SELECTION 465 



Selection " 'which is in a way " a blend between Sexual and 

 Natural Selection ". 



(i) A survey of recent observations on mating, as in Mr. 

 W. P. Pycraft's Courtship of Animals (1913), leaves an 

 impression of an intricacy and subtlety that baffles descrip- 

 tion. We agree with this distinguished expert as to the 

 need for psychological as well as physiological interpre- 

 tation. It is probable that no naturalist has studied a court- 

 ship with the thoroughness that Mr. Huxley shows in his 

 account of the Great Crested Grebe, and what is his verdict ? 

 " Display and ornament do not act on the aesthetic sense 

 of the female, but on her emotional state; they are using 

 the words in no narrow or unpleasant sense excitants, 

 aphrodisiacs, serving to raise the female into that state of 

 exaltation and emotion when alone she will be ready to pair. 

 . . . But the element of choice does, in another form, 

 remain. In animals such as Birds, where there is a regular 

 pairing-up season, and where, too, the mental processes are 

 already of considerable complexity, it is impossible to doubt 

 but that mating may be, and in some species is, guided by 

 impulse, unanalysable fancies, individual predilection." 



(/') In his Studies in Animal Behaviour (1916) Mr. S. J. 

 Holmes has an interesting chapter on " the role of sex in 

 the evolution of mind ". Let us take one illustration. " The 

 primary function of the vocal apparatus of the Vertebrates 

 was probably to furnish a sex call, as is now its exclusive 

 function in the Amphibia. Only later and secondarily did 

 the voice come to be employed in protecting and fostering 

 the young, and as a means of social communication. And 

 the evolution of the voice in Vertebrates doubtless influenced 

 to a marked degree the evolution of the sense of hearing. 

 It is not improbable, therefore, that the evolution of the voice, 



