xv GENERAL ADAPTATIONS 323 



than birds, and there are certainly more to be discovered of 

 the former than of the latter. Bates well observed that the 

 expanded wings of butterflies seemed to have been used by 

 Nature to write thereon the story of the origin of species. 

 To this we may, I think, add that she has also used them, 

 like the pages of some old illuminated missal, to exhibit all 

 her powers in the production, on a miniature scale, of the 

 utmost possibilities of colour-decoration, of colour-variety, 

 and of colour-beauty ; and has done this by a method which 

 appears to us unnecessarily complex and supremely difficult, 

 in order perhaps to lead us to recognise some guiding power, 

 some supreme mind, directing and organising the blind 

 forces of nature in the production of this marvellous 

 development of life and loveliness. 



It must always be remembered that what is produced on 

 the flower, the insect, or the bird, is not colour, but a surface 

 so constituted in its chemical nature or mechanical texture 

 as to reflect light of certain wave-lengths while absorbing or 

 neutralising all others. Colour is the effect produced on 

 our consciousness by light of these special wave-lengths. 

 To claim that the lower animals, especially the mammals, 

 perceive all the shades and intensities, the contrasts and the 

 harmonies of colours as we perceive them, and that they 

 are affected as we are with their unequalled beauty is a 

 wholly unjustified hypothesis. The evidence that such 

 sensations of colour exist in their case is wholly wanting. 

 All we really know is, that they appear to perceive differences 

 where we perceive colour, but it has not been proved how 

 far this perception extends, since in the most intelligent of 

 these, dogs and horses, the sense of smell is so highly 

 developed as for many purposes to take the place of vision. 



It is a very suggestive fact that the theory of the develop- 

 ment of the colour-sense through its utility, receives least 

 support from those animals which are nearest to us, and 

 from which we have been corporeally developed the 

 mammals ; rather more support from those which have had 

 a widely different origin the birds ; and apparently most 

 from those farthest removed from us the insects, for whom 

 it has been claimed that we owe them all the floral beauty 

 of the vegetable kingdom, through their refined perception of 



