Vv COLOURS OF ANIMALS 371 
fight and struggle for the almost passive female, and that the 
most vigorous and energetic, the strongest-winged 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” (/.c. p. 316). Iam 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 
distanée from the body may be a real protection to them. 
Again, Mr. Darwin admits that the white colour of the male 
