Habits and Instincts of the Pairing Season. 219 



males of less exuberant vitality by direct combat. Such 

 competition, by which the weakest are excluded from 

 mating through no choice on the part of the female, falls 

 under the head of natural selection, and not of sexual 

 selection, if by that term we understand preferential 

 mating. 



This serves to bring out the difference, before adverted 

 to, between natural selection through elimination and 

 conscious selection through choice. The two processes 

 begin at different ends of the scale of efficiency. Natural 

 selection begins by eliminating the weakest, and so works 

 up the scale from its lower end until none but the fittest 

 survive ; there is no conscious choice in the matter. 

 Sexual selection by preferential mating begins by selecting 

 the most successful in stimulating the pairing instinct, 

 and so works down the scale until none but the hopelessly 

 unattractive remain unmated. The process is determined 

 by conscious choice. It is in and through such choice 

 that consciousness has been a factor in evolution. The 

 relations of the two processes will, however, be more fully 

 considered in a later chapter. 



It forms no part of my present purpose to discuss in 

 detail the theory of sexual selection. Only in so far as 

 the conceptions which it involves bear upon problems 

 of habit and instinct does the theory concern us here. 

 The song of birds is an instinctive or an habitual activity, 

 which appears to be the expression of an emotional state 

 coincident in time, in the majority of song-birds, with the 

 season of courtship. Emotional expression is, in other 

 cases, of suggestive value. It is, therefore, not improbable 

 that song arouses in the hen an answering emotional state ; 

 and it is said that hen-canaries mate with the best singer. 

 If the number of male birds is in excess of that necessary 

 to satisfy the pairing requirements of the hens (and this 



