292 GENETICS 



Similarly a misplaced ^-chromosome in a primary 

 germ-cell may cause testes to form in a female. Such 

 a case of gynandromorphism in Thelia (Kornhauser) 

 proved upon actual chromosome count to have one 

 ^-chromosome missing. 



It is rather difficult to offer any simple mechanical 

 explanation for the mosaics or sex-intergrades of 

 moths and daphnids. Goldschmidt has attempted to 

 explain his results upon a quantitative basis, assign- 

 ing values for the determiners for maleness and female- 

 ness, and adding the assumption that the strength of 

 these determiners varies in different races. Thus, the 

 crossing of a strong male race with a weak male race 

 brings about an upset of normal conditions, establish- 

 ing a new balance of factors so that neither one sex nor 

 the other predominates. An expression of two sets of 

 genes, therefore, is brought about in various parts of 

 the organism. 



Bridges* recent work on triploid races of Drosophila 

 seems to indicate that when the normal relation of the 

 autosomal genes to the sex-genes of the ^-chromosome 

 is upset, either by the preponderance of one or the 

 other, then sex abnormalities of many sorts may be 

 expected. 



10. HEEMAPHEODITISM 



One of the most obscure problems of the entire sex 

 question is that of hermaphroditism, or the production 

 of ova and sperm by a single individual. Instances of 

 this condition are found normally occurring in many 

 groups of invertebrates, such as coelenterates, cteno- 



