v COLOURS OF ANIMALS 371 



fight and struggle for the almost passive female, and that the 

 most vigorous and energetic, the strongestxwlnged or the most 

 persevering, wins her. How can there be chance in this ? 

 Natural selection would here act, as in birds, in perpetuating 

 the strongest and most vigorous males ; and as these would 

 usually be the more highly coloured of their race, the same 

 results would be produced as regards the intensification and 

 variation of colour in the one case as in the other. 



Let us now see how these principles will apply to some of 

 the cases adduced by Mr. Darwin in support of his theory of 

 conscious sexual selection. 



In Descent of Man, 2d ed., pp. 307-316, we find an elaborate 

 account of the various modes of colouring of butterflies and 

 moths, proving that the coloured parts are always more or 

 less displayed, and that they have some evident relation to 

 an observer. Mr. Darwin then says : " From the several 

 foregoing facts it is impossible to admit that the brilliant 

 colours of butterflies, and of some few moths, have commonly 

 been acquired for the sake of protection. We have seen that 

 their colours and elegant patterns are arranged and exhibited 

 as if for display. Hence I am led to believe that the females 

 prefer or are most excited by the more brilliant males ; for on 

 any other supposition the males would, as far as we can see, 

 be ornamented to no purpose" (I.e. p. 316). I am not aware 

 that any one has ever maintained that the brilliant colours of 

 butterflies have " commonly been acquired for the sake of 

 protection," yet Mr. Darwin has himself referred to cases in 

 which the brilliant colour is so placed as to serve for protec- 

 tion; as, for example, the eye- spots on the hind wings of 

 moths, which are pierced by birds and so save the vital parts 

 of the insect, while the bright patch on the orange-tip butter- 

 flies, which Mr. Darwin denies are protective, may serve the 

 same purpose. It is, in fact, somewhat remarkable how very 

 generally the black spots, ocelli, or bright patches of colour 

 are on the tips, margins, or discs of the wings ; and as the 

 insects are necessarily visible while flying, and this is the 

 time when they are most subject to attacks by insectivorous 

 birds, the position of the more conspicuous parts at some 

 distance from the body may be a real protection to them. 

 Again, Mr. Darwin admits that the white colour of the male 



