THE PLAY OF ANIMALS. 239 



able that condition may be for them, must be referred 

 at once to natural selection.* 



The case is quite different, as I have remarked, with 

 the first element of Wallace's theory. Here the gifted 

 author advances his original ideas and reaches conclu- 

 sions which are calculated, in my opinion, to seriously 

 modify the Darwinian theory of sexual selection. Tak- 

 ing, as an example, the parrot which is commonly of a 

 green ground colour with stripes of yellow, red, and 

 blue, Wallace would say that through adaptation to 

 life in the woods the green colour serves as a defence, 

 while the stripes are distinguishing marks for purposes 

 of recognition, and we have brilliant plumage explained 

 satisfactorily without any reference to sexual selection, 

 which can not, then, have the range that Darwin at- 

 tributes to it in accounting for the colouring and other 

 ornamentation of animals. 



Quite as convincing, too, is the argument against 

 the exercise of aesthetic judgment, comparison, and se- 

 lection in pairing. I am even inclined to go further 

 than Wallace and exclude the conscious choice of even 

 the strongest and bravest, which he seems disposed to 

 admit, but I do not on that account imagine that the 

 Darwinian hypothesis is refuted. 



Going on to consider bird-songs, Wallace says: 

 " The peculiar calls of birds, and even the singing of 

 the males, may very well have originated merely as a 



* [It is precisely at such critical junctures as this that the prin- 

 ciple of Organic Selection (see above, p. 64, and the Appendix) is 

 needed to relieve the strain on natural selection. If there be any 

 preferential mating — even the little conscious choice admitted by 

 Wallace, or the more physiological sort suggested by Groos — it 

 would set the direction in which natural selection would accumu- 

 late variations. — J. M. B.] 



