xxii THE PLAY OF ANIMALS. 



iication of the doctrine of sexual selection, making it a 

 special case of natural selection. While agreeing with 

 Wallace that the unusual colours and forms, as well as 

 complicated calls, are to be considered as largely a 

 means of defence and offence and of recognition among 

 animals, I yet believe that in their higher manifestations 

 such phenomena often have a very close connection 

 with sexual life. This is more obviously the case with 

 the display of ornamentation, of skill in flying, dan- 

 cing, and swimming, and in bird-song. The disciple of 

 Weismann who can not accept Spencer's explanation of 

 such phenomena must either cleave to Darwin's sexual 

 selection, as Weismann himself does, or seek a new 

 principle. Such a principle I believe I have found. It 

 depends on two closely related facts. As sexual impulse 

 must have tremendous power, it is for the interest of the 

 preservation of the species that its discharge should be 

 rendered difficult. This result is partly acomplished in 

 the animal world by the necessity for great and often 

 long-continued excitement as a prelude to the act of 

 pairing. This thought at once throws light on the 

 peculiar hereditary arts of courtship, especially on the 

 indulgence in flying, dancing, or singing by a whole 

 flock at once. But the hindrance to the sexual func- 

 tion that is most efficacious, though hitherto unappre- 

 ciated, is the instinctive coyness of the female. This 

 it is that necessitates all the arts of courtship, and 

 the probability is that seldom or never does the fe- 

 male exert any choice. She is not awarder of the prize, 

 but rather a hunted creature. So, just as the beast 

 of prey has special instincts for finding his prey, 

 the ardent male must have special instincts for sub- 

 duing feminine reluctance; and just as in the beast 

 of prey the instinct of ravenous pursuit is refined into 



