74 SEX 



ensemble most successfully excites her sexual 

 interest. In some passages Darwin seems to 

 credit the female with a high degree of taste 

 or aesthetic fastidiousness ; he was doubtless 

 on safer ground when he wrote, "it is not 

 probable that she consciously deliberates ; but 

 she is most excited or attracted by the most 

 beautiful, or melodious, or gall.'-nt males." 

 A useful suggestion has been made by Groos 

 that the displays of the excited suitors- 

 displays often more reflex than controlled 

 have the effect of infectiously exciting the 

 female and of overcoming her coyness, a 

 character which is of no inconsiderable racial 

 value. An easily excited, readily persuaded 

 female type would not make for racial stability. 



The difficulty that a particular quality of 

 the male could not be augmented by selection 

 without also affecting the corresponding char- 

 acter in the female progeny of successive 

 generations, will be discussed later, but we 

 may point out that although a quality passes 

 into the inheritance of both sexes, the con- 

 ditions of development may prevent it finding 

 expression except in one sex. 



Another difficulty is raised by the fact that 

 there are some cases of pronounced sex- 

 dimorphism where there is no evidence either 

 of preferential mating or of combats. Sub- 

 sidiary hypotheses have been invented to 

 meet these cases, such as Wallace's that 

 Natural Selection would tend to eliminate 

 females that were conspicuous during incu- 

 bation, or Giinther's that masculine char- 

 acters have their justification as a means of 

 " bluffing " enemies. 



