Page:The Zoologist, 4th series, vol 2 (1898).djvu/315

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of which we hear so much, and know so little; a theory well substantiated by facts, but too often scandalized by loose suggestions and more or less ingenious guesses; a doctrine somewhat neglected by zoologists, and far too much in the hands of the evolutionary camp followers,—still demands, in very many details, verification by experiment. Mr. Frank Finn, the Deputy-Superintendent of the Indian Museum, Calcutta, has, since 1894, undertaken this work in the province in which he now resides, and has published the results of thorough and well designed experiments in a series of papers (i.-iv.) in the 'Journal' of the Asiatic Society of Bengal. The details of these experiments, carefully studied, will serve to qualify much current misconception; at the same time the results are not negative, but, on the whole, confirmative. In butterflies the Danainæ are generally considered as highly protected. With birds, Mr. Finn tells us:—"The common Babblers (Crateropus canorus) ate the Danaine butterflies readily enough in the absence of others, but when offered a choice showed their dislike of these 'protected' forms by avoiding them. This avoidance was much more marked when the birds were at liberty, though even so a few of the objectionable butterflies were eaten." "In several cases I saw the birds apparently deceived by mimicking butterflies. The common Babbler was deceived by Nepheronia hippia, and Liothrix by Hypolimnas misippus. The latter bird saw through the disguise of the mimetic Papilio polites, which, however, was sufficient to deceive the Bhimraj and King Crow. I doubt if any bird was impressed by the mimetic appearance of the female Elymnias undularis. But this is not a first-rate imitation, and a mimic is put to a very severe test when offered to a bird in a cage or aviary."

As, a result of the whole series of experiments, the following conclusions are reached by Mr. Finn:—"1. That there is a general appetite for butterflies among insectivorous birds, even though they are rarely seen when wild to attack them.2. That many, probably most, species dislike, if not intensely, at any rate in comparison with other butterflies, the 'warningly-coloured' Danainæ, Acræa violæ, Delias eucharis, and Papilio aristolochiæ; of these the last being the most distasteful, and the Danainæ the least so.3. That the mimics of these are at any rate relatively palatable, and that the mimicry is commonly effectual under natural