INTRODUCTION 



17 



nevertheless are governed by the same influences as have guided the course of evolution 

 in general. The value of the study of these insects was fully recognized by Bates, who, in the 

 work already quoted, writes : ' On these expanded membranes nature writes, as on a tablet, 

 the story of the modification of species, so truly do all changes of the organization register 

 themselves thereon. ... As the laws of nature must be the same for all beings, the conclusions 

 furnished by this group of insects must be applicable to the whole organic world, therefore 

 the study of butterflies — creatures selected as the types of airiness and frivolity — instead 

 of being despised, will some day be valued as one of the most important branches of Biological 

 Science.' 



Bates's prophecy has been fulfilled, and it is singularly fitting that the great development 

 of the importance of the study has been in connexion with those phenomena of mimetic 

 association for which he himself, guided by Darwinian principles, was the first to offer 

 an explanation. 



In the case of the species of Kallima already described, and in that of the clear-winged 

 moths, we see that the harmless and defenceless insect enjoys a certain amount of respite 

 from the attacks of its insectivorous enemies by its possession of a more or less perfect 

 resemblance eithef to an object in which its would-be captors have no interest, or to some 

 creature which experience teaches is better left alone. 



Having made the acquaintance of these facts we are in a position to consider a further, 

 and in many ways more remarkable, development of mimetic association, and the one 

 which forms the subject of the present work. The case may be broadly outlined as follows : — 



It is found that many Lepidoptera resemble other insects of their own order though 

 belonging to different genera. Butterflies of certain genera resemble other butterflies, or 

 even moths, frequently widely separated from them in generic characteristics. Whilst in 

 some cases such resemblances are slight, general, or, as it may be termed, tentative, in other 

 cases they are carried out not only in the minutest particulars of colour and pattern, but 

 also in similarity of habits and deportment. 



H. W. Bates, who spent many years in collecting on the Amazon, was the first to call 

 attention to this striking phenomenon, and at the same time to suggest an explanation, in 

 a paper which was read before the Linnaean Society in 1861. In it he sets out certain interest- 

 ing facts concerning the Lepidoptera of that region, and suggests as a cause, a process of natural 

 selection which provides the strongest practical evidence in favour of the well-known 

 Darwinian principles of evolution. 



' The most interesting part of the natural history of the Heliconidae is the mimetic 

 analogies of which a great many of the species are the objects.' 



The sentence is a landmark in the study of the Lepidoptera, as it is from this point that 



the author begins his review of the facts of mimicry which came under his notice. The 



importance of the communication is such that it is desirable here to recapitulate the principal 



facts contained in this part of the memoir. When the numerous specimens collected had 



been classified, according to their structural characters, into their proper genera, it was 



observed that the superficial resemblance between butterflies of widely different genera 



was so marked as to call for some explanation beyond that of mere chance. This superficial 



resemblance had been noted by previous authors, but without any attempt at formulating 



a theory which would serve to explain the phenomenon. A great number of the species 



of the Heliconinae are accompanied in the districts they inhabit by generically different 



butterflies which bear a wonderfully accurate resemblance to them in shape, colour, and 



habits. The imitators belong to widely differing groups of Lepidoptera, such as Papilio, 

 1200 c 



