[Letters to Editor]

DR. HALE CARPENTER in his article on mimicry (NATURE, April 27) mentions that it is held by many as an objection to the theory of the evolution of mimetic forms by natural selection that the mimic must be mistaken by the predatory animal for its model, if the resemblance is to be of any use to it, and that therefore slight resemblances will be useless, and the evolution of the perfected resemblance unintelligible. This difficulty, he suggests, may be removed by the consideration that the mimic need only remind the enemy of its model to set up a repulsion in its mind and so escape. He instances our repulsion to a worm, which he attributes to its resemblance in form to a snake, for which we have an ancestral repulsion.