The Theory of Sexual Selection. 393 



one, unless, as Wallace supposes, there is some cor- 

 relation between embellishment and general perfection, 

 in which case, as he points out, the theory of sexual 

 selection lapses altogether, and becomes but a special 

 case of natural selection. 



Once more, Mr. Wallace argues that the evidence 

 collected by Mr. Darwin himself proves that each bird 

 finds a mate under any circumstances— a general fact 

 which in itself must quite neutralize any effect of 

 sexual selection of colour or ornament, since the less 

 highly coloured birds would be at no disadvantage as 

 regards the leaving of healthy progeny. 



Lastly, he urges the high improbability that through 

 thousands of generations all the females of any par- 

 ticular species — possibly spread over an enormous 

 area — should uniformly and always have displayed 

 exactly the same taste with respect to every detail of 

 colour to be presented by the males. 



Now, without any question, we have here a most 

 powerful array of objections against the theory of 

 sexual selection. Each of them is ably developed by 

 Mr. Wallace himself in his work on Tropical Nature ; 

 and although I have here space only to state them in 

 the most abbreviated of possible forms, I think it will 

 be apparent how formidable these objections appear. 

 Unfortunately the work in which they are mainly pre- 

 sented was published several years after the second 

 edition of the Descent of Man, so that Mr. Darwin 

 never had a suitable opportunity of replying. But, if 

 he had had such an opportunity, as far as I can judge 

 it seems that his reply would have been more or less 

 as follows. 



In the first place, Mr. Wallace fails to distinguish 



