162 



HEREDITY AND SEX 



morphs have arisen, of which two examples are shown 

 in Fig. 82. In the first case the fly is female on one 

 side, as shown by the bands of her abdomen, and male 

 on the other side (upper right-hand drawing). 



In the second case the fly looked like a female seen 

 from above. But beneath, at the posterior end, the 

 genital organs of the male are present, and normal 



Fig. 81. 



A gynandromorph niutillid wasp, Pseudomethoca canadensis, 

 male on right side, female on left side. 



in structure. In the latter case the fly is ostensibly 

 a female, except for the male organs of reproduction. 



How can we interpret these cases ? We find a 

 clue, I think, in the bee. It is known that if the egg 

 of the bee is fertilized, it produces a female — only 

 female-producing sperms are formed. If it is un- 

 fertilized, it produces a male. In the bee two polar 

 bodies are produced, and after their extrusion the num- 

 ber of chromosomes is reduced to half, as in ordinary 

 cases. The haploid number produces a male ; the 

 double number produces a female. 



Boveri pointed out that if through any chance the 



