1887.] ON THE PROTECTIVE VALUE OF COLOUR IN INSECTS. 191 



collection of Butterflies in the Solomon and New Hebrides groups, 

 the details of which it was hoped would be laid before the Society 

 at a future meeting. 



The following papers were read : — 



1. The Experimental Proof of the Protective Value of 

 ColoTir and Markings in Insects in reference to their 

 Vertebrate Enemies. By E. B. Poulton, M.A., F.Z.S.^ 

 F.L.S., of Jesus and Keble Colleges, Oxford, Lecturer 

 on Zoology and Comparative Anatomy, St, Mary^s Hos- 

 pital, Paddington. 



[Eeceived Februarj- 23, 1887.] 



Introductory. — In the preparation of a short course of lectures 

 which were delivered at the Royal Institution in the spring of 1886, 

 I had occasion to work up tlie historical aspects of my subject : — 

 " The Nature and Protective Use of Colour in Caterpillars." The 

 results of this inquiry were thus expressed in the introductory part 

 of the first lecture : — " When Darwin was investigating the bright 

 colours of animals, and was elaborating his theory of their explana- 

 tion as of use in courtship, he came across the brilliant colours of 

 certain caterpillars and saw at once that they were a difficulty in the 

 way of the theory. For caterpillars are undeveloped organisms ; 

 the)' have been described as 'embryos leading an independent life," 

 and there is no way of distinguishing the sexes by external colour or 

 structure (except in a very few instances). Therefore we here meet 

 with brilliant colours, often rendering the possessors conspicuous, 

 which cannot be of any use in courtship. Seeing therefore that the 

 bright colours must be of use in some other way, Darwin drew the 

 attention of Wallace to the subject, and asked whether he could 

 suggest any explanation. Wallace accordingly thought over the 

 subject, and considered it as part of the wider question of the varied 

 uses (other than sexual) of brilliant and startling colour, in other 

 stages of insect-life and in numerous instances scattered over the 

 whole animal kingdom, and he finally ventured to predict that birds 

 and other enemies would be found to refuse such conspicuous 

 caterpillars if oifered to them. He believed, in fact, that such larvae 

 are protected by possessing a nauseous taste or smell, and that it is to 

 their advantage to become as conspicuous as possible, so that their 

 enemies are warned against a repeated experience of the disagreeable 

 results which follow from tasting them, that in fact the gaudy 

 colouring acts as an indication of something unpleasant about its 

 possessor. It was then pointed out that, as far as experiment had 

 gone, it had entirely confirmed Wallace's prediction. Conversely 

 Wallace argued that larvae which were inconspicuous, being coloured 



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