160 TROPICAL NATURE, AND OTHER ESSAYS. 



gaily-painted wings, or to the humming bird of its 

 jewelled breast, except to add the final touches to a world- 

 picture, calculated at once to please and to refine man- 

 kind ? And even now, with all our recently-acquired 

 knowledge of this subject, who shall say that these old- 

 world views were not intrinsically and fundamentally 

 sound ; and that, although we now know that colour has 

 " uses " in nature that we little dreamt of, yet the relation 

 of those colours or rather of the various rays of light 

 to our senses and emotions, may not be another, and 

 perhaps more important use which they subserve in the 

 great system of the universe ? 



We now propose to lay before our readers a general 

 account of the more recent discoveries on this interesting 

 subject ; and in doing so, it will be necessary first to 

 give an outline of the more important facts as to the 

 colours of organised beings ; then to point out the cases 

 in which it has been shown that colour is of use ; and 

 lastly, to endeavour to throw some light on its nature, 

 and on the general laws of its development. 



Among naturalists, colour was long thought to be of 

 little import, and to be quite untrustworthy as a specific 

 character. The numerous cases of variability of colour led 

 to this view. The occurrence of white blackbirds, white 

 peacocks, and black leopards ; of white blue-bells, and of 

 white, blue, or pink milkworts, led to the belief that colour 

 was essentially unstable, that it could therefore be of 

 little or no importance, and belonged to quite a different 

 class of characters from form or structure. But it now 

 begins to be perceived that these cases, though tolerably 

 numerous, are, after all, exceptional ; and that colour, as 

 a rule, is a constant character. The great majority of 



