56 The Selection Theory 



among those with unpalatable warning colours. Hence the imitation 

 of different immune species by Papilio dardanus \ 



I regret that lack of space prevents my bringing forward more 

 examples of mimicry and discussing them fully. But from the case 

 of Papilio dardanus alone there is much to be learnt which is of the 

 highest importance for our understanding of transformations. It 

 shows us chiefly what I once called, somewhat strongly perhaps, the 

 omnipotence of natural selection in answer to an opponent who had 

 spoken of its "inadequacy." We here see that one and the same 

 species is capable of producing four or five different patterns of 

 colouring and marking ; thus the colouring and marking are not, as 

 has often been supposed, a necessary outcome of the specific nature 

 of the species, but a true adaptation, which cannot arise as a direct 

 effect of climatic conditions, but solely through what I may call the 

 sorting out of the variations produced by the species, according to 

 their utility. That caterpillars may be either green or brown is 

 already something more than could have been expected according 

 to the old conception of species, but that one and the same butterfly 

 should be now pale yellow, with black; now red with black and 

 pure white ; now deep black with large, pure white spots ; and again 

 black with a large ochreous-yellow spot, and many small white and 

 yellow spots ; that in one sub-species it may be tailed like the ancestral 

 form, and in another tailless like its Danaid model, all this shows a 

 far-reaching capacity for variation and adaptation that we could 

 never have expected if we did not see the facts before us. How 

 it is possible that the primary colour-variations should thus be 

 intensified and combined remains a puzzle even now ; we are 

 reminded of the modern three-colour printing, perhaps similar 

 combinations of the primary colours take place in this case ; in 

 any case the direction of these primary variations is determined by 

 the artist whom we know as natural selection, for there is no 

 other conceivable way in which the model could affect the butterfly 

 that is becoming more and more like it. The same climate sur- 

 rounds all four forms of female; they are subject to the same 

 conditions of nutrition. Moreover, Papilio dardanus is by no means 

 the only species of butterfly which exhibits different kinds of colour- 

 pattern on its wings. Many species of the Asiatic genus Elymnias 

 have on the upper surface a very good imitation of an immune 

 Euploeine (Danainae), often with a steel-blue ground-colour, while the 

 under surface is well concealed when the butterfly is at rest, thus there 

 are two kinds of protective coloration each with a different meaning ! 

 The same thing may be observed in many non-mimetic butterflies, for 

 instance in all our species of Vanessa, in which the under side shows 

 a grey-brown or brownish-black protective coloration, but we do 



