SEX INHERITANCE 127 



intersexuality appears. Externally the daughters 

 are ''almost indistinguishable from normal males." 

 The instincts are entirely male and the moths try 

 unsuccessfully to mate with females. The gonads 

 look like testes, but show in sections a mixture of 

 ovarian and testicular tissue. A step further and 

 the daughters w^ould be completely transformed into 

 males. The next cross gives this final stage. When 

 Jap. male is crossed to any race of European 

 female, only males are produced, i.e., all the 

 daughters become sons. 



The reverse picture is given by those combinations 

 in which the intersexes are sons partly changed 

 over into daughters, a condition that Goldschmidt 

 terms male intersexualit3^ The wings are generally 

 streaked with white and in the extremest type only 

 a few spots of the brown characteristic of the male 

 appear on the wing-veins. The testis may contain 

 some ovarian tissue, but the changes in the gonads 

 do not appear to run parallel to those seen on the 

 surface. 



The explanation that Goldschmidt offers for these 

 intersexes is entirely different from the explanation 

 that is demonstrated for tlie gjaiandromorj^hs of 

 Drosopkila. He accepts the chromosome theory of 

 sex determination, and applies it to the present 

 case on the basis that the female is heterozygous 

 for the sex chromosome Mm (ZW), and the male 

 hvmozygous MM (ZZ). In addition, however, 

 Goldschmidt adds another set of sex-determining 

 factors that he calls FF (inclosing them in brackets), 



