256 



The Journal of Heredity 



autocracy, selfishness, which resuhs in 

 war, slaughter, disease, and the degener- 

 ation of mankind. 



There is also the esthetic argument 

 for democracy which I shall at present 

 refrain from expounding, as Mr. Ireland 

 would doubtless consider it a sort of 

 fourth-dimension vaporing. It is, not- 

 withstanding, responsible for the opin- 

 ions of a considerable portion of the 

 world's population. 



I repeat, however, that I offer these 

 opinions not as the opinions of an expert. 



but as the opinions of a layman. It is 

 only because I suspect that a great 

 many other laymen may hold them that 

 I trouble you with them. But this 

 being the case, I think it would be worth 

 while for your experts to set me and 

 my comrades in ignorance right on these 

 matters if we are wrong. For such, I 

 take it, is the social function of experts. 

 Very truly yours, 



A. Y. Winters. 

 St. Vincent Sanitarium, 

 Santa Fe, N. M. 



A FACTOR INFLUENCING 



THE SEX-RATIO 



DURING the latter part of the 

 nineteenth century it was gen- 

 erally beheved that sex in man 

 and in various animals is deter- 

 mined mainly by the amount of nour- 

 ishment that the embryos receive ; well- 

 nourished embryos were supposed to 

 become females ; those that were poorly 

 nourished were assumed to develop 

 into males. A considerable amount of 

 evidence in favor of this view was col- 

 lected by Diising ('83, '84, '86), who 

 maintained, furthermore, that close 

 inbreeding interferes with embryonic 

 nutrition, by lessening the vitality of the 

 mother, and so produces a great excess 

 of male young. 



Helen Dean King has recently re- 

 ported some results of the effect of 

 inbreeding upon the production of male 

 or female offspring among albino rats. 

 Her conclusions in part are as follows:^ 



In each series the difference between 

 the sex ratio for the group of inbred 

 litters and that for the group of half-in- 

 bred litters is a significant one. Appar- 

 ently, therefore, the chemotactic reac- 

 tion between the ovum and the sperma- 

 tozoon is not quite the same where these 

 sexual elements come from unrelated 

 individuals as when they are produced 

 bv individuals that are closely inbred. 



Morgan ('14) has suggested that 

 the infertility of the eggs of Ciona 

 to spermatozoa from the same individual 

 may be due to the similarity in the 

 hereditary complex of the germ cells, 

 which in some way decreases the chances 

 of their uniting. The selective fertiliza- 

 tion experiments made by Marshall 

 ('10) with different varieties of dogs and 

 also my own experiments with different 

 varieties of rats show that the ova of 

 these animals have a strong tendency 

 to unite with spermatozoa from in- 

 dividuals belonging to unrelated stock 

 rather than with spermatozoa from 

 individuals of the same blood. 



The results of this series of experi- 

 ments, as a whole, seem to indicate that 

 in the rat, as in the pigeon (Riddle, '14, 

 '16, '17), in Drosophila (Moenkhaus, 

 '11) and in the guinea-pig (Papanicolau, 

 '15), the female has more influence in 

 determining the sex ratio than has the 

 male. Yet it is not in the differentia- 

 tion of the ova, nor in the development 

 of the spermatozoa, that the key to 

 the riddle of sex-determination will be 

 found. A knowledge of the interaction 

 of the germ cells, and of the conditions 

 that influence it, must be gained before 

 the final solution of this problem can 

 be attained. 



» Helen Dean King. Studies on Inbreeding — III. The effects of inbreeding, with selection 

 on the sex ratio of the albino rat. Journal of Experimental Zoology, vol. 27, No. 1. 



