Page:The Zoologist, 4th series, vol 4 (1900).djvu/585

Rh 5 That is to say, where the high cerebral development exists which would, according to W.L. Distant, tend to produce mimicry and protective resemblances, precisely there these adaptations are lowly developed as compared with Insecta, where we meet with far less intelligence and far more of the unvarying repetitions of pure instinct, incapable of improvement by learning, and, within their rigid limits, too perfect to require it. Where the conditions are most favourable for "active mimicry," mimetic and cryptic adaptations are least prominent; where they are least favourable, these adaptations become most conspicuous.

6 So far as I have been able to collect evidence, Kallima does not rest on dry and withered leaves, but in situations, such as trunks and branches, in which dead leaves would not attract attention. H.J. Elwes has stated that it freely expands its wings when settled, and looks anything but leaf-like; but this is probably when it is thoroughly on the alert, during the short pauses between successive flights. C. Swinhoe has informed me that it invariably rests head downwards, like a dead leaf hanging by its stalk, so that all the figures and preparations seen in this country representing its natural attitude are wrong.

It is quite impossible to explain the protective attitude of this or any other insect on the principle of "active mimicry," unless we are going arbitrarily to assume that certain defensive activities are to be explained in this way, while others, equally necessary and equally elaborate, cannot be thus interpreted. Consider, for instance, the concealment often brought by the cocoon—the selection of an appropriate situation, the building into the walls of a part of the surrounding surface, &c, &c. Upon the principle of "active mimicry," "the view would be, I suppose, that the ancestral larva spun a cocoon which was not much of a success, and was in consequence attacked by enemies; that the larva observed these attacks, and accordingly improved its cocoon. But that is not the way in which the struggle for existence is waged with insects. If the larva failed, it failed, and that would be the end of the matter. It has no chance of improvement; it has no opportunity of learning by experience. Its only chance of survival is to avoid experience of foes altogether; experience is the most dangerous thing in the world for an edible insect. This becomes still more obvious when we remember that failure or success is almost always determined long after the cocoon is made. The caterpillar, perhaps, spins the cocoon in autumn, but the real stress of competition will come in winter, when insect-eating animals are pressed hard with hunger, and search high and low for food. But the caterpillar is by