140 NATURAL SELECTION VI 
this subject, I would again respectfully urge that they must 
grapple with the whole of the facts, not one or two of them 
only. It will be admitted that, on the theory of evolution 
and natural selection, a wide range of facts with regard to 
colour in nature have been co-ordinated and explained. Until 
at least an equally wide range of facts can be shown to be in 
harmony with any other theory, we can hardly be expected 
to abandon that which has already done such good service, 
and which has led to the discovery of so many interesting 
and unexpected harmonies among the most common (but 
hitherto most neglected and least understood) of the phe- 
nomena presented by organised beings. 
