Page - 467 - in The Origin of Species

AFFINITIES CONNECTING ORGANIC BEINGS 467 butterfly inhabiting the same district, this variety, from its resemblance to a flourishing and little-persecuted kind, has a better chance of escaping destruction from predaceous birds and insects, and is consequently oftener preserved;— "the less perfect degrees of resemblance being generation after generation eliminated, and only the others left to pro- pagate their kind." So that we have an excellent illus- tration of natural selection. Messrs. Wallace and Trimen have likewise described sev- eral equally striking cases of imitation in the Lepidoptera of the Malay Archipelago and Africa, and with some other in- sects. Mr. Wallace has also detected one such case with birds, but we have none with the larger quadrupeds. The much greater frequency of imitation with insects than with other animals, is probably the consequence of their small size; insects cannot defend themselves, excepting indeed the kinds furnished with a sting, and I have never heard of an instance of such kinds mocking other insects, though they are mocked; insects cannot easily escape by flight from the larger animals which prey on them; therefore, speaking metaphorically, they are reduced, like most weak creatures, to trickery and dissimulation. It should be observed that the process of imitation prob- ably never commenced between forms widely dissimilar in colour. But starting with species already somewhat like each other, the closest resemblance, if beneficial, could read- ily be gained by the above means; and if the imitated form was subsequently and gradually modified through any agency, the imitating form would be led along the same track, and thus be altered to almost any extent, so that it might ulti- mately assume an appearance or colouring wholly unlike that of the other members of the family to which it belonged. There is, however, some difficulty on this head, for it is nec- essary to suppose in some cases that ancient members belong- ing to several distinct groups, before they had diverged to their present extent, accidentally resembled a member of another and protected group in a sufficient degree to afford some slight protection ; this having given the basis for the subsequent acquisition of the most perfect resemblance. On the Nature of the Affinities connecting Organic