284 THE COLOUES OF ANIMALS 



CHAPTER XV 



COLOURS PRODUCED BY COURTSHIP 



IN addition to the colours and patterns which assist 

 an animal to evade or warn off its enemies or to secure 

 its prey, there are also colours arid appendages which 

 must have some very different meaning. These ap- 

 pearances are seen in mature animals, and frequently 

 undergo periodical development at times which cor- 

 respond to the breeding season; and when the two 

 sexes differ, the males are almost invariably the more 

 brilliant. Although far less important and wide-spread 

 than the protective or aggressive colours, they are 

 more generally known and appreciated, because they 

 are conspicuous as well as beautiful, and are freely 

 displayed by the animals which possess them. 



The theory of Sexual Selection 



However these colours may have arisen, every ob- 

 server must admit that they are in some way connected 

 with sex. Darwin accounted for them by his celebrated 

 theory of * Sexual Selection.' ' He supposed that 



1 The Descent of Man, Part ii. Sexual Selection. 



