AUTHOR S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, AUGUST 15 



STUDIES ON INBREEDING 



III. THE EFFECTS OF INBREEDING, WITH SELECTION, ON THE SEX 

 RATIO OF THE ALBINO RAT 



HELEN DEAN KING 



The Wistar Institute of Anatomy and Biology 



ONE FIGURE 



During the latter part of the nineteenth century it was gener- 

 ally believed that sex in man and in various animals is determined 

 mainly by the amount of nourishment 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 

 collected by Diising ('83, '84, '86), who maintained, furthennore, 

 that close inbreeding interferes with embryonic nutrition, by 

 lessening the vitality of the mother, and so produces a great 

 excess of male young. 



In the literature of the succeeding twenty years that deals 

 with the subject of sex determination, Diising' s statement regard- 

 ing the effect of inbreeding on the sex ratio was widely quoted 

 and generally credited. Those who challenged the truth of the 

 assertion were, in the main, advocates of the ancient theory, 

 generally ascribed to Hippocrates (460-377 B.C.), that sex is 

 determined in the ovary; eggs from the right ovary producing 

 males and those from the left ovary developing into females. 

 During this period three series of experiments were made that 

 give data regarding the sex-proportions in a closely inbred stock. 

 Huth ('87) inbred rabbits, brother and sister, for six generations 

 and found a relatively low sex ratio (78.8 cf : 100 9 ) among the 

 ninety young in which the sex was ascertained; Copeman and 

 Parsons ('04) obtained a similar result in their inbreeding experi- 

 ments with mice. Schultze ('03) concluded that inbreeding 



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THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 27, NO. 1 

 OCTOBER, 1918 



