INTRODUCTION 



15 



In view of the foregoing facts, the question naturally arises, what is the meaning of 

 these resemblances in nature between a living creature, and in the one case some inanimate 

 object, and in the other some other creature well known to be provided with formidable 

 means of defence, or with equally formidable habits of offence ? How have some butterflies, 

 brightly coloured and conspicuous when flying, become enabled to completely efface them- 

 selves when at rest, and therefore less alert ? 



The doctrine of independent creation, involving the idea that the living things which 

 exist around us were all separately created and brought into being just as we now see 

 them, is one which has been so deeply impressed on the civilized mind, that the early 

 existence of any alternative view may be easily overlooked. Nevertheless, long before 

 the tentative efforts of early naturalists and philosophers culminated in the flood of 

 light in which Darwin and Wallace expounded the mysteries of biological evolution, we 

 find that there were those who sought to explain the formation of what we now call 

 species by natural rather than supernatural agency. In spite, however, of many passages 

 which may be discovered in pre-Darwinian writings, which seem to show an appre- 

 ciation of some system of evolution, it was reserved for Charles Darwin to conceive the 

 formation of species by natural selection, and to expound his argument by a wealth of 

 instance and experiment which forms the subject-matter of his great work on the ' Origin 

 of Species '. 



The principles there explained are too well known to require recapitulation here, 

 since they form the basis of biological study at the present day. What it is desired to 

 emphasize is the fact that it is upon Darwinian principles that it is now sought to explain 

 the colours and forms generally of living creatures, and in particular, that development of 

 the widely exhibited phenomena of mimicry and protective resemblance of which this 

 work treats. 



The whole subject of animal coloration forms a most extensive and interesting study, 

 and much valuable information on the subject will be found in Professor Poulton's work 

 on 'The Colours of Animals'.^ The terms proposed by that author have passed into 

 regular use in dealing with the phenomena of mimicry, and it is necessary, therefore, to 

 give some explanation of their meaning, for which account I am indebted to the work 

 above mentioned. 



Animals may be coloured so as to resemble some portion of their environment, which 

 coloration may serve two purposes, namely, either to hide them from their enemies, or to 

 enable them the more easily to approach their prey. In some cases both purposes may be 

 served in the same animal. These two conditions have long been recognized as Protective 

 and Aggressive Resemblance. Animals may, however, be so coloured as to resemble another 

 species, the latter being distasteful or dangerous, or they may resemble some inanimate 

 or unattractive object. These are known as forms of Protective Mimicry. On the other 

 hand, a dangerous animal may be coloured so as to resemble an innocuous form, or an 

 attractive inanimate object ; these two phenomena constitute Aggressive Mimicry and 

 Alluring Coloration. 



In addition to these we have true Warning and Signalling Colours, by which animals give 

 notice of their dangerous properties or provide an easy method of recognition for other 

 individuals of their own species. Lastly we have Sexual Coloration or the colours which are 

 displayed in courtship. 



1 ' The Colours of Animals ; their Meaning and Use,' Poulton, 1890. 



