CHAPTER ^^n 



THE ORIGIN AND USES OF COLOUR IN ANBIALS 



The Darwinian theory threw new light on organic colour — The problem to 

 be solved — The constancy of animal colour indicates utility — Colour 

 and environment — Arctic animals white — Exceptions prove the rule — 

 Desert, forest, nocturnal, and oceanic animals — General theories of 

 animal colour — Variable protective colouring — Mr. Poulton's experi- 

 ments—Special or local colour adaptations — Imitation of particular 

 objects — How they have been produced — Special protective colouring 

 of butterflies — Protective resemblance among marine animals — Pro- 

 tection by ten-ifying enemies — Alluring coloration — The coloration 

 of birds' eggs — Colour as a means of recognition — Summary of the 

 preceding exposition — Influence of locality or of climate on colour — 

 Concluding remarks. 



A3I0NG the numerous applications of the Darwinian theory 

 in the interpretation of the complex phenomena presented by 

 the organic world, none have been moie successful, or are more 

 interesting, than those which deal with the colours of animals 

 and plants. To the older school of naturalists colour was a 

 trivial character, eminently unstable and untrustworthy in the 

 determination of species ; and it appeared to have, in most cases, 

 no use or meaning to the objects which displaj^ed it. The 

 bright and often gorgeous coloration of insect, bird, or flower, 

 was either looked upon as having been created for the enjoy- 

 ment of mankind, or as due to unknown and perhaps undis- 

 coverable laws of natiure. 



But the researches of ]\Ir. Darwin totally changed oiu* point 

 of yievr in this matter. He showed, clearly, that some of the 

 colours of animals are useful, some hurtful to them ; and he 

 believed that many of the most brilliant colours were developed 

 by sexual choice ; while hi^ great general principle, that all 



