PDF - Wallace Online

in PROTECTIVE RESEMBLANCES AMONG ANIMALS 87seldom reversed. Going on a little further, we find birds,reptiles, and insects so tinted and mottled as exactly tomatch the rock, or bark, or leaf, or flower, they are accustomedto rest upon, and thereby effectually concealed. Anotherstep in advance, and we have insects which are formed aswell as coloured so as exactly to resemble particular leaves,or sticks, or mossy twigs, or flowers and in these cases ; verypeculiar habits and instincts come into play to aid in thedeception and render the concealment more complete. Wenow enter upon a new phase of the phenomena, and come tocreatures whose colours neither conceal them nor make themlike vegetable or mineral substances; on the contrary, theyare conspicuous enough, but they completely resemble someother creature of a quite different group, while they differmuch in outward appearance from those with which allessential parts of their organisation show them to be reallyclosely allied.They appear like actors or masqueradersdressed up and painted for amusement, or like swindlersendeavouring to pass themselves off for well-known andrespectable members of society. What is the meaning ofthis strange travesty ? Does Nature descend to imposture ormasquerade We ? answer, she does not. Her principles aretoo severe. There is a use in every detail of her handiwork.The resemblance of one animal to another is of exactly thesame essential nature as the resemblance to a leaf, or to bark,or to desert sand, and answers exactly the same purpose. Inthe one case the enemy will not attack the leaf or the bark,and so the disguise is a safeguard ;in the other case it isfound that for various reasons the creature resembled ispassed over, and not attacked by the usual enemies of itsorder, and thus the creature that resembles it has an equallyeffectual safeguard. We are plainly shown that the disguiseis of the same nature in the two cases, by the occurrence in thesame group of one species resembling a vegetable substance,while another resembles a living animal of another group;and we know that the creatures resembled possess an immunityfrom attack, by their being always very abundant,by their being conspicuous and not concealing themselves,and by their having generally no visible means of escape fromtheir enemies ; while, at the same time, the particular quality