“Mr. Darwin admits,” he continues, “that these bright colours have been acquired for protection [because they resemble those of species which from their disagreeable taste are avoided by birds and other insect-eating enemies]; but as there is no apparent cause for the strict limitation of the colour to the female, he believes that it has been kept down in the male by its being unattractive to her. This appears to me to be a supposition opposed to the whole theory of Sexual Selection itself. For this theory is, that minute variations of colour in the male are attractive to the female, have always been selected, and that thus the brilliant male colours have been produced. But in this case he thinks that the female Butterfly had a constant aversion to every trace of colour, even when we must suppose it was constantly recurring during the successive variations which resulted in such a marvellous change in herself. But the case admits of a much more simple interpretation. For if we consider the fact that the females frequent the forests where the Heliconidæ abound [the distasteful species already referred to] while the males fly much in the open and assemble in great numbers with other white and yellow Butterflies on the banks of rivers, may it not be possible that the appearance of orange-stripes or patches would be as injurious to the male as it was useful to the female, by making him a more easy mark for insectivorous birds among his white companions? This seems a more probable supposition than the altogether hypothetical choice of the female, sometimes exercised in favour of, and sometimes against, every new variety of colour in her partner.” Wallace’s arguments are not so crushing as he supposed them to be, and they contribute nothing towards the solution of the problem to be faced. But if colour played the part which Darwin believed, and colour alone be concerned, it is curious that the males should recognize their mates in a guise so unlike their own. How is it that they do not pass them by as members of the totally different distasteful species? Whenever, indeed, the female is more or less brightly liveried than the male, how do the sexes recognize one another, and how, when they live in environments so different as those referred to by Wallace, do they find one another when possessed by the insistent demands of the “sex-hunger” which is the all-essential stimulant to secure the continuation of the race? The factors which assure the satisfaction of this hunger differ in some important features from those which obtain among the higher animals—birds, for example. In the first place there is no necessity to find and hold territory, which is an imperative necessity where there are eggs to be brooded and young to be fed. In the second, the males, as has just been remarked, must search for the females, often indeed, in the case of many Moths, because they are wingless.