THE COLOURS OF ANIMALS AND SEXUAL SELECTION 1 



General Phenomena of Colour in the Organic World Theory of Heat and 

 Light as producing Colour Changes of Colour in Animals produced 

 by Coloured Light Classification of Organic Colours Protective 

 Colours Warning Colours Sexual Colours Normal Colours The 

 Nature of Colour How Animal Colours are produced Colour a 

 normal product of Organisation Theory of Protective Colours- 

 Theory of Warning Colours Imitative Warning Colours The Theory 

 of Mimicry Theory of Sexual Colours Colour as a means of Recog- 

 nition Colour proportionate to Integumentary Development Selec- 

 tion by Females not a cause of Colour Probable use of the Horns 

 of Beetles Cause of the greater Brilliancy of some Female Insects 

 Origin of the Ornamental Plumage of Male Birds Theory of Display 

 of Ornaments by Males Natural Selection as neutralising Sexual 

 Selection Greater Brilliancy of some Female Birds Colour-develop- 

 ment as illustrated by Humming-Birds Theory of Normal Colours 

 Local causes of Colour-development The influence of Locality on 

 Colour in Butterflies and Birds Sense -perception influenced by Colour 

 of the Integuments Summary on Colour-development in Animals. 



General Phenomena of Colour in the Organic World 

 THERE is probably no one quality of natural objects from 

 which we derive so much pure and intellectual enjoyment as 

 from their colours. The heavenly blue of the firmament, the 

 glowing tints of sunset, the exquisite purity of the snowy 

 mountains, and the endless shades of green presented by the 

 verdure-clad surface of the earth, are a never-failing source of 

 pleasure to all who enjoy the inestimable gift of sight. Yet 

 these constitute, as it were, but the frame and background of 



1 A first sketch of this essay appeared in Macmillan's Magazine of Sep^ 

 tember 1877, 



