INTKODl'CTOKY. 9 



visible; while when flying about in the sunshine and tolerably 

 free from molestation, as it is strong on the wing, the brilliant 

 colours do no great harm ; or possibly, as has been suggested, 

 the highly conspicuous marks upon the corners of the wings 

 attract the attention of birds to a part which may be injured 

 without doing the butterfly much harm. 



It is supposed, therefore, that in cases of this kind there has 

 been a gradual elimination of colour varieties less in harmony 

 than others with the peculiar needs of the insect. 



Plan of Coloration not always Useful to the Animal. 



Any one who has some knowledge of natural history will 

 at once remark that coloration is apparently not always in 

 harmony with the mode of life of the animal; not only are 

 colours and coloration which have no use that can be detected 

 present, but the general plan of coloration is occasionally 

 absolutely dangerous ; so it at least seems. Mr. Romanes has 

 pointed out that the different patterns on the breasts of 

 woodpeckers can have no function; for these birds when in 

 their natural haunts do not show the spotted under surface. 

 The highly conspicuous larvfe of one of our rarer Hawk moths 

 (Deilephila yctlii) must fall an easy prey to creatures that feed 

 upon them, for it has been proved experimentally that they 

 are not, as gaudily-coloured insects often are, distasteful to 

 insect-eating animals; their colours cannot therefore have been 

 acquired " as an advertisement of their inedibility." 



The advocates of the theory of natural selection as applied 

 to coloration are apt to explain cases of this kind by falling back 

 upon our ignorance of so much of natural history : they main- 

 tain that, were we better acquainted with the life and habits 

 of those creatures, some explanation would be forthcoming ; 



