THEORY OF EVOLUTION 63 



is yellow or white. The inheritance is, accord- 

 ing to Gerould, strictly Mendelian. 



In Papilio turnus there exist, in the southern 

 states, two kinds of females, one yellow like 

 the male, one black (fig. 27). The evidence 

 here is not so certain, but it seems probable that 



FIG. 27. Papilio turnus with two types of females above and 

 one type of male below. 



a single factor difference determines whether 

 the female shall be yellow or black. 



Finally in Papilio polytes of Ceylon and 

 India three different types of females appear, 



