INTRODUCTION 
Colour in Nature and in Organisms — Characters of the 
Colours of Organisms and their General Importance — 
Method of Treatment Adopted. 
To those who have not followed closely recent 
developments of Evolution Theory, the connection 
between Biology and Colour may seem very remote. 
The phenomena of colour, it may be said, are entirely 
the province of the physicist; that the sky is blue 
and the grass green are two facts of similar nature, 
and the one is as inexplicable as the other. So 
in general it may be said that it is simply a fact 
of experience that most objects, whether animate 
or inanimate, present themselves to our eyes as 
coloured, and that it is therefore absurd to separate 
the phenomena of colour as they appear in organisms 
from the similar phenomena of inorganic nature. A 
little reflection will, however, convince every one that 
the biologist cannot afford to be indifferent to the 
colours of the organisms with which he has to deal. 
In the first place, they attract his attention because 
of their frequently great intrinsic beauty and their 
arrangement into patterns and markings which may 
