HEEEDITY AND SEX 



develops only from a fertilized egg, neverthe- 

 less the male possesses fewer chromosomes than 



FIG. 50. Diagram of sex-determination when the female is 

 homozygous, the male heterozygous. 



the female. In such cases the female forms, 

 as in cases of parthenogenesis, only N gametes, 

 but the male forms gametes of two sorts, N and 



167 



