Talk:Heredity and Sex (1913) 8
CHAPTER VIII Special Cases of Sex-Inheritance
The mechanism of sex-determination that we have examined gives equal numbers of males and females. But there are known certain special cases where equality does not hold. I have selected six such cases for discussion. Each of these illustrates how the mechanism of sex-determination has changed to give a different result ; or how, the mechanism remaining the same, some outside condition has come in that affects the sex ratio.
It is so important at the outset to clearly recognize the distinction between sex-determination and sex ratio, that I shall take this opportunity to try to make clear the meaning of this distinction. The failure to recognize the distinction has been an unfailing source of misunderstanding in the literature of sex.
(1) A hive of bees consists of a queen, thousands of workers, and at certain seasons a few hundred drones or males. The workers are potentially females, and these with the queen give an enormous preponderance of females. In this case the explanation of the sex ratio is clear. Most of the eggs laid by the queen are fertihzed, and in the bee all fertilized eggs become females, because as we have seen there is only one class of spermatozoa produced, and not two as in other insects.
There is a parallel and interesting case in one of the wasps described by Fabre. The female lays her eggs
SPECIAL CASES OF SEX-INHERITANCE 221
as a rule in the hollow stems of plants, each egg in a separate compartment. In some of the compartments she stores away much more food than in others. From these compartments large females hatch. From compartments where less food is stored the smaller males are produced. It may seem that the amount of food stored up determines the sex of the bee. To test this Fabre took out the excess of food from the large compartments. The wasp that emerged, although small for want of food, was in every case a female. Fabre enlarged the smaller compartments and added food. The wasp that came out was a male, larger than the normal male.
It is evident that food does not determine the sex, but the mother wasp must fertilize the eggs that she lays in chambers where she has stored up more food, and not fertilize those eggs that she deposits in compartments where she has accumulated less food.
(2) A curious sex ratio appeared in one race of fruit flies. Some of the females persisted in producing twice as many females as males. This was first discovered by Miss Rawls. In order to study what was taking place, I bred one of these females that had red eyes to a white-eyed male of another stock. All the offspring had red eyes, as was to be expected. I then bred these daughters individually to white-eyed males again (Fig. 106). Half of the daughters gave a normal ratio ; the other half gave the following ratio :
HEREDITY AND SEX
It is evident that one class of males has failed to appear — the red males. If we trace their history through these two generations, we find that the single sex chro
Fig. 106. — Diagram to show the heredity of the lethal factor (carried by black X). A, red-eyed female, carrying the factor in one X, is bred to normal white-eyed male. B, her red-eyed daughter, is bred again to a normal white-eyed male, giving theoreticallj^ the four classes shown in C, but one of the classes fails to appear, viz. the red-eyed male (colored black in the diagram). The analysis (to right) shows that this male has the fatal X. One of his sisters has it also, but is saved by the other X. She is the red-eyed female. If she is bred to a white-eyed male, she gives the results shown in D, in which one class of males is again absent, viz. the red-eyed male. In this diagram the black X represents red eyes and lethal (as though completely linked).
SPECIAL CASES OF SEX-INHERITANCE 223
mosome that each red male contains is one of the two chromosomes present in the original red-eyed grandmother. If this chromosome contains a factor which if present causes the death of the male that contains it, and this factor is closely linked to the red factor, the results are explained. All the females escape the fatality, because all females contain two sex chromosomes. If a female should contain the fatal factor, her life is saved by the other, normal, sex chromosome. The hypothesis has been tested in numerous ways and has been verified. We keep this stock going by mating the red females to white males. This gives continually the 2 : 1 ratio. The white sisters, on the other hand, are normal and give normal sex ratios.
(3) Another aberrant result, discovered by Mr. Bridges, is shown by a different race of these same fruit flies. It will be recalled that when an ordinary whiteeyed female is bred to a red-eyed male all the sons have white eyes. But in the race in question a different result follows, as shown by the diagram. From 90 to 95 per cent of the offspring are regular, but 5 per cent of the females and 5 per cent of the males are unconformable, yet persistently appear in this stock.
The results can be explained if we suppose that the two sex chromosomes in the egg sometimes stick together (Fig. 107). They will then either pass out into one of the polar bodies, in whii^h case the red-eyed males will develop if the egg is fertilized by a female-producing sperm; or the two sex chromosomes will both stay in the egg, and give a kind of female with three sex chromosomes.
Here also numerous tests can be made. They verify
HEREDITY AND SEX
the expectation. Thus by utiUzing sex chromosomes that carry other sex-Hnked characters than white eyes, it can be shown that the results are really due to the whole sex chromosome being involved, and not to parts of it. The result is of unusual interest in another direction ; for it shows that the female-producing
W W/ V
Kr'< 9 > 95
(Qj ""^-9} -^
Fig. 107. — Non-disjunction of the sex chromosomes. In consequence a female produces three instead of one class of eggs (see to right of diagram) with respect to X. The results of the fertilization of such a female by a normal red male are shown in the lower part of the diagram.
sperm will make a male if it enters an egg from which both sex chromosomes have been removed. It is therefore not the female-producing sperm, as such, that gives a female under normal conditions, but this sperm plus the sex chromosome already present in the egg that gives an additive result — a female.
(4) In the group of nematode worms belonging especially to the genus Rhabditis, there are some extraor
to 1000 females
SPECIAL CASES OF SEX-INHERITANCE 225
dinary perversions of the sex ratios. The table gives the ratios that Maupas discovered. Not only are the
Diplogaster robustus 0.13 male
Rhabditis guignardi 0. 15 male
Rhabditis dulichura 0.7 male
Rhabditis caussaneli 1.4 males
Rhabditis elyaus 1.5 males
Rhabditis coronata 5.0 males
Rhabditis perrieri 7.0 males
Rhabditis marionii 7.6 males
Rhabditis duthiersi 20.0 males
Rhabditis viguieri 45.0 males
males extremely rare — almost reaching a vanishing point in certain cases — but they have lost the instinct to fertilize the female.
The females, on the other hand, have acquired the power of producing sperm, so that they have passed over into the hermaphroditic state. The behavior and history of the sperm that the females produce has only recently been made out by Miss Eva Kriiger. It is found that a spermatozoon enters each egg and starts the development, but takes no further part in the development (Fig. 108). The egg may be said to be half fertihzed. It is a parthenogenetic egg and produces a female.
(5) Some very high male ratios have been reported by Guyer in cases where birds of very different families have been crossed — the conimon fowl by the guinea hen, individuals of different genera of pheasants bred to each other and to fowls, etc. Hybrids between different genera gave 74 ^ — 13 9 . Hybrids between different species of the same genus 12$ — 18 9. In most of these cases, as Guyer points out, the sex is
226 HEREDITY AND SEX
recorded from the mounted museum specimen which has the male plumage. But it is known that the reproductive organs of hybrids, extreme as these, are generally imperfect and the birds are sterile. It has been
Fig. li Fig. 8. FiR.a Fig- 10. Fig. 11. ^^.,
.^:r^-a^> ;>, '*^-: H»1 1^ i_rf
p.:;.^^-i^::v, -^ m H ^
Fig. 108. — Oogenesis and spermatogenesis of Rhabditis aberrans. 1-5, stages in oogenesis, including incomplete attempt to form one polar body. Eighteen chromosomes in 1 and again in 4 and 5. In 3 the entering sperm seen at right. 6, prophase of first spermatocyte with 8 double and two single chromosomes (sex chromosomes). At the first division (7) the double chromosomes separate, and the two sex chromosomes divide, giving ten chromosomes to each daughter cell (8). At the next division the two sex chromosomes move to opposite poles, giving two female-producing sperm (9 and 10). Rarely one of them may be left at the division plane and lost, so that a male-producing sperm results that accounts for the rare occurrence of males. (After E. Krixger.)
shown that if the ovary of the female bird is removed or deficient, she assumes the plumage of the male. Possibly, therefore, some of these cases may fall under this heading, but it is improbable that they can all be explained in this way. In the cases examined by Guyer himself the hybrids were dissected and all four were found to be males.
SPECIAL CASES OF SEX-INHERITANCE 227
Pearl has recently pointed out that the sex ratio in the Argentine RepubUc varies somewhat according to whether individuals of the same race, or of different races, are the parents. As seen in the following table, the sex ratio of Italian by Italian is 100.77;
Comparison of the Sex Ratios of the Offspring of Pure and
P.E. OF Difference
Italian $ Argentine 9 Italian $ Italian 9
105.72 ±.46 100.77 ±.20
Itahan $ Argentine 9 Argentine $ Argentine 9
105.72 ±.46 103.26 ±.34
Spanish $ Argentine 9 Spanish ^ Spanish 9
106.69 ±.74 105.55 ±.36
Spanish J Argentine 9 Argentine $ Argentine 9
106.69 ±.74 103.26 ±.34
Argentine by Argentine, 103.26 ; but ItaUan by Argentine, 105.72. If, as has so often been found to be the case, a hybrid combination gives a more vigorous progeny, the higher sex ratio of the cross-breed may account for the observed differences, since other data show that the male infant is less viable and the increased vigor of a hybrid combination may increase the chance of survival of the male.
228 HEREDITY AND SEX
(6) We come now to the most perplexing case on record. In frogs the normal sex ratio is approximate equality. Professor Richard Hertwig has found that if the deposition of the eggs is prevented for two to three days (after the eggs have reached the uterus) the proportion of males is enormously increased — in the extreme case all the offspring may be males. By critical experiments Hertwig has shown that the results are not due to the age of the spermatozoa, although in general he is inclined to attribute certain differences in sex-determination to the sperm as well as to the eggs.
The evidence obtained by his pupil, Kuschakewitsch, goes clearly to show that the high male sex ratio is not due to a differential mortality of one sex.
In the following table four experiments (a, h, c, d) are summarized. The interval between each record
a) 47 9 : 32 ^ 9 : 97 ^
/^\ /^^\ /^^\
b) 34 9:47^ 65^:77^ 156 9:194^ 7 9:48^
c)64 9: 6U 101^:139^ 115 9:169^
/IK /'K /'N
d) 55 9:52^ 148 9:87^ 719:70^ 17 9:129^
is written above in hours. In all cases an excess of males is found if the eggs have been kept for several hours before fertilization. In the first (a), second (6), and fourth (d) cases the excess of males is very great. Hertwig attempts to bring his results into line with
SPECIAL CASES OF SEX-INHERITANCE 229
his general hypothesis of nucleo-plasm relation. He holds, for instance, that sex may be determined by the relation between the size of the nucleus and the protoplasm of the cell. As the value of the evidence has been seriously called into question in general, and as there is practically no evidence of any weight in its favor in the present case, I shall not dwell further on the question here. But the excessively high male ratio is evident and positive. How to explain it is difficult to say. It is just possible, I think, that delay may have injured the egg to such an extent that the sperm may start the development but fail to fuse with the egg nucleus. Under these circumstances there is the possibihty that all the frogs would be males.
Miss King has also carried out extensive sets of experiments with toads and frogs. She has studied the eggs and the sperm under many different conditions, such as presence of salt solutions, acids, sugar solutions, cold, and heat. Her results are important, but their interpretation is uncertain. In sugar solutions and in dry fertiUzation she has increased the proportion of males to 114 per 100 9 . The normal sex ratio for the toad is 90 ^ to 100 $ . Whether the solutions have in any sense affected the determination of sex, or acted to favor one class of sperm at the expense of the other remains to be shown, as Miss King herself frankly admits.
In the case of man there are extensive statistics concerning the birth rate. The accompanying tables give some of the results. There are in all parts of the world more males born than females. The excessively high ratios reported from the Balkans (not given here) may be explained on psychological grounds, as failure
HEREDITY AND SEX
to 100 females
Italy ........ 105.8
Russia 105.4 j
to report the birth of a boy is more likely to lead to the imposition of a fine on account of the conscription.
There can be no doubt, however, that slightly more males than females are born. Moreover, if the stillborn infants alone are recorded, surprisingly large ratios occur, as shown in the next table.
Sweden . 135.0
to 100 females
And if abortive births are also taken into account, the ratio is still higher. It seems that the male embryo is not so strong as the female, or else less likely, from other causes, to be born alive.
In many of the domesticated animals also, especially
SPECIAL CASES OF SEX-INHERITANCE 231
the mammals, there is an excess of males at birth, as the next table shows.
Horse 98.31 100 (Busing)
Cattle 107.3 100 (Wilchens)
Sheep 97.7 100 (Irwin)
Pig 111.8 100 (Wilchens)
Rat 105.0 100 (Cuenot)
Dove 105.0 100 (Cuenot)
Hen 94.7 100 (Darwin)
A little later I shall bring forward the evidence that makes probable the view that in man the mechanism for sex-determination is like that in other animals, where two classes of sperm are produced, male- and female-producing. How then can we account in the human race for the excess of eggs that are fertilized by male-producing spermatozoa ? At present we do not know, but we can at least offer certain suggestions that seem plausible.
In mammals the fertilization occurs in the upper parts of the oviduct. In order to reach these parts the sperm by their own activity must traverse a distance relatively great for such small organisms. If the rate of travel is ever so slightly different for the two classes of sperm, a differential sex ratio will occur.
Again, if from any cause, such as disease or alcoholism, one class of sperm is more affected than the other, a disturbance in the sex ratio would be expected.
At present these are only conjectures, but I see no ground for seizing upon any disturbance of the ratio in order to formulate far-reaching conclusions in regard to sex-determination itself. As I pointed out in the beginning of this chapter, we may go
232 HEREDITY AND SEX
wide of the mark if we attempt to draw conclusions concerning the determination of sex itself from deviations such as these in the sex ratio, yet it is the mistake that has been made over and over again. We must look to other methods to give us sufficient evidence as to sex-determination. Fortunately we are now in a position to point to this other evidence with some assurance. With the mechanism itself worked out, we are in a better position to explain slight variations or variables that modify the combinations in this way or in that. i
THE ABANDONED VIEW THAT EXTERNAL CONDITIONS
But before taking up the evidence for sex-determination in man I must briefly consider what I have been bold enough to call the abandoned view that external conditions determine sex.
Let us dismiss at once many of the guesses that have been made. Drelincourt recorded 262 such guesses, and Geddes and Thomson think that this number has since been doubled. Naturally we cannot consider them all, and must confine ourselves to a few that seem to have some basis in fact or experiment.
The supposed influence of food has been utilized in a large number of theories. The early casual evidence of Landois, of Mrs. Treat, and of Gentry has been entirely set aside by the careful observations of Riley, Kellogg and Bell, and Cuenot. In the latter cases the experiments were carried through two or even three generations, and no evidence of any influence of nourishment was found.
SPECIAL CASES OF SEX-INHERITANCE 233
The influence of food in sex-determination in man has often been exploited. It is an ever recurrring episode in the ephemeral Hterature of every period. The most noted case is that of Schenk. In his first book he said starvation produced more females ; in his second book he changed his view and supposed that starvation produces more males.
Perhaps the most fertile source from which this view springs is found in some of the earlier statistical works, especially that of Diising. Dtising tried to show that more girls are born in the better-fed classes of the community, in the poorer classes more boys. The effective difference between these two classes is supposedly one of food ! For instance, he states that the birth-rate for the Swedish nobility is 98 boys to 100 girls, while in the Swedish clergy the birth-rate is 108.6 boys to 100 girls.
Other statistics give exactly opposite results. Punnet t found for London (1901) more girls born amongst the poor than the rich. So many elements enter into these data that it is doubtful if they have much value even in pointing out causes that affect the sex ratio, and it is quite certain that they throw no light on the causes that determine sex.
In other mammals where a sex ratio not dissimilar to that in man exists, extensive experiments on feeding have absolutely failed to produce any influence on the ratio. We have, for instance, Cuenot's experiments with rats, and Schultze's experiments with mice. The conditions of feeding and starvation were much more extreme in some cases than is likely to occur ordinarily, yet the sex ratio remained the same.
Why in the face of this clear evidence do we find
234 HEREDITY AND SEX
zoologists, physicians, and laymen alike perpetually discovering some new relation between food and sex? It is hard to say. Only recently an ItaUan zoologist, Russo, put forward the view that by feeding animals on lecithin more females were produced. He claimed that he could actually detect the two kinds of eggs in the ovary — the female- and the male-producing. It has been shown that his data were selected and not complete ; that repetition of his experiments gave no confirmative results, and probably that one of the two kinds of eggs that he distinguished were eggs about to degenerate and become absorbed.
But the food theories will go on for many years to come — as long as credulity lasts.
Temperature also has been appealed to as a sex factor in one sense or another. R. Hertwig concluded that a lower temperature at the time of fertilization gave more male frogs, but Miss King's observations failed to confirm this. There is the earher work of Maupas on hydatina and the more recent work of von Malsen on Dinophilus apatris. I have already pointed out that Maupas' results have not been confirmed by any of his successors. Even if they had been confirmed they would only have shown that temperature might have an effect in bringing parthenogenesis to an end and instituting sexual reproduction in its stead. In hydatina the sexual female and the male producing individual are one and the same. A more striking case could not be found to show that the environment does not determine sex but may at least change one method of reproduction into another.
There remain von Malsen' s results for dinophilus.
SPECIAL CASES OF SEX-INHERITANCE 235
where large and small eggs are produced by the same female (Fig. 109). The female lays her eggs in clusters, from three to six eggs, as a rule, in each cluster. The large eggs produce females; the small eggs pro
FiG. 109. — Dinophilus gyrociliatus. Females (above and to left) and males (below and to right). Two kinds of eggs shown in middle of lower row. (After Shearer.)
duce rudimentary males that fertiUze the young females as soon as they hatch and before they have left the jelly capsule.
Von Malsen kept the mother at different temperatures, with the results shown in the table. The ratio of small eggs to large eggs changes. But the result
Eggs per Brood
Room temp. 19° C. . Cold, 13° C. . . . Heat, 26° C. ...
202 925 383
327 973 507
1:2,4 1:3,5 1:1,7
5,6 4,2 3,6
236 HEREDITY AND SEX
obviously may only mean that more of the large eggs are likely to be laid at one temperature than at another. In fact, temperature seemed to act so promptly according to Von Malsen's observations that it is very unlikely that it could have had any influence in determining the kind of egg produced, but rather the kind of egg that was more likely to be laid. We may dismiss this case also, I believe, as not showing that sex is determined by temperature.
SEX-DETERMINATION IN MAN
Let us now proceed to examine the evidence that bears on the determination of sex in man. I shall draw on three sources of evidence :
1. Double embryos and identical twins.
2. Sex-linked inheritance in man.
3. Direct observations on the chromosomes.
The familiar case of the Siamese twins is an example of two individuals organically united. A large series of such dual forms is known to pathologists. There are hundreds of recorded cases. In all of these both individuals are of the same sex, i.e. both are males or both are females. There is good evidence to show that these double types have come from a single fertilized egg. They are united in various degrees (Fig. 110) ; only those that have a small connecting region are capable of living. These cases lead directly to the formation of separate individuals, the so-called identical twins.
Galton was one of the first, if not the first, to recognize that there are two kinds of twins — identical twins and ordinary or fraternal twins.
SPECIAL CASES OF SEX-INHERITANCE 237
Identical twins are, as the name implies, extremely alike. They are always of the same sex. There is every presmnption and some collateral evidence to show that they come from one egg after fertilization. On the other hand, amongst ordinary twins a boy and a girl, or two boys and two girls, occur in the ratio expected, i.e. on the basis that their sex is
' *» Ah ai» a> a»i k
81 Bo Bai
Ol - Oil Om
DIAGRAM SHOWING THE INTERRELATIONS OF THE VARIOUS SORTS OF OIPLOPAGI ANO DUPLICATE TWINS, ILLUSTRATIVE OF THE THEORY. ADVANCED IN THIS PAPER. FURTHER EXPLANATION IN THE TEXT.
Fig. 110. — Diagram showing different types of union of double monster
not determined by a common external or internal cause. Since fraternal twins and identical twins show these relations at birth and 'from the fact that they have been in both cases subjected to the same conditions, it follows with great probability that sex in such cases is determined before or at the time of fertilization.
This conclusion finds strong support from the condi
HEREDITY AND SEX
tions that have been made out in the armadillo. Jehring first reported that all the young of a single litter are of the same sex (Fig. 111). The statement has been verified by Newman and by Patterson on a large scale. In addition they have found, first, that only one egg leaves the ovary at each gestative period ; and second, that from the egg four embryos are pro
FiG. 111. — Nine-banded Armadillo. Four identical twins with a common placenta. (After Newman and Patterson.)
duced (Fig. 112). The material out of which they develop separates from the rest of the embryonic tissue at a very early stage. The four embryos are identical quadruplets in the sense that they are more like each other than like the embryos of any other litter, or even more like each other than they are to their own mother.
The second source of evidence concerning sex-deter
SPECIAL CASES OF SEX-INHERITANCE
mination in man is found in the heredity of sex-Unked characters.
The following cases may well serve to illustrate some of the better ascertained characters. The tables are taken from Davenport's book on " Heredity in Relation to Eugenics." The squares indicate males, affected males are black squares ; the heavy circles indicate females, that are supposed to carry the factors, but
Fig. 112. — Nine banded Armadillo. Embryonic blastocyst that has four embryos on it, two of which are seen in figure. (After Newman and Patterson.)
such females do not exhibit the character themselves. Solid black circles stand for affected females.
Haemophilia appears in affected stocks almost exclusively in males (Fig. 113). Such males, mating with normal females, give only normal offspring, but the daughters of such unions if they marry normal males will transmit the disease to half of their sons. Affected females can arise only when a haBmophilious male marries a female carrying haemophilia. If we
HEREDITY AND SEX
SPECIAL CASES OF SEX-INHERITANCE 241
Fig. 114. — Diagram to indicate heredity of color blindness through male. A color-blind male (here black) transmits his defect to his grandsons only. ;
o o cr cf
Fig. 115. — Diagram to indicate heredity of color blindness through female. A color-blind female transmits color blindness to all of her sons, to half of her granddaughters and to half of her grandsons.
HEREDITY AND SEX
substitute white eyes for haemophilia, the scheme already given for white versus red eyes in flies applies to this case. If, for instance, the mother with normal eyes has two X chromosomes (Fig. 114), and the factor for haemophilia is carried by the single X in the male (black X of diagram), the daughter will have one affected X (and in consequence will transmit the factor), but also one normal X which gives normal
6 6 6
Fig. 116. — Pedigree of Ichthyosis from Bramwell. (After Davenport.)
vision. The sons will all be normal, since they get the X chromosomes from their mother. In the next generation, as shown in the diagram (third line), four classes arise, normal females, hybrid females, normal males, and hsemophilious males. Color blindness follows the same scheme, as the above diagrams illustrate (Figs. 114 and 115). In the first diagram the colorblind male is represented by a black eye ; the normal female by an eye without color. The offspring from
SPECIAL CASES OF SEX-INHERITAXCE 243
i— n i
HEREDITY AND SEX
two such individuals are normal, but the color blindness reappears in one-fourth of the grandchildren, and in these only in the males. The reverse mating is shown in the next diagram in which the female is color-blind. She will have color-blind sons and normal daughters (criss-cross inheritance), and all four kinds of grandchildren.
Other cases in man that are said to show sex-linked inheritance are atrophy of the optic nerve, multiple
ciifflfflcniii ii 1
Fig. lis. — Pedigree of night blindness in a negro family from Bordley.
sclerosis, myopia, ichthyosis (Fig. 116), muscular atrophy (Fig. 117), and night-blindness (Fig. 118). There are also other cases in man that appear to come under the same category, but for which the evidence is not so clear.
All these cases of sex-linked -inheritance in man are explained by the assmnption that the factor that produces these characters is carried by the sex chromosome, which is duplex (XX) in the female and simplex (X) in the male. A simpler assumption has not yet been found. If one is fastidious and objects to the
SPECIAL CASES OF SEX-INHERITANCE 245
statement of factors being carried by chromosomes, he has only to say, that if the factors for the characters follow the known distribution of the sex chromosome, the results can be accounted for.
The culmination of the evidence of sex-determination in man is found in a study of the cell structure of the human race itself. Strange as it may seem, we have been longer in doubt concerning the number of chromosomes in man than in any other animal as extensively studied. Four conditions are responsible :
(1) The large number of chromosomes present in man.
(2) The clumping or sticking together of the chromosomes. (3) The difficulty of obtaining fresh material. (4) The possibility that the negro race has half as many chromosomes as the white race.
Two years ago Gu^^er announced the discovery that in all probabihty there exist in man two unpaired chromosomes in the male (Fig. 119) that behave in all respects like that in the typical cases of the sort in insects, where, as we have seen, there are two classes of spermatozoa, differing by the addition of one more chromosome in one class. These produce females ; the lacking class produces males. But Guyer's evidence was not convincing. He found in all 12 chromosomes in one class of sperm and 10 in the other. Montgomery has also studied the same problem, but his account, while confirming the^ number, is in disagreement in regard to the accessory.
Jordan has gone over a number of other mammals, in some of which he thinks that he has found indications at least of two classes of sperm.
Still more recently another investigator, von Wini
246 HEREDITY AND SEX
warter, has attacked the problem (Fig. 120). His material and his methods appear to have been superior to those of his predecessors. His results, while stated with caution and reserve, seem to put the whole question on a safer basis.
His main results are illustrated in the diagram
>r||i;^ ^^^ ^^" ■^■•
^-•* -.-. .»x t?^»:^>
Fig. 119. — Human spermatogenesis according to Guyer. The sex
chromosomes are seen in 6-9.
(Fig. 120). In the male he finds 47 chromosomes. Of these 46 unite at reduction to give 23 double chromosomes — one remains without a mate. At the first reduction division the pairs separate, 23 going to each pole, the unpaired chromosome into one cell only.
SPECIAL CASES OF SEX-INHERITANCE 247
At the next division all the chromos(3mes in the 23 group divide, Ukevvise all in the 24 group divide. There are produced two spermatozoa containing 24
•1. 1'. •
Fig. 120. — Human spermatogenesis according to von Winiwarter, a, spermatogonia! cell with duplex number; h, synapsis ; c, d, e,f, first spermatocytes with haploid number of chromosomes ; g, first spermatocyte division, sex chromosomes (below) in advance of others ; h, two polar plates of later stage ; i, first division completed ; j, second spermatocyte with 23 chromosomes ; k, second spermatocyte ^\^th 24 chromosomes ; I, second spermatocyte division ; m, two polar plates of later stage.
248 HEREDITY AND SEX
chromosomes, and two containing 23 chromosomes; all four sperms having come from the same spermatogonia! cell (Fig. 121).
In the female von Winiwarter had difficulty in determining the number of chromosomes present. His
^e/jc ileler/nuntUcn in Ulan (McnfHfttltr)
Fig. 121. — Diagram of human spermatogenesis. A, spermatogonial cell with 47 chromosomes; B, first spermatocyte with reduced haploid number and sex chromosome (open circle) ; C, first division ; D, two resulting cells = second spermatocytes ; E, division of second spermatocytes ; F, four resulting spermatozoa, two female-producing (above), two male-producing (below).
best counts gave 48 chromosomes for the full or duplex number. These observations fit in with the results from the male.
If these observations are confirmed, they show that in man, as in so many other animals, an internal mechanism exists by which sex is determined. It is futile then to search for environmental changes that
SPECIAL CASES OF SEX-IXHERITANCE 249
might determine sex. At best the environment may sHghtly disturb the regular working out of the two possible combinations that give male or female. Such disturbances may affect the sex ratio but have nothing to do with sex-determination.
Andrews, E. A., 1895. Conjugation in an American Crayfish.
Am. Nat, XXIX. Andrews, E. A., 1904. Breeding Habits of Crayfish. Am. Nat.,
XXXVIII. Andrews, E. A., 1910. Conjugation in the Crayfish Cambarus
affinis. Joivr. Exp. Zool., IX. Arkell, T. R., 1912. Some Data on the Inheritance of Horns in
Sheep. N. H. Agr. Exp. Sta. Bulletin, 160. Arkell, T. R., and C. B. Davenport, 1912. The Nature of the
Inheritance of Horns in Sheep. Science, N. S., XXXV. Arkell, T. R., and C. B. Davenport, 1912. Horns in Sheep as a
Typical Sex-limited Character. Science, N. S., XXXV. VON Baehr, W. B., 1908. Ueber die Bildung der Sexualzellen bei d.
Aphidida^. Zool. Ayiz., XXXIII. VON Baehr, W. B., 1909. Die Oogenese bei einigen \dviparen
Aphiden und die Spermatogenese von Aphis sahceti. Arch. f.
Zellf., III. VON Baehr, W. B., 1912. Contribution a I'etude de la csnyo kinese somatique, de la pseudoreduction et de la reduction.
La Cellule, XXVII. Baitsell, G. a., 1912. Experiments on the Reproduction of the
Hypotrichous Infusoria. Jour. Exp. Zool., XIII. Baltzer, F., 1908. Uber die Grosse und Form der Chromosomen
von Seeigeleiern. Verh. d. deutsch. zool. Ges., 1908. Baltzer, F., 1909. Die Chromosomen von Strongylocentrotus
li\'idus und Echinus microtuberculatus. Aixh. f. Zellf., II. Baltzer, F., 1910. Ueber die Beziehung zwischen dem Chromatin
und der Entwicklung und Vererbungsrichtung bei Echinoder menbastarden. Arch. f. Zellf., V. Baltzer, F., 1911. Zur Kentnis der Mechanik der Kernteilungs figuren. Arch. Entw.-mech. f. d. Org., XXXIII. Bateson, W., 1909. Mendel's Principles of Heredity. Cambridge.
Bateson, W., 1912. Biological Fact and the Structure of Society. Cambridge.
Bateson, W., 1913. Mendel's Principles of Heredity. 3d impression. Cambridge.
Bateson, W., and R. C. Punnett, 1905. Rej). Evol. Contm., 11.
Bateson, W., and R. C. Punnett, 1908. The Heredity of Sex. Science, XXVII.
Bateson, W., and R. C. Punnett, 1911. On the Interrelations of Genetic Factors. Proc. Roy. Soc, LXXXIV.
Bateson, W., and R. C. Punnett, 1911. The Inheritance of the Pecuhar Pigmentation of the Silky Fowl. Jour. Gen., I.
Bateson, W., and R. C. Punnett, 1911. On Gametic Series Involving Reduplication of Certain Terms. Jour. Gen., I.
Baumgartner, W. J., 1912. Observations on the Grylhdse — IV. Copulation. Kans. Univ. Sci. Bull., V.
Baur, E., 1911. Ein Fall von Faktorenkoppelung bei Antirrhinum majus. Vei'h. Jiaturf. Ver. BriXnn, XLIX.
Baur, E., 1912. Vererbungs- und Bastardierungsversuche mit Antirrhinum — II. Faktorenkoppelung. Zeits. Ahst. u. Vererb., VI.
Baur, E., 1912. Ein Fall von geschlechtsbegrenzter Vererbung bei Melandrium album. Zeits. Abst. u. Vererb., VIII.
Beard, J., 1902. The Determination of Sex in Animal Development. Zool. Jahrb. Abt. Anat., XVI.
Beddard, F. E., 1906. Proc. Zool. Soc. London, 1906, II, p. 533.
VAN Beneden, Ed., and Ch. Julin, 1884. La spermatogenese chez Tascaride megalocephale. Bull, de Vacad. roy. de Belgique. Annee 53, 3°^^ Ser., T. VII.
Berry, E. H., 1906. The "Accessory Chromosome" in Epeira. Biol. Bull, XL
Blackman, M. W., 1905. The Spermatogenesis of Myriapods. III. Bull. Mus. Corny. Zool., Harvard College, XLVIII.
Blakeslee, a. F., 1904. Sexual Reproduction in the Mucorineae. Proc. Amer. Acad. Arts and Sci., XL.
Blakeslee, A. F., 1904. Zygospore Formation a Sexual Process. Science, XIX.
Blakeslee, A. F., 1906. Differentiation of Sex in Thallus Gametophyte and Sporophyte. Bot. Gaz., XLII.
Blakeslee, a. F., 1908. Sexual Condition in Fegatella. Bot.
Gaz., XL VI. Boring, A. M., 1909. A Small Chromosome in Ascaris megalo cephala. Arch. f. Zellf., IV. BovERi, Th., 1907. Zellen Studien. Die Entwicklung dispermer
Seeigel-Eier, etc. Jena. BovERi, Th., 1908. Ueber die Beziehung des Chromatins zur
Geschlechtbestimmung. Sitz. Phijs.-Med. GeselL Wurzburg.
Dez., 1908. BovERi, Th., 1909. Die Blastomerenkerne von Ascaris megalo cephala und die Theorie der Chromosomen-Individualitat.
Arch. Zellf., III. BovERi, Th., 1909. Ul3er Geschlechtschromosomen" bei Ne matoden. Arch. Zellf., IV. BovERi, Th., 1911. Ueber das Verhalten der Geschechtschro mosomen bei Hermaphroditismus. Verh. Phijs.-Med. GeselL
Wurzburg, XLI. Brauer, a., 1893. Zur Kenntniss der Spermatogenese von Ascaris
megalocephala. Arch. mikr. Anal., XLI I. Bresca, G., 1910. Experiment elle Untersuchungen uber die
sekundaren Sexualcharaktere der Tritonen. Arch. Entw. mech., XXIX. Brewster, E. T., 1906. Note on the Determination of Sex in
Man. Am. Anthropol., VIII. Bridges, C. B., 1913. Partial Sex-Linkage in the Pigeon. Science,
XXXVII. BucHNER, Paul, 1911. Ueber hermaphrodite Seesterne. Zool.
Anz., XXXVIII. BuGNiON, E., 1910. Les Cellules Sexuelles et la Determination du
Sexe. Bull. Soc. Vaudoise Sci. Nat., LXVI. BuRGEFF, H., 1913. Ueber Sexualitat, Variabihtat und Vererbung
bei Phycomyces nitens. Ber. deutsch. Bot. GeselL, X. Calkins, G. N., 1902. Studies on the Life-History of Protozoa.
III. Biol. Bull., III.
Calkins, G. N., 1904. Studies on the Life-History of Protozoa.
IV. Jour. Exp. ZooL, I.
Calkins, G. N., 1911. Protozoon Germ Plasm. Pop. Sci. Monthly. Calkins, G. N., 1913. Further Light on the Conjugation of Paramecium. Proc. Soc. Exp. Biol. Med., X.
CalkijJs, G. N., and C. C. Lieb, 1902. Studies on the Life-History of Protozoa, II. Arch. Protist., 1902.
Carmichael, E. S., and F. H. A. Marshall, 1908. On the Occurrence of Compensatory Hypertrophy in the Ovary. Jour. Physiol. XXXVI.
Castle, W. E., 1903. The Heredity of Sex. Bull. Mus. Comp. ZooL, Harvard College, XL.
Castle, W. E., 1909. A Mendehan View of Sex Heredity. Science, XXIX.
Castle, W. E., 1910. The Effect of Selection upon Mendehan Characters Manifested in One Sex only. Jour. Exp. ZooL, VIII.
Castle, W. E., 1911. Double-mating of Silkworm Moths. Science, XXXIII.
Castle, W. E., 1911. Heredity in Relation to Evolution and Animal Breeding. New York.
Castle, W. E., 1912. Are Horns in Sheep a Sex-limited Character ? Science, XXXV.
Castle, W. E., 1913. Simplification of Mendehan Formulae. Am. Nat., XLVII.
Castle, W. E., F. W. Carpenter, A. H. Clark, S. 0. Mast, and W. M. Barrows, 1906. The Effects of Inbreeding, Crossbreeding, and Selection upon the Fertility and Variability of Drosophila. Proc. Am. Acad. Arts and Sci., XLI.
Castle, W. E., and J. C. Phillips, 1909. A Successful Ovarian Transplantation in the Guinea-pig, etc. Science, XXX.
Chidester, F. E., 1911. The Mating Habits of Four Species of the Brachyura. Biol. Bull., XXI.
Chopard, L., 1912. Note sur un cas de g^mandromorphisme chez Forficula auricularia. Arch. ZooL Exp. et Gen., Ser. 5, T, X.
Cole, L. J., 1912. A Case of Sex-linked Inheritance in the Domestic Pigeon. Science, XXXVI.
Collins, G. N., 1912. Gametic Coupling as a Cause of Correlations. Am. Nat., XLVI.
CoLTON, H. S., 1912. Lymna^a columella and Self-fertilization. Proc. Acad. Nat. Sci. Phil.
CoNKLiN, E. G., 1906. Sex-differentiation in Dinophilus. Science^ XXIV.
Cook, M. H., 1910. Spermatogenesis in Lepidoptera. Proc. Acad. Nat. Sci. Phil.
CoRRENS, C, 1907. Zur Kenntnis der Geschlechtsformen polygamer Bltitenpflanzen und ihrer Beeinflussbarkeit. Jahrb. f. Wiss. Bot., XLIV.
CoRRENS, C, 1907. Die Bestimmung und Vererbung des Geschlechts. Berlin.
CoRRENS, C., 1908. Weitere Untersuchungen uber die Geschlechtsformen polygamer Bltitenpflanzen und ihre Beeinflussbarkeit. Jahrb. f. wiss. Bot., XLV.
CoRRENS, C, 1908. Die Rolle der Mannhchen Keimzellen bei der Geschlechtsbestimmung der gynodioecischen Pflanzen. Ber. deutsch. Bot. Ges., XXVI.
CoRRENS, C, 1908. Weitere Untersuchungen ueber die Geschlechtsformen polygamer Bliitenpflanzen und ihre Beeinflussbarkeit. Jahrb. f. wiss. Bot., XLV.
CoRRENS, C., 1912. Selbststerilitat und Individualstoffe. Fests. ■ Med. Nat. Gesell. 84. Versam. deut. Natur. Aerzte.
CoRRENS, C, and R. Goldschmidt, 1913. Die Vererbung und Bestimmung des Geschlechts. Gesamtsitz. ] naturw. mediz. Hauptg. 84. Vers, deuts. Naturf. u. Aerzte in Miinster.
Cue'not, L., 1899. Sur la determination du sexe chez les animaux. Bidl. Scient. France Belg., XXXII.
Cunningham, J. T., 1908. The Heredity of Secondary Sexual • Characters in Relation to Hormones. Arch. f. Entw.-mech.,
Darling, C. A., 1909. Sex in Dioecious Plants. Bull. Tor. Bot.
Darwin, C, 1886. The Descent of Man, and Selection in Relation to Sex. New York.
Darwin, C, 1889. Different Forms of Flowers on Plants of the Same Species. New Yort.
Darwin, C, 1895. Cross and Self-Fertihzation in the Vegetable Kingdom. New York.
Davenport, C. B., 1906. Inheritance in Poultry. Carnegie Inst. Wash., pub. 53.
Davenport, C. B., 1909. Inheritance of Characteristics in Domestic Fowl. Carnegie hist. Wash., pub. 121.
Davenport, C. B., 1911. Heredity in Relation to Eugenics. New
York. Davenport, C. B., 1911. Another Case of Sex-limited Heredity
in Poultry. Proc. Soc. Exp. Biol. Med., IX. Davenport, C. B., 1912. Sex-limited Inheritance in Poultry.
Jour. Exp. Zool., XIII. Dederer, p. H., 1907. Spermatogenesis in Philosamia cynthia.
Biol. Bull., XIII. Delage, Y., 1908. Les Idees nouvelles sur la Parthenogenese
experimentale. La Revue des Idees, 50. Delcourt, A.,andE. GuYENOT, 1911. Genetique et Milieu. Bull.
Scient. France Belg., XLV. Della Valle, p., 1913. Die Morphologie des Zellkerns und die
Physik der Kolloide. Zeits. Chem. Industr. Kolloide, XII. Dexter, J. S., 1912. On Couphng of Certain Sex-Hnked Characters in Drosophila. Biol. Bull., XXIII. DoDDS, G. S., 1910. Segregation of the Germ-Cells of the Teleost,
Lophius. Jour. Morph., XXI. DoNCASTER, L., 1907. Inheritance and Sex in Abraxas grossu lariata. Nature, LXXVI. DoNCASTER, L., 1907. Gametogenesis and Fertihzation in Nema tus ribesii. Q. J. M. S., LI. DoNCASTER, L., 1908. On Sex-inheritance in the Moth, Abraxas
grossulariata and its var. lacticolor. 4^h Rep. Evol. Comm.,
R. Soc. Lond. DoNCASTER, L., 1908. Animal Parthenogenesis. Sci. Progr. DoNCASTER, L., 1909. Recent Work on the Determination of Sex.
Sci. Progr., XIII. DoNCASTER, L., 1910. Gametogenesis of the Gall-fly, Neuroterus
lenticularis (Spathegaster baccarum). Part L Proc. Roy.
Soc, B, LXXXII. DoNCASTER, L., 1911. Gametogenesis of the Gall-fly, Neuroterus
lenticularis. Part II. Proc. Roy. Soc, LXXXIII. DoNCASTER, L., 1911. Note on the Inheritance of Characters in
which Dominance appears to be Influenced by Sex. Jour.
Genet., I. DoNCASTER, L., 1911. Some Stages in the Spermatogenesis of
Abraxas grossulariata and its var. lacticolor. Jour. Geiiet., I.
DoNCASTER, L., 1912. The Chromosomes in the Oogenesis and
Spermatogenesis of Pieris brassicae, and in the Oogenesis of
Abraxas grossulariata. Jour. Geiiet., II. DoNCASTER, L., 1912. Note on the Chromosomes in Oogenesis
'and Spermatogenesis of the White Butterfly, Pieris brassicae.
Proc. Camb. Phil. Soc, XVI. DoNCASTER, L., and G. Gray, 1911. Cytological Observations on
Cross-fertihzed Echinoderm Eggs. Proc. Camb. Phil. Soc,
XVI. DoNCASTER, L., and F. H. A. Marshall, 1910. The Effects of
One-sided Ovariotomy on the Sex of the Offspring. Jour.
Genet., I. DoNCASTER, L., and G. H. Raynor, 1906. Breeding Experiments
with Lepidoptera. Proc. Zool. Soc. Lond. Drew, G. A., 1911. Sexual Activities of the Squid, Lohgo Pealii
(Hes.). I. Copulation, Egg-laying and Fertihzation. Jour.
Morph., XXII. Durham, F. M., 1911. Further Experiments on the Inheritance of
Coat Colour in Mice. Jour. Genet., I. Durham, F. M., and D. E. C. Marry at, 1908. Note on the Inheritance of Sex in Canaries. 4th Rep. Evol. Comm., Roy.
Soc. Lond. East, E. M., 1910. Notes on an Experiment concerning the Nature of Unit Characters. Science, XXXII. East, E. M., 1910. The Role of Hybridization in Plant Breeding.
Pop. Sci. Mon., Oct., 1910. East, E. M., 1911. The Genotype Hypothesis and Hybridization,
Am. Nat., XLV. East, E. M., 1912. A Study of Hybrids Between Nicotiana
bigelovii and N. quadrivalvis. Bot. Gaz., LIII. East, E. M., and H. K. Hayes, 1911. Inheritance in Maize.
Conn. Exp. Sta. Bidl, 167. East, E. M., and H. K. Hayes, 1912. Heterozygosis in Evolution
and in Plant Breeding. U. S. Dept. Agric, Bureau Plant
Ind. Bull. 243. Edwards, C. L., 1910. The Sex-determining Chromosomes in
Ascaris. Scierice, XXXI. Emerson, R. A., 1909. Inheritance of Color in the Seeds of the
Common Bean, Phaseolus vulgaris. Ann. Rep. Nebr. Agr.
Exp. Sta., XXII. Emerson, R. A., 1911. Morgan on Coupling vs. Random Segregation. Science, XXXIV. Emerson, R. A., 1911. Genetic Correlation and Spurious Allelomorphism in Maize. Ann. Rep. Nebr. Agr. Exp. Sta.,
XXIV. Federley, H., 1911. Vererbungsstudien an der Lepidopteren Gattung Pygsera. Arch. Rass. GeselL, III. Fere, C, 1898. Experiences relatives aux rapports homosexuels
chez les hammetons. C. R. Soc. Biol., V. Fere, C, 1898. Experiences relatives a I'instinct sexuel chez le
bombyx du murier. C. R. Soc. Biol., V. FiCK, R., 1907. Uber die Vererbungssubstanz. Arch. Anat. u.
Phys., Anat. Abt. Foot, K., and E. C. Strobell, 1913. Preliminary Note on the
Results of Crossing Two Hemipterous Species, etc. Biol.
Bull, XXIV. Fowler, G. H., 1894. Notes on some Specimens of Antlers of the
Fallow Deer, etc. Proc. Zool. Soc. Lond., 1894. Frolowa, S., 1912. Idiochromosomen bei Ascaris megalocephala.
Arch. Zellf., IX. Geddes, p., and J. A. Thomson, 1889. The Evolution of Sex.
London. Gerould, J. H., 1911. The Inheritance of Polymorphism and Sex
in Colias philodice. Am. Nat., XLV. Goldschmidt, R., 1911. Einfiihrung in die Vererbungswissen schaft. Leipzig. Goldschmidt, R., 1912. Erbhchkeitsstudien an Schmetterlingen.
I, 1. Zeits. Abst. Vererb., VII. Goldschmidt, R., 1912. Bemerkungen zur Vererbung des Ge schlechtspolymorphismus. Zeits. Abst. Vererb., VIII. Goldschmidt, R., 1913. Zuchtversuche mit Enten. I. Zeits.
Abst. Vererb., III. GooDALE, H. D., 1909. Sex and its Relation to the Barring Factor
in Poultry. Science, XXIX. GooDALE, H. D., 1910. Breeding Experiments in Poultry. Proc.
Soc. Exp. Biol. Med., VII.
GooDALE, H. D., 1910. Some Results of Castration in Ducks.
Biol. Bull, XX. GooDALE, H. D., 1911. Studies on Hybrid Ducks. Jour. Exp.
ZooL, X. GooDALE, H. D., 1911. Sex-limited Inheritance and Sexual Dimorphism in Poultry. Science, XXXIII. Good ALE, H. D., 1913. Castration in Relation to the Secondary
Sexual Characters of Brown Leghorns. Am. Nat., XLVIL Gregory, R. P., 1911. Experiments with Primula sinensis. Jour.
Genet., I. Gregory, R. P., 1911. On Gametic Couphng and Repulsion in
Primula sinensis. Proc. Roy. Soc, LXXXIV. Gross, J., 1912. Heterochromosomen und Geschlechtsbestimmung
bei Insekten. Zodl.Jahrb.,XXKlI. Gruenberg, B. C, 1912. Physiological Sex-determination. Science,
N. S., XXXV. GuDERNATSCH, J. F., 1911. Hemiapliroditismus verus in Man.
Am. Jour. Anat., XI. GuDERNATSCH, J. F., 1912. Feeding Experiments on Tadpoles. I.
Arch. Entw.-mech., XXXV. GuDERNATSCH, J. F., 1912. Futterungsvcrsuche an Amphibien larven. Zentrbl. f. Physiol., XXVI. GuLiCK, A., 1911. Ueber die Geschlechtschromosomen bei einigen
Nematoden. Arch. f. Zellf.,\l. GuYER, M. F., 1902. Hybridism and the Germ Cell. Univ. of
Cincinnati Bull., No. 21. GuYER, M. F., 1903. The Germ Cell and the Results of Mendel.
Cincinnati Lancet-Clinic. GuYER, M. F., 1905. Guinea-Chicken Hybrids. Science, N. S.,
XXI. GuYER, M. F., 1905. Notes on Cross-bred Chickens. Science,
N. S., XXI. GuYER, M. F., 1907. Do Offspring Inherit Equally from Each
Parent? Science, ISi. ^., XXY. GuYER, M. F., 1909. Atavism in Guinea-Chicken Hybrids. Jour.
Exp. ZooL, VII. GuYER, M. F., 1909. La Livree du Plumage chez les Hybrides
de Pintade et de Poule. Bull. Mus. d'hist. nat.
GuYER, M. F., 1909. The Spermatogenesis of the Domestic
Chicken. Anat. Anz., XXXIV. GuYER, M. F., 1909. The Spermatogenesis of the Domestic
Guinea. Anat. Anz., XXXIV. GuYER, M. F., 1909. Deficiencies of the Chromosome Theory of
Heredity. University Studies (Cincinnati), Series II, Vol. V. GuYER, M. F., 1909. On the Sex of Hybrid Birds. Biol. Bull,
XVI. GuYER, M. F., 1910. Accessory Chromosomes in Man. Biol.
Bull, XIX. GuYER, M. F., 1911. Nucleus and Cytoplasm in Heredity. Am.
Nat., XLV. Hadley, p. B., 1910. Sex-limited Inheritance. Science, XXXII. Hagedoorn, a. L., 1909. Mendelian Inheritance of Sex. Arch. f.
Entw.-mech., XXVIII. Hagedoorn, A. L., 1912. The Genetic Factors in the Development of the House Mouse, etc. Zeits. Abst. Vererb., VI. Hartley, C. P., E. B., Brown, C. H., Kyle, and L. L. Zook, 1912.
Cross-breeding Corn. U. S. Dept. Agr. Bull., 218. Hartman, F. a., 1913. Variations in the Size of Chromosomes.
Biol. Bull, XXIV. Hasper, M., 1911. Zur Entwicklung der Geschlechtsorgane von
Chironomus. Zool Jahrb., Abt. Anal, XXXI. Heape, W., 1897. Further Note on the Transplantation and
Growth of Mammalian Ova within a Uterine Foster-mother.
Proc. Roy. Soc, LXII. Heape, W., 1899. Note on the Fertility of Different Breeds of
Sheep. Proc. Roy. Soc, LXV. Heape, W., 1905. Ovulation and Degeneration of Ova in the
Rabbit. Proc. Roy. Soc, B, LXXVI. Heape, W., 1907. Notes on the Proportion of the Sexes in Dogs.
Proc Camb. Phil Soc, XIV. Heape, W., 1907. Note on the Influence of Extraneous Forces
upon the Proportion of the Sexes produced by Canaries,
Proc. Camb. Phil Soc, XIV. Heape, W., 1908. Note on Russo's Attempt to show Differentiation of Sex in the Ovarian Ova of the Rabbit. Proc Camb.
Phil Soc, XIV.
Heape, W., 1908. The Proportions of the Sexes produced by
Whites and Colored Peoples in Cuba. Phil. Trans. Roy.
Soc. Lond., Series B, Vol. 200. Heider, K., 1906. Vererbung und Chromosomen. Jena. Henking, H., 1891. Untersuchungen ueber die ersten Entwick lungsvorgange in den Eiern der Insekten. Zeits. f. iviss. Zool., LI. Herbst, C, 1909. Vererbungstudien VI. Arch. Entw.-mech.,
XXVII. Hertwig, O., 1890. Vergleich der Ei und Samenbildung bei
Nematoden. Arch. mikr. Anat., XXXVI. Hertwig, R., 1906. Ueber Knospung und Geschlechtsentwicke lung von Hydra fusca. Festschr. f. J. Rosenthal. Leipzig. Hertwig, R., 1907. Uber den Chromidialapparat und den
Duahsmus der Kernsubstanzen. Sitz. her. Gesell. Morph. und
Phys. in MiXnchen. 1907. Hertwig, R., 1907. Untersuchungen uber das Sexuahtatsproblem.
III. Teil. Verh. Deutsch. Zool. Gesell. Hertwig, R., 1912. Uber den derzeitigen Stand des Sexualitats problems nebst eigenen Untersuchungen. Biol. Centr.,
XXXII. Holding, R. E., 1905. Exhibition of, and Remarks upon, a Series
of the First Year Antlers of Certain Deer. Proc. Zool. Soc.
Loud., II. Holmes, S. J., 1903. Sex Recognition among Amphipods. Biol.
Bull, V. Janda, v., 1912. Die Regeneration der Geschlechtsorgane bei
Criodrilus lacuum. Arch. Entw.-mech., XXXIV. Jannsens, F. a., 1901. La spermatogenese chez les tritons. La
Cellule, XIX. Jannsens, F. A., 1905. Evolution des Auxocytes males du Batra coseps attenuatus. La Cellule, XXII. Jannsens, F. A., 1909. La theorie de la chiasmatypie. Nou velle interpretation des cineses de maturation. La Celhde,
XXV. Jannsens, F. A., and R. Dumez, 1903. L'element nucleinien
pendant les cineses de maturation des spermatocytes chez
Batracoseps attenuatus et Plethedon cinereus. La Cellule,
Jennings, H. S., 1908. Heredity, Variation and Evolution in
Protozoa, II. Proc. Am. Phil. Soc, XLVII. Jennings, H. S., 1909. Heredity and Variation in the Simplest
Organisms. Amer. Nat., XLIII. Jennings, H. S., 1910. Experimental Evidence of the Effectiveness of Selection. Amer. Nat., XLIV. Jennings, H. S., 1911. Assortative Mating, Variability and Inheritance of Size in the Conjugation of Paramoecium. Jour.
Exp. Zool, XI. Jennings, H. S., 1911. Pure Lines in the Study of Genetics in
Lower Organisms. Amer. Nat., XLV. Jennings, H. S., 1913. The Effect of Conjugation in Paramecium.
Jour. Exp. Zool., XIV. Jennings, H. S., and G. T. Hargitt, 1910. Characteristics of the
Diverse Races of Paramecium. Jotir. Morph., XXI. Jennings, H. S., and K. S. Lashley, 1913. Biparental Inheritance
and the Question of Sexuahty in Paramecium. Jour. Exp.
Zool, XIV. Johannsen, W., 1909. Elemente der exakten Erblichkeitslehre.
Jena. Johannsen, W., 1911. The Genotype Conception of Heredity.
Am. Nat., XLV. Jones, W. N., 1912. Species Hybrids of Digitalis. Jour. Genet.,
11. Kahle, W., 1908. Die Psedogenesis der Cecidomyiden. Stuttgart. Keeble, F., and C. Pellew, 1910. The Mode of Inheritance of
Stature and of Time of Flowering in Peas (Pisum sativum).
Jour. Genet., I. Kellogg, V. L., 1907. Some Silkworm Moth Reflexes. Biol.
Bull, XII. Kellogg, V. L., 1907. Artificial Parthenogenesis in the Silkworm.
Biol. Bull, XIV. Kellogg, V. L., 1911. An Experiment in Double Mating. Science,
XXXIII. King, H. D., 1907. Food as a Factor in the Determination of Sex
in Amphibians. Biol. Bull., XIII. King, H. D., 1909. Studies on Sex-Determination in Amphibians.
11. Biol Bull, XVI.
King, H. D., 1910. Temperature as a Factor in the Determination
of Sex in Amphibians. Biol. Bull., XVIII. King, H. D., 1910. Some Anomalies in the Genital Organs of
Bufo lentiginosus and their Probable Significance. Am.
Jour. Anat., X. King, H. D., 1911. Studies on Sex-Determination in Amphibians.
IV. Biol Bull, XX.
King, H. D., 1911. The Sex Ratio in Hybrid Rats. Biol Bull,
XXI. King, H. D., 1912. Dimorphism in the Spermatozoa of Necturus
maculosus. Anat. Rec, VI. King, H. D., 1912. Studies on Sex-Determination in Amphibians.
V. Jour. Exp. Zool, XII.
Kopec, S., 1911. Untersuchungen liber Kastration und Transplantation bei Schmetterhngen. Arch. Entw.-mech., XXXIII.
Krtjger, Eva, 1912. Die phylogenetische Entwicklung der Keimzellenbildung einer freilebenden Rhabditis. Zool Anz., XL.
KuscHAKEWiTSCH, S., 1910. Die Entwickelungsgeschichte der Keimdriisen von Rana esculenta. Festschr. f. R. Heriwig, Bd. II, 1910. Jena.
KuscHAKEWiTSCH, S., 1911. Eiu Fall von Hermaphroditismus lateralis verus bei Rana esculenta. Anal Anz., XXXVIII.
KUSCHAKEWITSCH. S., 1911. Erklaruug zuj* Notiz von T. H. Morgan: "Is the female frog heterozj^gous in regard to sexdetermination?" Anat. Anz., XXXIX.
Lang, A., 1912. Vererbungswissenschaftliche Miszellen. Zeits. Ahst. Vererb., VIII.
VON Lenhossek, 1903. Das Problem der geschlechtsbestimmenden Ursachen. Jena, 1903.
Little, C. C, 1912. Preliminary Note on the Occurrence of a Sexlimited Character in Cats. Science, XXXV.
LoEB, J., 1908. Hervorrufung der Membranbildung, etc. Arch. GesellPhys.,CXXII.
LoEB, J., 1908. Entwicklungserregung unbefruchtete Annehdeneier, etc. Arch. Gesell Phys., CXXII.
LoEB, J., 1909. Die Chemische Entwicklungserregung des tierischen Eies. Berlin.
LoEB, J., 1911. The Role of Salts in the Preservation of Life.
Science, XXXIV. LoEB, J., 1912. Heredity in Heterogeneous Hybrids. Jour.
Morph., XXIII. LoEB, J., and F. W. Bancroft, 1911. Some Experiments
on the Production of Mutants in Drosophila. Science,
XXXIII. LoEB, J., and F. W. Bancroft, 1913. The Sex of a Parthenogenetic
Tadpole and Frog. Jour. Exp. Zool, XIV. LoEB, J., und H., Wasteneys, 1911. Die Beeinfliissung der
Entwicklung, etc. Bioch. Zeits., XXXVII. Loeb, J., und H. Wasteneys, 1911. Weitere Bemerkungen iiber
den Zusammenhang zwischen Oxydationsgrosse und Cytolyse
der Seeigeleier. Bioch. Zeits., XXXI. Lutz, a. M., 1912. Triploid Mutants in Oenothera. Biol. Centr.,
XXXII. Lutz, F. E., 1911. Experiments with Drosophila ampelophila
concerning Evolution. Carnegie Inst. Wash., pub. 143. Lutz, F. E., 1913. Experiments concerning the Sexual Difference
in the Wing Length of Drosophila ampelophila. Jour. Exp.
Zool, XIV. McClendon, J. F., 1910. On the Effect of External Conditions
on the Reproduction of Daphnia. Am. Nat., XLIV. McClung, C. E., 1902. The Accessory Chromosome — Sex Determinant? Biol. Bull., 111. McClung, C. E., 1902. Notes on the Accessory Chromosome.
Anat. Anz.,XX. McClung, C. E., 1905. The Chromosome Complex of Orthopteran
Spermatocytes. Biol. Bull., IX. McCooK, H. C, 1893. American Spiders and their Spinning
Work. 3 vols. Philadelphia. McCracken, I., 1909. Heredity of the Race-characters. Univol tinism, etc., in the Silkworm. Jour. Exp. Zool., VII. Mark, E. L., and U. Copeland, 1907. Maturation Stages in the
Spermatogenesis of Vespa maculata. Proc. Am. Acad. Arts
and Sci., XLIII. Marshall, F. H. A., 1908. The Effects of Environment and
Nutrition upon Fertility. Sci. Progr., VII.
Marshall, F. H. A., 1912. On the Effects of Castration and
Ovariotomy on Sheep. Proc. Roy. Soc, LXXXV. Marshall, F. H. A., and W. R. Pell, 1910. Fatness" as a Cause
of Sterility. Jour. Agri. Sci., III. Mast, S. 0., 1912. Behaviour of Fire-fiies (Photinus pyralis?)
with Special Reference to the Problem of Orientation. Jour.
An. Behav., II. Mayer, A. G., 1900. On the Mating Instinct in Moths. Ann.
Mag. Nat. Hist., V. Mayer, A. G., and C. G. Soule, 1906. Some Reactions of Caterpillars and Moths. Jour. Exp. ZooL, III. DE Meijere, J. C. H., 1910. Ueber Jacobsons Zlichtungsversuche
beztiglich des Polymorphismus von Papilio Memnon. Zeits.
Abst. Vererb., III. DE Meijere, J. C. H., 1910. Ueber getrennte Vererbung der
Geschlechter. Biol. Centr., XXX. DE Meijere, J. C. H., 1911. Uber getrennte Vererbung der Geschlechter. Arch. Rass. GeselL, VIII. Meisenheimer, J., 1908. Uber den Zusammenhang von Ge schlechtsdriisen und sekundaren Geschlechtsmerkmalen bei den
Arthropoden. Verh. d. deut&ch. Zool. GeselL, 1908. Meisenheimer, J., 1909. Experimentelle Studien zur Soma- und
Geschlechtsdifferenzierung, I. Jena, 1909. Meisenheimer, J., 1912. Experimentelle Studien zur Soma und
Geschlechtsdifferenzierung. Fests. zum 60 Geburtstage von
Dr. J. W. Spengel III. Mendel, G., 1865. Versuche iiber Pflanzen-Hybriden. Verh.
d. Naturf. Vereins in Briinn, IV. Meves, Fr., 1903. Richtungskorperbildung in der Spermato genese. Mittheil. f. d. Verein Schles.- Hoist. Aerzte, XI. Meves, F., 1907. Die Spermatocytenteilungen bei der Honigbiene,
etc. Arch. mikr. Anat., LXX.Meves, Fr., and J. Duesberg, 1908. Die Spermatocytenteilung
bei der Hornisse. Arch. mikr. Anat., LXXI. Meyns, R., 1912. Transplantation embryonaler und jugend licher Keimdriisen u. s. w. Arch. mikr. Anat., LXXIX. MoENKHAUs, W. J., 1910. Cross FertiUzation among Fishes. Proc,
Ind. Acad. Sci,
MoENKHAUs, W. J., 1911. Effects of Inbreeding, etc., in Dro sophila ampelophila. Jour. Morph., XXII. Montgomery, T. H., 1903. Studies on the Habits of Spiders,
Particularly those of the Mating Period. Proc. Acad. Nat. Sci.
Phila. Montgomery, T. H., Jr., 1905. The Spermatogenesis of Syrbula
and Lycosa, with General Considerations upon Chromosome
Reduction, etc. Proc. Acad. Nat. Sci. Phil., 1905. Montgomery, T. H., Jr., 1906. Chromosomes in the Spermatogenesis of Hemiptera and Heteroptera. Trans. Am. Phil.
Soc, XXI. Montgomery, T. H., Jr., 1906. The Terminology of Aberrant
Chromosomes and their Behavior in certain Hemiptera.
Science, XXIII. Montgomery, T. H., Jr., 1906. On Reproduction, Animal Life
Cycles, and the Biological Unit, Trans. Tex. Acad. Sci.,
IX. Montgomery, T. H., Jr., 1907. On Parthenogenesis in Spiders.
Biol. Bull, XIII. Montgomery, T. H., Jr., 1908. The Sex-ratio and Cocooning Habits
of an Aranead and the Genesis of Sex-ratios. Jour. Exp.
Zool, V. Montgomery, T. H., Jr., 1910. The Cellular Basis of the Determination of Sex. International Clinics, Vol. I. Montgomery, T. H., 1910. The Significance of the Courtship and
Secondary Sexual Characters of Araneads. Am. Nat., XXXIV. Montgomery, T. H., 1910. Further Studies on the Activities of
Araneads. II. Proc. Acad. Nat. Sci. Phila., 1909. Montgomery, T. H., 1912. Human Spermatogenesis. Jour.
Acad. Nat. Sci. Phila., XV. Morgan, T. H., 1903. Recent Theories in Regard to the Determination of Sex. Pop. Sci. Mon., 1903. Morgan, T. H., 1905. Ziegler's Theory of Sex-determination and
an Alternative Point of View. Science, XXII. Morgan, T. H., 1905. An Alternative Interpretation of the Origin
of Gynandromorphous Insects. Science, XXI. Morgan, T. H., 1906. The Male and Female Eggs of Phylloxerans
of the Hickories. Biol. Bull., X.
Morgan, T. H., 1907. Experimental Zoology. New York. Morgan, T. H., 1907. The Cause of Gynandromorphism in Insects.
Am. Nat., XLI. Morgan, T. H., 1907. The Biological Significance and Control
of Sex. Science, XXV. Morgan, T. H., 1908. The Production of two kinds of Spermatozoa in Phylloxerans. Proc. Soc. Exp. Biol, and Med., V. Morgan, T. H., 1909. Sex-Determination and Parthenogenesis in
Phylloxerans and Aphids. Science, XXIX. Morgan, T. H., 1909. Are the Drone Eggs of the Honey Bee
Fertihzed? Am. Nat., XLIII. Morgan, T. H., 1909. Hybridology and Gynandromorphism.
Am. Nat., XLIII. Morgan, T. H., 1909. A Biological and Cytological Study of
Sex-Determination in Phylloxerans and Aphids. Jour. Exp.
Zool, VII. Morgan, T. H., 1910. Sex-hmited Inheritance in Drosophila.
Science, XXXII. Morgan, T. H., 1910. Hybridization in a Mutating Period in
Drosophila. Proc. Soc. Exp. Biol, and Med., VII. Morgan, T. H., 1910. The Chromosomes in the Parthenogenetic
and Sexual Eggs of Phylloxerans and Aphids. Proc. Soc.
Exp. Biol, and Med., VII. Morgan, T. H., 1910. Chromosomes and Heredity. Am. Nat.,
XLIV. Morgan, T. H., 1910. The Method of Inheritance of two Sexlimited Characters in the Same Animal. Pi'oc. Soc. Exp.
Biol. Med., VIII. Morgan, T. H., 1911. An Attempt to analyze the Constitution
of the Chromosomes on the Basis of Sex-limited Inheritance
in Drosophila. Jour. E.tp. Zool., XL Morgan, T. H., 1911. The Application of the Conception of
Pure Lines to Sex-limited Inheritance and to Sexual Dimorphism. Am. Nat., XLV. Morgan, T. H., 1911. A Dominant Sex-limited Character. Proc.
Soc. Exp. Biol. Med., IX. Morgan, T. H., 1911. An Alteration of the Sex-ratio induced by
Hybridization. Proc. Soc. Exp. Biol, and Med., VIII.
Morgan, T. H., 1911. Is the Female Frog Heterozygous in regard to Sex-determination? Am. Nat., XLV.
Morgan, T. H., 1911. Random Segregation vs. Coupling in Mendelian Inheritance. Science, XXXIV.
Morgan, T. H., 1911. Chromosomes and Associative Inheritance. Science, XXXIV.
Morgan. T. H., 1911. The Origin of Nine Wing-mutations in Drosophila. Science, XXXIII.
Morgan, T. H., 1911. The Origin of Five Mutations in Eye-color in Drosophila. Science, XXXIII.
Morgan, T. H., 1912. The Ehmination of the Sex-chromosomes from the Male-producing Eggs of Phylloxerans. Jour. Exp. Zool, XII.
Morgan, T. H., 1912. Heredity of Body Color in Drosophila. Jour. Exp. Zool., XIII.
Morgan, T. H., 1912. A Modification of the Sex-ratio, and of other Ratios in Drosophila through Linkage. Zeits. Abst. Vererb., VII.
Morgan, T. H., 1912. Is the change in Sex-ratio of the Frog that is affected by External Agents, due to Partial Fertilization ? Am. Nat., XLVI.
Morgan, T. H., 1912. The Explanation of a New Sex Ratio in Drosophila. Science, XXXVI.
Morgan, T. H., 1912. Complete Linkage in* the Second Chromosome of the Male. Science, XXVI.
Morgan, T. H., 1912. Further Experiments with Mutations in Eye-color in Drosophila. Jour. Acad. Nat. Sci. Phil., XV.
Morgan, T. H., 1912. Eight Factors that show Sex-hnked Inheritance in Drosophila. Science, XXXV.
Morgan, T. H., 1912. The Masking of a Mendehan Result by the Influence of the Environment. Proc. Soc. E.vp. Biol. Med., IX.
Morgan, T. H., 1913. Factors and Unit Characters in Mendehan Heredity. Am. Nat., XLVII.
Morgan, T. H., and E. Cattell, 1912. Data for the Study of Sexlinked Inheritance in Drosophila. Jour. Exp. Zool., XIII.
Morgan, T. H., and E. Cattell, 1913. Additional Data for the Study of Sex-linked Inheritance in Drosophila. Jour. Exp. Zool, XIV.
Morgan, T. H., and H. D. Goodale, 1912. Sex-linked Inheritance
in Poultry. Ann. N. Y. Acad. Sci., XXII. Morgan, T. H., and C. J. Lynch, 1912. The Linkage of Two
Factors in Drosophila that are -not Sex-linked. Biol. Bull,
XXIII. Morgan, T. H., F. Payne, and E. N. Browne, 1910. A Method
to test the Hypothesis of Selective Fertilization. Biol. Bull.,
Morrill, C. V., 1909. Preliminary note on the Chromosomes in the Oogenesis, Fertihzation and Cleavage of certain Hemiptera. Science, XXX.
Morrill, C. V., 1910. The Chromosomes in the Oogenesis, Fertilization and Cleavage of Coreid Hemiptera. Biol. Bull, XIX.
Morse, M., 1910. Sterility. Am. Nat., XLIV.
MuLSOw, K., 1912. Der Chromosomencyclus bei Ancyracanthus cystidicola Rud. Arch. f. Zellf.. IX. 1.
Nachtsheim, H., 1912. Parthenogenese, Eireifung und Geschlechtsbestimmung bei der Honigbiene. Sitzungsber. Gesell Morph. u. Phys. Miinchen.
Newman, H. H., 1907. Spawning Behavior and Sexual Dimorphism in Fundulus heteroclitus and Alhed Fish. Biol. Bull., XII.
Newman, H. H., 1908. A Significant Case of Hermaphroditism in Fish. Biol. Bull, XV.
Newman, H. H., and J. T. Patterson, 1909. A Case of Normal Identical Quadruplets in the Nine-banded Armadillo. Biol.
Newman, H. H., and J. T. Patterson, 1910. The Development of the Nine-banded Armadillo, etc. Jour. Morph., XXI.
Newman, H. H., and J. T. Patterson, 1911. The Limits of Heredity Control in Armadillo Quadruplets. Jour. Morph., XXII.
Nussbaum, M., 1909. Uber Geschlechtsbildung bei Polypen. Arch. Gesell Physiol, CXXX.
Nuttall, G. H., and G. Merriam, 1911. The Process of Copulation in Ornithodorus moubata. Parasitology, IV.
Payne, F., 1912. A Further Study of the Chromosomes of the Redmdidae, etc. Jour. Morph., XXXIII.
Payne, F., 1912. The Chromosomes of Gryllotalpa boreahs. Arch. f. Zellf., IX.
Pearl, M. and R., 1908. On the Relation of Race Crossing to the
Sex Ratio. Biol. Bull, XV. Pearl, R., 1911. Inheritance of Fecundity in the Domestic Fowl.
Am. Nat., XLV. Pearl, R., 1911. Breeding Poultry for Egg Production. A7m.
Rep. Me. Agr. Exp. St., 1911. Pearl, R., 1912. The Mode of Inheritance of Fecundity in the
Domestic Fowl. Jour. E.vp. ZooL, XIII. Pearl, R., 1912. Notes on the History of Barred Breeds of
Poultry. Biol. Bull., XXII. Pearl, R., 1912. The Mendelian Inheritance of Fecundity in the
Domestic Fowl. Am. Nat., XLVI. Pearl, R., and M. R. Curtis, 1912. Studies on the Physiology of
Reproduction in the Domestic Fowl. Y. Jour. Exp. ZooL,
XIII. Pearl, R., and H. M. Parshley, 1913. Data on Sex Determination
in Cattle. Biol. Bull, XXIV. Pearl, R., and F. M. Surface, 1910. On the Inheritance of the
Barred Color Pattern in Poultry. Arch. Entw.-mech., XXX. Pearl, R., and F. M. Surface, 1910. Studies on Hybrid Poultry.
Papers Biol. Lab. Me. Agr. Exp. Sta., 21. Pearl, R., and F. M. Surface, 1910. Experiments in Breeding
Sweet Corn. Papers Biol. Lab. Me. Agr. E.vp. Sta., 18. Pearl, R., and F. M. Surface, 1910. Further Data Regarding the
Sex-limited Inheritance of the Barred Color Pattern in Poultry.
Science, XXXII. Pearl, R., and F. M. Surface, 1911. A Biometrical Study of Egg
Production in the Domestic Fowl. U. S. Dept. Agric, Bur.
Anim. hid., Bull. 110. Pearse, a. S., 1909. Observations on Copulation among Crawfishes with Special Reference to Sex Recognition. A7n. Nat.,
XLIII. Peckham, G. W. and E. G., 1889. Observations on Sexual Selection
in Spiders of the family Attida?. Nat. Hist. Soc. Wis. Occasional Papers, I. Peckham, G. W. and E. G., 1890. Additional Observations, with
some Remarks on Mr. Wallace's Theory of Sexual Ornamentation. Nat. Hist. Soc. Wis. Occasional Papers, I.
Pergande, T., 1904. North American Phylloxerinae affecting
Hicoria and other Trees. Proc. Dav. Acad. Sci., IX. Petrunkewitsch, a., 1902. Das Schicksal der Richtungskorper
im Drohnenei. Jena, 1902. Petrunkewitsch, A., 1910. Courtship in Dysdera crocata. Biol.
Bull, XIX. Phillips, E. F., 1903. A Review of Parthenogenesis. Proc. Am.
Phil. Soc, XLII. Plate, L., 1910. Die Erbformeln der Aglia tau-Rassen im Anschluss an die Standfusschen Ziichtungen. Arch. Rass. GeselL,
VII. Plate, L., 1913. Vererbungslehre. Leipzig. PococK, R. I., 1905. The Effects of Castration on the Horns of
a Prong Buck. Proc. Zool. Soc. Lond., I. Porter, J. P., 1906. The Habits, Instincts, and Mental Powers of
Spiders, Genera Argiope and Epeira. Am. Jour. Psych., XVII. Potts, F. A., 1910. Notes on Free-Living Nematodes. I.
Q. J. M. S., LV. PuNNETT, R. C, 1903. On Nutrition and Sex-determination in
Man. Proc. Cambr. Phil. Soc, XII. PuNNETT, R. C, 1906. Sex-determination in Hydatina, with
some Remarks on Parthenogenesis. Proc. Roy. Soc, LXXVIII. PuNNETT, R. C, 1909. On the Alleged Influence of Lecithin upon
the Determination of Sex in Rabbits. Proc. Camh. Phil. Soc,
XV. PuNNETT, R. C, 1910. Mimicry" in Ceylon Butterflies, etc.
Svol. Zeyl, VII. PuNNETT, R. C, 1911. MendeUsm. PuNNETT, R. C, 1912. Inheritance of Coat Color in Rabbits.
Jour. Genet., II. Rawls, E., 1913. Sex-ratios in Drosophila ampelophila. Biol.
Bull., XXIV. Regen, J., 1909. Kastration und ihre Folgeerscheinungen bei
Gryllus campestris. I. Zool. A)iz., XXXIV. Regen, J., 1910. Kastration und ihre Folgeerscheinungen bei
Gryllus campestris. II. Zool. Ariz., XXXV. Riddle, 0., 1909. Our Knowledge of Melanin Color Formation
and its Bearing on the Mendehan Description of Heredity.
Biol. Bull, XVI.
Riddle, 0., 1912. Preliminary Chemical Studies on Male and Female Producing Eggs of Pigeons. Science, XXXV.
Riddle, 0., and A. A. Spohn, 1912. On a Relation found to exist between Changes in the Chemical Composition of a Membrane and Changes in its Permeability. Science, XXXV.
Saunders, E. R., 1911. Further Experiments on the Inheritance of "Doubleness" and Other Characters in Stocks. Jour. Genet., I,
Saunders, E. R., 1911. Studies in the Inheritance of Doubleness in Flowers. I. Petunia. Jour. Genet., I.
ScHLEip, W., 1911. Variation, Hereditat, Bastardierung, Descendenzlehre. Jahrb. u. d. For. d. Anat. u. Entwtschr. Gesch., XVI.
ScHLEiP, W., 1912. Geschlechtsbestimmende Ursachen im Tierreich. Ergeb. und Fortschr. der ZooL, III.
ScHULTZE, 0., 1902. Was lehren uns Beobachtung und Experiment liber die Ursachen mannlichen und weiblicher Geschlechtsbildung, etc. ? Sitz.-ber. der Phys.-med. Gesell. Wilrzburg:
ScHULTZE, 0., 1903. Zur Frage von den geschlechtsbildenden Ursachen. Arch. mikr. Anat., LXIII.
Seiler, J., 1913. Das Verhaltung der Geschlechtschromosomen bei Lepidopteren. Zool. Anz.,XIA.
Seligmann, C. G., 1906. Proc. Zool. Soc. Loud., II., p. 903.
Shearer, C, 1911. The Problem of Sex-Determination in Dinophilus gj^'ociliatus. Jour. Marine Biol. Ass., IX.
Shearer, C, 1912. The Problem of Sex-Determination in Dinopliilus gyrociliatus. Q. J. M. S., LVII.
Shearer, C, and D. J. Lloyd, 1913. On Methods of Producing Artificial Parthenogenesis in Echinus esculentus, etc. Q. J. M. S., LVIII.
Shearer, C, W. de Morgan, andv H. M. Fuchs, 1911. Preliminary Notice on the Experimental Hybridization of Echinoids. Jour. Marine Biol. Ass., IX.
Shearer, C, W. de Morgan, and H. M. Fuchs, 1912. On Paternal Characters in Echinoid Hybrids. Q. J. M. S., LVIII.
Shull, a. F., 1910. Studies in the Life Cycle of Hydatina senta. Jour. Exp. Zool., VIII.
Shull, A. F., 1910. The Artificial Production of the Partheno
genetic and Sexual Phases of the Life Cycle of Hydatina senta. Am. Nat., XLIV. Shull, a. F., 19 1L Studies in the Life Cycle of Hydatina senta.
II. Jour. Exp. ZooL, X.
Shull, A. F., 1912. Studies in the Life Cycle of Hj^datina senta.
III. Jour. Exp. Zool, XII.
Shull, A. F., 1912. The Influence of Inbreeding on Vigor in Hydatina senta. Biol. Bull., XXIV. Shull, G. H., 1908. The Composition of a Field of Maize. Am.
Breeders^ Assoc, IV. Shull, G. H., 1909. The Presence and Absence" Hypothesis.
Am. Nat, XLIII. Shull, G. H., 1909. A Pure Line Method in Corn Breeding.
Am. Breed. Ass., V. Shull, G. H., 1910. Hybridization Methods in Corn Breeding.
Am. Breeders' Mag., I. Shull, G. H., 1910. Inheritance of Sex in Lychnis. Bot. Gaz.,
XLIX. Shull, G. H., 1911. Reversible Sex-mutants in Lychnis dioica.
Bot. Gaz., LII. Shull, G. H., 1912. Genotypes," " Biotypes," "Pure Lines," and
"Clones." fee/ice, XXXV. Shull, G. H., 1912. Hermaphrodite Females in Lychnis dioica.
Science, XXXVI. Smith, G., 1910. Studies in the Experimental Analysis of Sex.
Parts 1 and 2. Q. J. M. S., LIV. Smith, G., 1910. Studies in the Experimental Analysis of Sex.
Parts 3 and 4. Q. J. M. S., LV. Smith, G., 1911. Studies in the Experimental Analysis of Sex.
Part 5. Q. J. M. S., LVI. Smith, G., 1911. Studies in the Experimental Analysis of Sex.
Parte. Q. J. M.S., LYII. Smith, G., 1911. Studies in the Experimental Analysis of Sex.
Part 7. Q. J. M. S., LVII. Spemann, H., 1895. Zur Entwicklung des Strongylus paradoxus.
Zool. Jahrb. Anat. Abt., VIII. Spillman, W. J., 1908. Spurious Allelomorphism. Results of
Recent Investigations. Am. Nat., XLII.
Spillman, W. J., 1909. Barring in Barred Plymouth Rocks.
Poultry, V. Standfuss, M., 1896. Handbuch der palaarktischen Grosschmet terlinge. Jena. Standfuss, M., 1910. Chaerocampa elpenor und einige Mittei lungen iiber Aglia tau. Iris, XXIV. Staples-Browne, R., 1912. Second Report on the Inheritance of
Colour in Pigeons, with Special Reference to Sex-limited Inheritance. Jour. Genet., II. Steinach, E., 1912. Willkiirliche Umwandlung von Saugetier mannchen, etc. Arch. Gesell. Physiol., CXLIV. Stevens, N. M., 1905. Studies in Spermatogenesis with Especial
Reference to the '^Accessory Chromosome." Carnegie Inst.
Wash., pub. 36. Stevens, N. M., 1906. Studies in Spermatogenesis. II. Carnegie
Inst. Wash., pub. 36. Stevens, N. M., 1907. Color Inheritance and Sex Inheritance
in Certain Aphids. Science, XXVI. Stevens, N. M., 1908. The Chromosomes in Diabrotica, etc.
Jour. Exp. ZooL, V. Stevens, N. M., 1908. A Study of the Germ-cells of Certain
Diptera. Jo^ir. Exp. ZooL, V. Stevens, N. M., 1909. Further Studies on the Chromosomes of
the Coleoptera. Jour. Exp. ZooL, VI. Stevens, N. M., 1909. An Unpaired Chromosome in the Aphids.
Jour. Exp. ZooL, VI. Stevens, N. M., 1910. A Note on Reduction in the Maturation of
Male Eggs in Aphis. BioL BulL, XVIII. Stevens, N. M., 1910. The Chromosomes in the Germ-cells of
Culex. Jour. Exp. ZooL, VIII. Stevens, N. M., 1910. An Unequal Pair of Heterochromosomes
in Forficula. Jour. Exp. ZooL, VIII. Stevens, N. M., 1911. Further Studies on Heterochromosomes in
Mosquitoes. BioL Bull., XX. Stevens, N. M., 1911. Preliminary Note on Heterochromosomes
in the Guinea Pig. Biol. Bull., XX. Stevens, N. M., 1911. Heterochromosomes in the Guinea Pig.
BioL BulL, XXI.
Stockard, C. R., 1908. Habits, Reactions and Mating Instincts of the Walking Stick," Aplopus mayeri. Payers Tortugas Lab., II.
Strasburger, E., 1910. Ueber geschlechtbestimmende Ursachen. Jahrb. wiss. Bot., XL VIII.
Strong, R. M., 1912. Another View of Sex-hmited Inheritance. Science, XXXVI.
Strong, R. M., 1912. Results of Hybridizing Ring-Doves, Including Sex-Linked Inheritance. Biol. Bull., XXIII.
Sturtevant, a. H., 1911. Another Sex-limited Character in Fowls. Science, XXXIII.
Sturtevant, A. H., 1912. An Experiment Dealing with Sexlinkage in Fowls. Jour. E.xp. Zool., XII.
Sturtevant, A. H., 1912. Is there Association between the Yellow and Agouti Factors in Mice ? Ain. Nat., XLVI.
Sturtevant, A. H., 1912. Federley's Breeding Experiments with the Moth Pygsera. Am. Nat., XLVI.
Sturtevant, A. H., 1913. The Linear Arrangement of Six Sexlinked Factors in Drosophila, as shown by their Mode of Association. Jour. Exp. Zool., XIV.
Surface, F. M., 1912. The Diagnosis of Infectious Abortion in Cattle. Ann. Rep. Kent. Agr. Exp. Sta.
Sutton, W. S., 1902. On the Morphology, of the Chromosome Group in Brachystola magna. Biol. Bull., IV.
Sutton, W. S., 1903. The Chromosomes in Heredity. Biol. Bull., IV.
Tannreuther, W. S., 1907. History of the Germ-cells and Early Embryology of Certain Aphids. Zool. Jahrb. Anat. Abt., XXIV.
Tennent, D. H., 1911. A Heterochromosome of Male Origin in Echinoids. Biol. Bull., XXI.
Tennent, D. H., 1912. Studies in Cytology, I and II. Jour. Exp. Zool, XII.
Thomsen, E., 1911. Die Differenzierung des Geschlechts und das Verhaltnis der Geschlechter beim Htihnchen. Arch. Entw.mech. der Org., XXXI.
Tower, W. L., 1906. An Investigation of Evolution in Chrysomelid Beetles of the Genus Leptinotarsa. Carnegie Inst. Wash., pub. 48.
ToYAMA, K., 1907. Studies on Hybriclolog}^ of Insects. I. Bull.
Col. Agr. Tokyo Imp. Uni., VII. ToYAMA, K., 1912. On Certain Characteristics of the Silkworm
apparently Non-mendelian. Biol. Cent., XXXII. Tretjakoff, D., 1905. Die Spermatogenese bei Ascaris megalo cephala. Arch. mikr. Anat., LXV. Trow, A. H., 1913. On the Inheritance of Certain Characters in
the Common Groundsel — Senecio vulgaris — and its Segregates. Jour. Genet., II. Trow, A. H., 1913. Forms of Reduphcation — Primary and
Secondary. Jour. Genet., II. V. TscHERMAK, A., 1912. Ucber Veranderung der Form, Farbe
und Zeichnung von Kanarieneiern durch Bastardierung.
Arch. f. Gesell. Phjs., CXLVIII. V. TscHERMAK, E., 1908. Dcr moderne Stand des Vererbungs problems. Arch. Rass. und Gesell., V. DE ViLMORiN, P., and W. Bateson, 1911. A Case of Gametic
Coupling in Pisum. Proc. Roy. Soc, B, LXXXIV. DE Vries, H., 1901. Die Mutationstheorie. Leipzig. DE Vries, H., 1908. tJber die Zwillingsbastarde von (Enothera
nanella. Ber. deutsch. Bot. Gesell., XXVI a. DE Vries, H., 1908. Bastarde von (Enothera gigas. Ber. deutsch.
Bot. Gesell, XXVI a. DE Vries, Hugo, 1909. On Triple Hybrids. Bot. Gaz., XLIX. DE Vries, H., 1911. Uber doppeltreziproke Bastarde von (Enothera biennis und O. muricata. Biol. Centr., XXXI. Walker, C. E., 1908. The Influence of the Testis upon the
Secondary Sexual Characters of Fowls. Proc. Roy. Soc. Med.,
1908. Wenke, K., 1906. Anatomic eines Argynnis paphia — Zwitters.
Zeits. f. wiss. Zool, LXXXIV. Wheeler, W. M., 1903. The Origin of Female and Worker
Ants from the Eggs of Parthenogenetic Workers. Science,
XVIII. Wheeler, W. M., 1910. The Effects of Parasiric and other Kinds
of Castration in Insects. Jour. Exp. Zool., VIII. Wheeler, W. M., 1910. A Gynandromorphous Mutillid. Psyche,
Whitney, D. D., 1912. Rein\'igoration produced by Cross Fertilization in Hydatina senta. Jour. Exp. Zool., XII. Wilder, H. H., 1904. Duplicate Twins and Double Monsters.
Ajn. Jour. Anat., III. Williams, L. W., 1907. The Significance of the Grasping Antennae
of the Harpactecoid Copepods. Science, XXV. Wilson, E. B., 1899. The Cell in Development and Inheritance.
New York. Wilson, E. B., 1905. Studies on Chromosomes, I and II. Jour.
Exp. Zool, II. Wilson, E. B., 1906. Studies on Chromosomes, III. Jour. Exp.
Zool, III. Wilson, E. B., 1909. Studies on Chromosomes, IV and V. Jour.
Exp. Zool, VI. Wilson, E. B., 1909. Recent Researches on the Determination and
Inheritance of Sex. Science, XXIX. Wilson, E. B., 1909. Secondary Chromosome Couphngs and the
Sexual Relations in Abraxas. Science, XXIX. Wilson, E. B., 1910. Note on the Chromosomes of Nezara.
Science, XXXI. Wilson, E. B., 1910. The Chromosomes in Relation to the Determination of Sex. Sci. Progr., XVI. Wilson, E. B., 1910. Studies on Chromosomes, VI. Jour. Exp.
Zool, IX. Wilson, E. B., 1911. Studies on Chromosomes, VII. Jour.
Morph., XXII. Wilson, E. B., 1911. The Sex Chromosomes. Arch. Mikr. Anal,
LXXVII. Wilson, E. B., 1912. Studies on Chromosomes, VIII. Jour.
Exp. Zool, XIII. Wilson, E. B., 1912. Some Aspects of Cytology in Relation to the
Study of Genetics. Am. Nal, XLVI. WoLTERECK, R., 1911. Ubcr Veranderung der Sexuahtat bei
Daphniden. Leipzig, 1911. Wood, J. G., 1874. Insects Abroad. New York. Woodruff, L. L., 1905. An Experimental Study of the
Life-History of Hypotrichous Infusoria. Jour. Exp. Zool,
Woodruff, L. L., 190S. The Life Cycle of Paramecium Proc.
Soc. Exp. Biol, and Med., 1908. Woodruff, L. L., 1908. The Life Cycle of Paramecium when
subjected to a Varied Environment. Amer. Nat., XLII. Woodruff, L. L., 1908. Effects of Alcohol on the Life Cycle
of Infusoria. Biol. Bull., XV. Woodruff, L. L., 1912. A Summary of the Results of Certain
Physiological Studies on a Pedigreed Race of Paramecium.
Bioch. Bidl., I. Woodruff, L. L., 1912, Observations on the Origin and Sequence
of the Protozoan Fauna of Hay Infusions. Jour. Exp. ZooL,
XII. Woodruff, L. L., and G. A. Baitsell, 1911. Rhythms in the
Reproductive Activity of Infusoria. Jour. Exp. ZooL, II. Zacharias, 0., 1912. Zur Cytologic des Eies von Ascaris megalo cephala. Anat. Anz., XLII. ZiEGLER, H. E., 1911. Die Chromosomen als Vererbungstrager.
Jahresb. d. Vereins. vaterl. Naturk. Wurzburg, LXVII.
Abraxas, 128 Achates, 151 Achia, 106
Addison's disease, 147 Adkins, 217-218 Adrenal, 147 Agenor, 151 Allen, 113 Amphibia, 145 Amphipoda, 117 Andrews, 117 Angiostomum, 170 Antlers, 110, 133 Ants, 117 Argentine, 227 Argonauta, 26 Aristotle, 35 Armadillo, 238 Ascaris, 20, 21, 49 Ascidian, 217
Baltzer, 55, 58, 61
Bateson, 72, 75, 99, 100, 125
Baur, E., 99
Bee, 174, 175, 176, 220
Bird of paradise, king, 109
superb, 109 Black, 96-97 Blakeslee, 171 Bobolink, 27 Boring, 51 Boveri, 51, 55, 58, 162, 165, 170,
171 Bresca, 145 Bridges, 223, 224
Bruce, 212 Bryonia, 171-172 Biitschli, 8
Calkins, 8, 198, 206, 209, 210
Capons, 142, 143
Ceylon, 125, 127
Checker diagram, 78
Clipped wings, 119
Colias, 129-130, 150
Color blindness, 242
Conger eel, 2
Corpus luteum, 147
Correns, 74, 79, 99, 171, 172. 215. 216
Cuenot, 232, 233
Daphnians, 182-185, 189
Darwin, C, 73-74, 101, 103, 104, 107,
112-414, 120, 125, 142, 194, 197,
200-202 Davenport, C, 72, 143, 239 Deer, 110, 133, 134 Delage, 193 Dinophilus, 234 Diplogaster, 225 Doncaster, 176
Dorsets, 134, 135, 136, 137, 138 Drelincourt, 232 Drone, 175
Drosophila, 63-68, 96, 117, 130 Dusing, 233
East, 99, 202, 204, 211 Edwards, 51 Egret, 111 Eland, 136 Elaphomyia, 106 Elephant, 110 Emerson, 99 Eosin eye, 130, 154, 155 Eupaguras, 158 Euschistus, 151
Fabre, 220, 221
Firefly, 28, 30, 31
Frog, 145, 147, 228
Fruit fly, 117, 195, 196, 221
Gall, 179 Galton, 236 Game, 144, 212 Geddes, 232 Gentry, 232 Germ-cells, 23 Gerould, 130, 150, 151 Giard, 155 Gigantism, 146 Goldschmidt, 124 Goodale, 72, 142 Gosse, 103 Growth, 3 Gudernatsch, 147 Guinea hen, 225 Gulick, 51
Guyer, 225-226, 245 Gynandromorphism, 161 Gypsy moths, 117
Habrocestum, 107 Hsemophilia, 239, 240, 242 Hectoeotylized arm, 26 Honking, 50 Herbst, 55, 61, 62 Herdwicks, 134-135
Hermaphroditism, 161 Hertwig, R., 9, 228, 234 Holmes, 117 Hormones, 146 Horns, 133-138 Hudson, 114, 115 Humming-birds, 103, 108 Hydatina, 2, 185 Hyde, 196, 199, 215
Ichthyosis, 242 Identical twins, 236-239 Inachus, 155 Ipomoea, 197 Italian, 227
.Jennings, 9, 12, 206-208
Jordan, H. E., 245
Keeble, 212 Kellogg, 117, 232 King, 229, 234 Kopec, 149 Kruger, 225 Kuschakewitsch, 228
Lamarckian school, 17
Lethal factor, 221-223
Loeb, J., 62, 190, 191, 192, 193
Mallard, 28, 142
Malsen, von, 234, 235, 236
Mammary glands, 140
Man, 34, 229, 236-249
Maupas, 5, 8, 187, 198, 234
de Meijere, 151
Meisenheimer, 145, 148-149
Mendel, 84, 73-75, 80, 84
Merino, 134, 135
Miastor, 21, 174
Miniature wings, 66-67
Montgomery, 34, 50, 115, 117, 245
Nematode, 224-226 Nereis, 36
Neuroterus, 176-177 Nswmann, 238 Night blindness, 242 Non-disjunction, 223-224 Nussbaum, 16, 145
Ocneria, 148 Octopus, 25 Oncopeltus, 46, 84 Optic nerve atrophy, 244 Oudemans, 148 Ovariotomy, 135 Owl, 111
Papilio, 125-129, 151
Paramoecium, 5, 6, 12, 206-211
Pea, edible, 75-78, 85-88
Pearl, R., 72, 212-213, 227
Peckham, 115-116, 120
Phylloxerans, 52, 54, 178, 179, 180,
181, 189 Pigeons, 32 Pituitary body, 146 Plutei, 60
Plymouth rock, 69-71, 212 Polar bodies, 37 Polytmus, 103 Porter, 117 Porthetria, 117, 148 Primula, 201, 202 Promethea, 116 Protenor, 40 Punnett, 127, 128, 138, 233
Rawls, 221 Rat, 140, 233 Reduplication, 100 Reindeer, 136 Rhabditis, 169, 224, 226 Riley, 232 Ritzema-Bos, 195 Rotifers, 185-189 Rudimentary wing, 214, 215 Russo, 234
Sagitta, 21, 22
Schleip, 170, 171
Sea cow, 27
Sea-lion, Steller's, 110
Segregation, 81, 100
Sex, 83, 84
Sex chromosome, 50, 80, 83, 84
Sex determination, 84
Sex-linked, 81, 83, 84, 132
Shull, A. F., 187, 197, 205
Shull, G. H., 173, 202, 204, 211
Siamese twins, 236
Silkworm, 117, 165
Skeleton, rat, 140 Smith, G., 145, 155 Soule, 116 Sparrow, 2 Spermatophores, 25 Sphsereohinus, 59-60 Spiders, 34, 107, 115, 117 Squid, 24 Stag, 133 Steinach, 140 Stephanosphaera, 5 Stevens, 51 Strobell, 151
Strongylocentrotus, 59, 60, 62 Sturtevant, 72, 98, 117, 118 Stylonichia, 2 Suffolks, 136-138 Synapsis, 93
Tadpoles, 147 Tanager, scarlet, 27 Thomson, 232 Thymus, 146-147 Thyroid, 146-147 Toad, 229 Tower, 117 Toyama, 165 Treat, 232
Triton, 145 Trow, 99 Tschermak, 74
Vermilion eye, 119 Vestigial wing, 96-97 Vigor, 120 Vincent, 146 de Vries, 74, 125
Wallace, 102, 113-114, 120, 125, 127
Weismann, 16, 17, 40, 194, 195
White eye, 62-65, 81, 82, 88-92, 118,
119, 221-223 Whitney, 185, 187, 197, 205 Wilder, 237 Wilson, 51 Winiwarter, 245-248 Wood, 136 Woodruff, 8, 198
X-chromosome, 51, 82, 84, 242
Y-chromosome, 51, 84
Yellow body color, 67, 88-92, 119