CHAPTER VIII.
THE ORIGIN AND USES OF COLOUR IN ANIMALS 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 experiments--Special or local colour adaptations--Imitation of particular objects--How they have been produced--Special protective colouring of butterflies--Protective resemblance among marine animals--Protection by terrifying 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.