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Show 214 MR. E. B. POULTON ON THE PROTECTIVE [Mar. 1, which have been actually tested, and it is much to be regretted that experimental investigations have not been further extended and recorded in greater detail. The results of the tables of larvse given above have been, in a very small proportion of cases, so directly contrary to a priori expectation that I do not feel confident in bringing forward any instances which have not been tested, although I feel sure that the vast majority of them would yield favourable results. I cannot, therefore, in this paper accept as satisfactory the purely negative evidence that insect-eating Vertebrates have been often seen to catch and eat insects of various kinds, but have not been seen to catch at the same time and place certain highly coloured species which were abundant and slow-flying. At the time when Bates and Wallace first made public their most important conclusions as to tbe meaning of conspicuous coloration and the true significance of mimicry, it was quite right that evidence of all kinds should be brought forward ; but after the lapse of twenty years, we may fairly expect that conclusions which are so important in Biology shall have received the most abundant and complete experimental proof. And I know that lack of detail in the proofs which have been afforded, and the fact that a large part of the evidence brought forward is still founded on mere surmise (however probable may be tbe result of an actual test), have prejudiced the conclusions in the minds of many distinguished biologists, who have come to look upon the whole subject with an undeserved suspicion. I cannot find any record of actual experiments conducted upon the well-known and conspicuous Heliconians and Danaids, and therefore I do not include them in the following list. There is, however, an observation of Meldola's which is of tbe nature of demonstration, and which is so interesting that I quote it in his words:-" It appears that the nauseous character of these. . . . butterflies is to a certain extent retained after death, as I found that in an old collection which had been destroyed by mites, the least mutilated specimens were species of Danais and Euplaa, genera which are known to be distasteful when living and to serve as models for mimicry, see Proc. Ent. Soc. Lond. 1877, p. xii." (Meldola's editorial notes to his translation of Weismann's Essays above referred to, p. 337). This observation (since confirmed by J. Jenner Weir, • Entomologist,' vol. xv. 1882, p. 160) has the same kind of interest as that of Butler upon spiders, drawing attention, as it does, to the possession of a peculiar taste or smell which is recognized as nauseous by animals as widely separated as the mites and spiders are from lizards and birds. And such a consideration enforces the conclusion previously arrived at from other evidence, that when certain insect-eaters neglect the attributes which are respected by others, we see the results of an "acquired taste" produced in the first instance by hunger, and not by an obedience to the dictates of an eccentric preference for what is very universally regarded as disagreeable. Since the above was written, my friend and pupil Mr. E. A. |
