, that he credits selection with
the power of producing temporary modifications by means of it.
The last two types of variability were not recognized when
‘‘The Mutation Theory” was written, so that they are utterly
confused in this book.
Before de Vries undertook his Œnothera studies he was al-
ready committed to a theory concerning the manner in which
evolutionary changes come about, and frankly states that his
work was undertaken in order to find confirmation of this
theory. Strangely enough, Darwin was responsible for the
fundamental idea underlying de Vries’s theory of mutation.
It will be remembered that in attempting to explain the sup-
No. 528] NOTES AND LITERATURE 759
posed inheritance of acquired characters Darwin formulated the
theory of pangenesis, according to which each cell in the organ-
ism gives off a bud, or gemmule, which migrates to the germ
plasm and in the next generation becomes responsible for the
development of a corresponding cell in the new organism. De
Vries drops the idea of migration of the gemmules from the
organism into the germ plasm, and starts with these gemmules
as permanent constituents of the germ plasm. He also makes
other modifications in the nature of these bodies, and hence very
properly gives them a new name, ‘‘pangenes.’’
I am of opinion that had de Vries taken an agricultural va-
riety of wheat for his studies he would have been led to the
development of a different theory. Unfortunately, he found
the mutations for which he was looking in a species which was
throwing off variants in a manner which we may well believe to
be unusual. In fact, de Vries examined over a hundred spe-
cies before he found one that suited him in this respect. Re-
cent cytological investigations by Gates, Miss Lutz and others
seem to justify at least the tentative assumption that the Œno-
thera mutants arise from a change in the personnel of the chro-
mosomes. It is certain that in G@nothera gigas the Lamarckiana
the number of chromosomes has been doubled. Gates has shown
that in a general way the nuclei in gigas cells are twice the size
of those of Lamarckiana. Other mutants have numbers of chro-
mosomes not exactly corresponding with Lamarckiana. It is
also demonstrated that in Lamarckiana and several of its mu-
tants the course of events in the reduction division is abnormal.
A good many of the chromosomes do not unite into bivalents in
the usual manner, thus giving opportunity for all kinds of ir-
regularities in the distribution of the chromosomes. The fur-
ther fact that many of the mutants produce only a small pro-
portion of functional gametes at least suggests that in many
reduction divisions the chromosomes are distributed in such a
way as to interfere with the future development of the gametes
and the zygotes which would be formed from them.
If we assume that the chromosomes, because of their relation
to the processes of nutrition or for other reasons, have an im-
portant influence on the course of development, and that there
are irregularities in the distribution of these bodies in the re-
duction division in Lamarckiana and its offshoots, we at once
find a satisfactory interpretation of the behavior of these mu-
760 THE AMERICAN NATURALIST (Vor. XLIV
tants, and we can easily see how de Vries was misled by his ma-
terial. He got the idea that the organism is composed of dis-
tinct and independently heritable units and that when one of
these units is lost out or when a new one springs into existence
we get an organism which differs in all of its characters from
the parent form. He assumes that all permanent evolutionary
change comes about by the introduction of new pangenes. For
instance, he says:
The contrast between these two groups of phenomena, variability (in
the strict sense) [fluctuation] and mutability, becomes obvious when we
imagine that properties of organisms are built up of perfectly distinct
and independent units. The origin of a new unit is a mutation.
. Again on page 57:
Elementary species and forms closely allied to them are distinguished
from one another not by a single feature but by all their organs and
peculiarities. The difference between closely allied forms often de-
mands long and extensive diagnosis. Nevertheless this diagnosis must
be regarded as an expression of a single character, a single unit, which
arose as such, and as such ean be lost.
Again, on Page 61; ‘‘By mutation new characters arise all
at once’’; and on page 63: ‘‘Each mutation is a definitely cir-
eumscribed unit.’’
De Vries overlooks entirely those closely related pure ina,
differing frequently only quantitatively, and in a single char-
acter, which to the writer represent what may be called normal
evolutionary change. They not only do not differ in all their
characters as the Gnothera mutants do, but their norms pre-
sent a regular series coming under Quetelet’s law, and thus
represent ‘‘continuous variation,” as de Vries defines it. Yet
they are undoubtedly of true evolutionary value. Of these
types Jennings says :+7
The work with genotypes [pure lines] brings out as never before the
minuteness of the hereditary differences that separate the various lines.
These differences are the smallest that ean possibly be detected by re-
fined measurement taken in connection with statistical treatment.
And again on page 145:
That smaller hereditary differences are not described is certainly due
only to the impossibility of more aceurate measurements.
Genotypes
12 AMER. ee XLIV, pp. 144-145. ;
No. 528] NOTES AND LITERATURE 761
so differing have not risen from each other by large mutations. The
genotype work lends no support to the idea that evolution oceurs by
large steps, for it reveals a continuous series? of the minutest differ-
ences between great numbers of existing races.
Nilsson-Ehle, in dealing with genotypes of oats, shows that
the related lines can be arranged in a Quetelet curve with respect
to the average length of the flowering glume,™ as follows:
Average length of hull mm. Number of genotypes
14-15 2
15-16 16
16-17 38
17-18 14
18-19 2
It would be difficult to imagine a better case of ‘‘continuous
variation,’’ as defined by de Vries.
To the writer it seems there can be no doubt that the type
of variation illustrated by these pure lines of oats, and by the
many pure lines of Paramecium studied by Jennings, is alto-
gether different from that studied by de Vries, and is due to
a widely different cause. In the writer’s opinion, the nothera
mutants are due to irregularities in the distribution of chromo-
somes in the reduction division, while the hereditary variations
of the Paramecium type are due to actual changes in function
(inerease, decrease) of cell organs that have a relation to de-
velopment. When such changes occur in the functions of
chromosomes, the resulting differences obey Mendel’s law; when
they occur in other cell organs they do not obey this law.
De Vries simply generalized from too small a range of phe-
nomena. There can be very little doubt that had he worked
with the numerous small differences that exist in many species,
such as -have been the subject of later studies by others, he
would have come to a different conclusion, or would have at
least greatly modified his conclusions. The work with geno-
types certainly points to a different cause for evolutionary
change from that assigned by de Vries. Had he recognized
what we may call the Paramecium type of mutation he certainly
would not have said (p. 155):
The assumption that human variability bears any relation to the
variation that has or is supposed to have caused the origin of species
*Ttalies mine.
“ Bot. Not., 1907, pp. 113-140.
762 THE AMERICAN NATURALIST [Von. XLIV
is to my mind absolutely unjustified. . . . Since the beginning of the
diluvial period man has not given rise to any new races or types. He
is, in fact, immutable, albeit highly variable.
But even those of us who do not believe that all evolutionary
change is saltatory, as it seems to be in the Gnothera mutants,
can agree with de Vries that the difference between fluctuation
and mutation lies in the fact that fluctuation is due to environ-
ment and is not hereditary, while, when a step has actually
been accomplished in permanent evolutionary change, the norm
about which fluctuation occurs is different from the old one.
We can accept this doctrine even if we deny that the difference
between the new and the old is not a ‘‘unit.’’ We can not, how-
ever, accept the idea, repeatedly brought forward in this book,
that ‘‘There is no question that improvement takes place in the
experimental garden’’ (p. 110) when selecting for improvement
in pure lines, or when he says ‘‘In the case of no single char-
acter can selection be relaxed’’ (p. 106); or when he quotes
Halley (p. 111), with approval, to the effect that in improving
wheat by selection, ‘‘the rate of improvement gradually falls off
year by year until at the end of many years the race reaches
a maximum and becomes constant. But, of course, it will not
remain so if it is not subjected to continuous selection.’’
W. J. SPILLMAN.
(To be continued.)
INDEX
NAMES OF CONTRIBUTORS ARE PRINTED IN SMALL CAPITALS
Algae, Nuclear Phenomena of Sex-
ual saty yenien in the, BRADLEY
alamander, Roy
ALLEN, J. A., The Rabbits E ‘North
Amer ica 5 57; See
ton’s Life Palsy of "Northern
Animals, 12
Am mbystoma, aera es Spaw
and Lar f, W: H. PIER
Pierra Caas in the Evolu-
tion of Pinus, Irvine W. BAILEY,
284
Moore Davis, 513
Alimentary peal of a yrkena re
, 367
Anatomy, Comparative, of Conifers,
E. C. JEFFREY,
Angiosperms, Nuclear Phenomena of
Sexu a Repr esaer in D. M.
R, 604
Animal Be eenia and Habits, 572
neads, The Significance ‘of the
Courtship and Secondary Sexual
otrasmi of, THOS . MONT-
GOMERY, 1
phic Roinaney: A. E. ORT-
Arithmetic of the Product Moment
Method of Caleulating the Coeffi-
Sah vg Correlation, J. ARTHUR
HAR 693
Artificial "Production of the Parthe-
nogenetic and Sexual Phases of
the Life Cycle of Hyinns senta,
; NKLIN SHULL, 14
Artificially Produced piece Modi-
fications, The Appearance in the
Offspring of, FRANCIS B. SUMNER,
5
Bal Irvine W., Anatomical
Characters in the DORA of
Pinus, 284
Barnacie, Stomatolepas, Commen
n the
sal
Throat of the ha ge
Ti urtle, HENRY A. PILSBURY, 304
BARNES, CHARLES R., The Nature
of Physiological Response, 321
Bauer, E., Inheritance in Antir-
rhinum, 506
Beard, John, Sex in Animal Devel-
opment, 2
Beaufort Fishes, E. W. GUDGER, 395
er
RSOL, 739 j
í
|
|
|
Bee, tg pd e Sense of the,
JOH 73
Bi modal Variation Polygon in gis
Th its
des alictroides and
Aangan ea Sp R J.
AR R HARRIS, 19
Hanger: 308
Boring, Alice M., A Small Chromo-
e in Ascaris megalocephala,
24
Boulenger, G. A., Grayia,
Boveri, Th., Chromatin in Sex De-
termination, 246
BRAI EZRA The Evolution of
Nev ew gy through Hybridism,
22
BRAY, ee M L., Distribution ro
Movements P De sert Plants,
Brow wink: . N., The Effects of Ee
tirpation a and of Tra ansplantation
of the Reproductive Organs of
Insects, 316
Bubonic Plague, H. B. Warp, 439
areg S Larva and Spat of
. SAFFORD, 343
[Shem Nanak Salamander, The Ali-
Roy L.
Russo on Sex- deter-
tion in Gymnosperms,
Chance, The Logic of, in Problems
of Genetics, ARTHUR S. DEwING,
567
Chromosomes and Heredity, T. H.
MORGAN, 449
CLARK, AUSTIN H., Probable Origin
of the Crinoidal Nervous System,
243
COCKERELL, T. D. A., The Miocene
Trees of the Rocky “Mountains, 31;
Catalogue of Hemipterous Insects,
e-
lian a by External Con-
63
764 THE AMERICAN
ditions, 747; The Scales of Fishes,
185, 634 |
Coefficient of bg cr Arith- |
metic of the Product Moment |
Solent of Caleuating the, J. |
ART S,
Color, pinaingrn, in Teint dioca
hy GEO
the Honey Bee, JoHN LOVE , 68
mare ee The a en Anatomy
, E. ©. JEF , 253
Crinziaat Nervous System, iseer
Origin of, AUSTIN H. 243
Cryptograms, The Nomenclature of,
Species Plantarum of Lin s as
E for the Starting Point of
W. G. FARLOW, 385
DAHLGREN, ULRIC, The Origin of the
Electricity Tissues in Fishes, 193
Phe ra
N,
S and Darwin-
me, V L. E, 382
., The Imperfection
Dominance "and Some it
nsequences, 129
Davenport on the Ophidian Genus
, COCKERELL, 703
par etn C. and
B., redity of Skin
Pigmentation in er n, 641, 70
a
oF
=
D
la}
=
=,
og
=
a
m
etr
me
o so S
Fh a
a
o
Z
E T o E
Davis, BRADLE , Genetieal Stu-
dies in Oen oth era, 108; Nuclear
henomena of Sexyal Reprodue-
tion in the Algae, 513
DEAN, Bas porn An Deen
entury Microscope, 302
rt Plants, Distribution and
Movements of, WILLIAM L. Bray,
443
deVriesian Theory, Mendelian Phe-
nomena without, W. J. SPILLMAN,
214
DEWING, ARTHUR S., The of
Chanee in sacl ja of aes ha
567
Dindes Sauropod, gi of
the Wackevatinas of, J: Hou
LAND, 259; Saropvious, The Pias
of the, 7
Doflein, Lehrbuch ie Protozoen-
kunde, mice A. Korom, 379;
and Hes the Structure hee
Habits oe Prien G. H. PAR
The Imperfection of,
and pom of its Consequences, C.
B. DAVENPORT, 129
NATURALIST [VoL. XLIV
East, Epwarp M., A Mendelian In-
£ Varintion that is
: Ei Ti-
heritance in Po jae
ee L., Vorl wie sn über den
r nervösen Centralorgane,
G. H. PARKER, 63
EIGENMAN, m
brates of Atari I
Electricity Tissues in Fishes, The
H., Cave Verte-
Origin of, ULRIC DAHLGREN, 193
EMERSON, R. A., heritance of
Sizes and Shapes in Plants, 7
bridism, EZR 9;
of Pinus, Anatomical Chavaster 3 in
the Evolution of,
BAILEY, 284; without onary
Jo . GULICK, 561; Elem
ieee ee
tary, V.
xperiment tal pain on the ——
tiveness of Selection, H. S. JEN
NINGS
Fartow, G. W., Species Arien
of. Lidimics as a Basis for the
Starting Point of the in
ture of Cryptograms, 385
ayûm Mammals, Schlosser on the,
TTHEW, 700
, E. W. GUDGER, 395
, Are they Inherited?
, 412
Phenomena of Sex-
ual Reproduction in, R. A. Har-
, 533
Gates, REGINALD R., The Material
Basis of Mendelian Phenomena,
203
ag oie Studies A Oenothera,
BRA’ Te Davis, 108
daian, e Logie of Chance Te
Problems of, ARTHUR S. DEWI
GORTNER, Ross AIKEN, ‘Spiegler’s
White Melanin as related to Dom-
inant or Recessive White, 497
UDGER. E. W., Notes on Some
Beaufort Fishes, 395
Jo OHN E., Evolution without
561
. The Chromosome
eory of Heredity, 510
Gymnosperms, Nuclear Phenomena
of Sexual Reproduction in,
CHARLES J. CHAMBERLAIN, 595
HARGITT, CHARLES W., The Spawn-
No. 528]
ing yeaa of Hydroides Dian-
thus wee
Harp er > R. A., Nuclear Phenomena
of a apne in Fungi,
aot J. ARTHUR, A modal
o h oduct
d of Calculating the Co ofi.
cient of Correlation, 693
Ichthyology, N a on, DAVID STARR
JORDAN, 179, 634
Inheritance, Color, in gfe dioca
» GEORGE HARRISON SHUL
, R.A. E
delian, Modification by External
Conditions, T. D. A. COCKERELL,
Pointin. Evolution without, John
T. Gulick, 561
Heredity, and Chromosomes, T. H.
RGAN, 449; W. J. SPILLMAN,
504, 750; of Skin Pigmentation in
Man, Gr ERTRU Cc AVENPORT
and CHARLES B. DAVENPORT, 641,
7
HERRICK, FRANCIS
D the Str
ture and Habits of Animals,
H: Pie 572
HOLLAND, W. J., Criticisms of the
Restoration of Sauropod Dino-
sau
oney ’ Bee,
uc-
G.
Color Sense of the,
HN LOVELL, 673
Hunter, S. i The Green Bug and
its Enem ‘4
Hussakof, Li. ” Goblin Sharks, 182
Hybridism, The Evolution of New
F through, Ezra BRAINERD,
Hydatina senta, The Artificial pro-
duetion of P rt
The niae
S W. HARGITT,
Exper oe Evi-
dence on the PEETERS of Se-
=]
INDEX.
765
lection, 136
JORDAN, DAVID STARR, Note on Ich-
thyology, 179, 634
JORDAN, E., Te e of Sex
Determination,
K, L., Darwin’s Greatness and
Darwin’ s Weakness, 382
Kastle, 2 K., The Oxidases, 510
Kauffm aE = the
Saprolegniace, C. L. SHEAR, 573
Kirkald G A a iames of
PATA ea Insects, E Do,
COCKERELL, 191
Kororp, CH
RLES A., Doflein’s Lehr-
buch der Fa anaa, 379
Larva, and Spat of me Canadian
Oyster, J. SAFFORD, 343; an
Spawn of Ea jeffersoni-
W. IERSOL, 732
ersa North American, Nelson ’s
Monograph of the, J. A. ALLEN,
Leriche, meg Fossil Sharks of
Califor 181
‘Eble Si. ’? Facts about the,
Francis H. HERRICK
Love, Harry H., Are "Floctuationa
inherited @ 412.
> casi Sense of the
— dioca T Color Inheritance
n, GEORGE HARRISÒN SHULL, 8
McCLENDON, J. E The Effect of
xternal Conditions on the Repro-
‘duction of Daphnia, 404
Mammalogy, 57
Mammals, Colorado, T. D. A. Coc
ERELL, :
the, W. D
MARSHALL, F. R., The je ie Speed
Sires, 431
MATTHEW, W. D., The Pose of the
Sauropodo ous Dinosaurs, 547;
Schlosser -on the Fayûm Mam.
mals, 7
Meisenheimer, Johannes, The Effects
f
, 316
Melanin, Spiegler ‘White. ja ‘related
to Dominant or Recessive White,
Ross AIKEN GoRTNER , 497
Mendelian, Interpretation of Varia-
tion is apparently contin-
uous, rele M. East iew
of Melan nin Formatio
SPILLMAN, 116; P “The
T, ;
766
Material Basis of, REGINALD R.
GATES, 203; Inheritane ~ Mo difi-
cation 'by External Conditi ions, T.
D. A. Co
FORD DEA
Miocene Trees of the amn Moun-
tains, T. D: A. , 31
Modifications, Artificially setae
P-
ee, pen Bighteenth Century,
, 302
rental Modifications, The A
pearance in the oe of,
Francis B. la
MONTGOMERY, THos. H., Jr., The
Significance of the Courtship and
Secondary Character of
Araneads, 151
Moonie, Roy L., The Alimentary
Canal of a Cnibaniforous Sala-
mois
x Det termination
ids,
Repetition the t
pat = and Pipeeaatte Proces-
ses? 92
Pee MAX, Sterility, 624
Mortirr, D. M., Nuclear Phenom
of Sexual Reproduction i in ai
sperm
Nelson, E. W., The Rabbits of
North America, J. A. ALLEN, 57
Nervösen Centralorgana, Edinger’ s
co über den Bau der,
G. RKER,
63
N ervous aaea Kasara
Prob-
sey Origin of, AUSTIN H. CLARK,
243
Neurology, 63
NEWCOMBE, FREDERICK C., Plant
esponses in the Categories of
nsitive Reaction, 333
Starting Point of, W. G
38:
Notes and Literature, 57, 124, 178,
245, 308, 379, 434, 504, 572, 634,
700
Nuclear, Phenomena of Sexual Re-
produetio on in the A Alge, BRADLEY
miese Davis, oe in the Fungi,
E. A. HARPER ; Phenomena
= Sexual eae i in iht
S, CHARLES J. CHAM
yy 595; in aaia. D. M.
MOTTIER, 6
Nussbaum, M., Sex Determination
in Polyps, 251
THE AMERICAN NATURALIST
[Vor. XLIV
@Œnothera,
RADLEY
ee and Phylogenetic Proc-
WoE
Poes Seen in,
, 92
OrTMANN, A. E., Te ny ba ais
lenis, 237
Oyster, Canadian, Larva and Spat
of the, J. SAFFORD, 343
Parental Modifications, Artificially
produced, the Appearance in the
Offsprin ing of, FRANCIS B. SUMNER,
G. H., Edinger’s Vor-
‘lancape über "den
nd Habits of Animals, 572
Parthenogenetic, Eggs of Hymen-
optera, he
f Hydatina senta, Arti-
ficial Production of, A. Fran NK-
LIN SHULL, 14
Pearl, Lobster, Facts about the,
FRANC Cae ERRICK, 294
PEARL, seer ND, Quantitative Stu-
dies of Variation in Social In-
sects,
N, KARL, A Pickwickian Con-
tribution to Our Knowledge of
Wasps, 503
OL, W. hae Spawn and Larva of
Ambystoma jeffersonianum, 732
Pironi pee _Ontogenetie Proc-
a Ts gets a Repeti-
at Soe ULIS, 92
Physiologie Response, The Nature
HARLES R. BARNES, 321
Pian eS. Plant, 573
Pigmentation, an eA in
an, GERTR ú ENPORT
and eri B. Ve 641,
705
PILSBRY, HENRY A., Stomatolepas,
acle Comme nsal in the
Throat of the Loggerhead Turtle,
304
Pinus, Anatomical Characters in the
Evolution of, Irving W. BAILEY
Plant, pn bg e in the vise aas
of Sensi ea Reactions,
ae NEWCOMBE, 333; Parion,
io
No. 528]
aired ers one sow and
Shap , R. A. Em , 739
Pose of "the OAA Dio
. D. MATTHEW, 547
Potatoes, Inheritance in, EDWARD M.
EAST
Protozoa, 379
Rabbits of North America, J. A.
Allen, 57
REDFIELD, Sea PER L., The Age of
Speed Sires, 306; Retroactive
DA iri 564
TOER C. Tate , Eels from the South
as and Australia, 635; Classifi-
ceerd of the Teleostan Fishes,
636
Regeneration, is it a Repetition of
Ontogenetie and
; Sexual, in
ae $ i Angio-
M. , 604
Bobrodustive cheat of I Insects, ae
fects A T eg and - Tra
planta of, E. N. B NE, 316
pa Physiologie, The Nature
of, CH s R. BARNES, 321
Responses, P Plant, in tho "Ctepories
sierra aay cake FREDERICK
COMB 3
ETNE dili of g Seane Dinosaurs,
Criticisms of the, W. J. HOLLAND,
Retroactive Selection, CASPER L.
REDFIELD, 564
Riddle, Oscar, Aega „Color For-
ion and its ing on the
ma
Mendelian Dracripioa of Hered-
ity, 116
Rocky Mountains, Miocene Trees of
the, T. D. A. Co
KERELL, 31
Russo, pa Sex Determination and
i Modification of the
Mendelian Ratios, W. E. CASTLE,
434; H. E. Jordan, 246
SAFFORD, J., The Larva go Spat of
the Canadian Oyster
Salamander, pallet Bi T Ali-
mentary Canal of a, Roy
Moonie, 367
INDEX.
767
Sauropod Dinosaurs, Criticisms or
the — of, W. J. Hou
LAND
Saa ye Dinosaurs, The Pose of
t . MATTHEW, 547
e,
Schlosser m the Fayûm Mammals,
W. D TTHEWS, 700
Baker The Effectiveness of, Ex-
peri tal Evidence
atti 136; aen Cas-
REDFIELD, 564
PNT Reactions, Plant oat
n the Sar ries of, FREDERICK
C. NEwcom 3
Seton, Ernest Tien. Life His-
tories of Northern rnin an
Account of the onm als of Mani-
toba, J. A. ALLEN, 124
Sex Determination, “The Question of,
H. E. AN, 245; W. E. CASTLE
434
Sexual Characters and Courtship of
Araneads, The Significance of,
THOS- H. ear ony Jr., 151
SHEar, C. L., Ka n’s ny si-
ology of the A, 573
Shorter Articles and Discussion, 116,
302, 376, 431, 503, 561, 624,
SHULL, A. FRANKLIN, Do Partheno-
G E Harrison, Color In-
heritanee in a dioca, 1, 83
Sires, et the Age of, Cas SPER Li
REDFIELD, 306; F. R. MARSHALL,
Sizes and Shapes in Plants, In-
heritance of, R. A. EMERSON, 739
pe isomesog in Man, Heredity
ie
Social capi er aan in, Ray-
Sollas, Pr B. Ea Color Inheritance,
SPALDING, VOLNEY M., Distribution
and Movements of Desert Plants,
WILLIAM L. :
Spawn and Larva of Ambystoma
effersonianum, W. H. OL,
732
a fet oni of Hydroides Di-
nthus, CHARLES W.
iesiae Pan arum, as a Basis
the Starting Point of the Nomen-
T68
pha of Cryptograms, W. G.
FarLow, 385
Speed Sires The Age of, CASPER L.
306; F. R. ’ MARSHALL,
Spiegler’s White Melanin as re-
of Melanin Formation, set Peg
delian Phenomena wit
Eger Theory, S14. erodi.
Bor i Max Morse, 624
i A Barnacte commen-
head Turtle, Henry A. PILSBRY,
304
SUMNER, FRANCIS B., The Reap-
pearance in the Offspring of Arti-
ficially produced Parental Modi-
fication
Sy ndesmon Pewee oe Bimodal
Variation Polygon in, and its
Merghitdgičat Binila J.
ARTHUR HARRIS, 19
Tertiary Archhelenis, A. E. ORT-
isas, abaci, in Fishes, Ane
REN,
sects, Effect of, E. N. BROWNE,
31
Trees, Miocene, of the Rocky Moun-
ains, T. D. A. CocKERELL, 31
THE AMERICAN NATURALIST
[Vou. XLIV
Urosalpinx, Variation in, HERBERT
EUGENE WALTER, 577
Variation, Se -Pi modal, in
Syndesmon thalie raed and its
Morphological Significan e, J. AR-
THUR Harris, 19; A Mendelian
Interpretation of Varia
is apparently continuous, EDWARD
Bior T, 65; in Social Insects,
Quantitative Studies of, RAYMOND
EAR 08; in Urosalpinx, HER-
BERT EUGENE WALTER, 577
WALD L. R., A Suggestion. re-
garding Heavy and Light Wheat,
hen HERBE ERT EUGENE, Varia-
(T
Warren, E. R., Co aiig Mammals,
ea 9 CKERELL, 640
Wasps, A Piekwickinin Contribution
to Our Knowledge of,
PEARSON, 503
Webster, F. M., Toxoptera grami-
num and its Parasites, 127
Wheat, Heavy and Light, A Sug-
gestion regarding, L. R. WALDRON,
31
Wheeler, W. M., The Structure, De-
velopment a on of Ants,
G.
Wheldale, ‘Miss, itor Inheritance,
504
Wilson, E. B., Chromosomes, 246
Zoology, Experimental, 316
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The American Naturalist
A Monthly pera established in 1867, Devoted to the Advancement of the Biological Sciences
Factors ity
Special Reference to the
of Organic Evolution and Here
CONTENTS OF THE JUNE NUMBER
The Botanical Society of America :
para iy on of Ae for nae “Response, The Late Pro-
of Plant Responses in the Categories of Soran
tive Reactions. Professor FREDERICK C. NEWCO:
The Larva and Spat of the Canadian Oyster. Dr, J. a
FORD.
The eg mart Meta of a Carboniferous Salamander.
L. MOODIE.
ze Articles and Discussion: Observations on the
—- Ha vane of Tiyaroides Dianthus, Professor
—_— abet
olomu- Daela? s Lehrbuch der Protozoenkunde :
Piese aans
iw A. Kororp. Celebrating Dar-
win’s Seataue and Darwinism’s Weakness, SLK.
CONTENTS OF THE JULY NUMBER
A Se of the ‘‘Species Plantarum’’of Linnaeus
sa see for the ee g Point of e Nomenclature
ams, Professo
Notes on i ame Beaufort Fishes. E W. aren cutee
On ap A fae oe Sys 2 e ; E
Dr. J. F.
Are Fluctuations Inherited? Dr. p E:
Inheritance in Potatoes. Professor p ES Me Faer.
Shorter F and Correspondence: The Age of Speed
Sires: Professor F, R. MARSHALL.
Notes and Literature: Russo on Sex- Datenctagtion and
Artifical Modification of the Mendelian Ratios, Pro-
ae W. E. CASTLE ; The Bubonic Plague, Professor
. B. WARD; Desert Plants, WILLIAM L. BRAY.
CONTENTS OF THE AUGUST NUMBER
Chromosomes and Heredity. Professor T. H. MORGAN.
Spiegler’s “White Melanin” as Related to Dominant or
Recessi te. Dr. Ross AIKEN GORTNER.
Shorter Articles and Correspondence: A Pickwickian
Contribution to Our Knowledge of Wasps: Professor
KARL PEARSON.
Notes and Literature: Heredity, Dr. W. J. SPILLMAN.
CONTENTS OF THE SEPTEMBER NUMBER
Nuclear oan = Sexual T in the
Alge. DR. BRADLEY MOORE Davi
Nuclear Phenomena of aaa =e in Fungi,
PROFESSOR R. A. HARPER.
The Pose of the Sauropodous Dinosaurs. Der. W. D,
MATTHEW.
Shorter Articles and Discussion : Evolution without Iso-
lation, DR. JOHN T. GULICK. Retroactive Selection,
Cas FIELD. Th ic of Chance in
Notes and Literature: Animal Structure and Habits,
Professor G. H. PaRKER. Plant Physiology, C. L.
SHEAR.
CONTENTS OF THE OCTOBER NUMBER
Variations in Urosalpinx. Dr. HERBERT EUGENE
WALTER.
Nuclear Phenomena of Sexual sat esan in Gym-
nosperms. CHARLES J, CHAMBRE:
Nuclear Phenomena of Sexual Repro in Angio-
sperms. Professor D. M. Morrr
Shorter Articles and Discussion : am Dr. Max
MORSE.
Notes and Literature: sty on Ichthyology, ae
Davip eraen Jorp The oo olorado,
. D. A. Cobicentes
CONTENTS OF THE NOVEMBER NUMBER
Heredity of Skin paea in Man. ben C.
DAVENPORT and CHARLES B, DAVEN
The Color Sense of the Honey Bee—Can a cou
Colors? JoHN ne
Shorter Articles and ssion : The Arithmetic of the
Product Moment Method of ea neg the Coeffi-
cient of Correlation: Dr. J. A ABRIS.
Notes and Literature: Schlosser on Wate mals,
Dr. W. D. Marruew, The Ophidian rob Garik
Professor T. D, A. COCKERELL.
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