150 



HEREDITY AND SEX 



that in these insects the essential organs of reproduc- 

 tion have no influence on the secondary sexual char- 

 acters of the individual. They show furthermore that 

 the male generative organs will develop as well in 

 the female as in the body of the male itself, and vice 

 versa. 



It is evident, then, in insects (there is a similar, but 

 less complete, series of experiments on the cricket). 



Fig. 76. — Papilio Memnon. 1, male; 2, 3, 4, three types of females. 



(After Meijere.) 



that the heredity of the secondary sexual characters 

 can be studied quite apart from the influence of the 

 sex glands. How, then, are they inherited so that they 

 appear in one sex and not in the other sex? Within 

 the last two or three years the inheritance of the second- 

 ary sexual differences in insects has been studied. 



First, there is the case of the clover butterfly, Colias 

 philodice, that Gerould has worked out, where there 



