VI COLOURS OF PLANTS 409 
mena of colour in the organic world. I have shown reasons 
for believing that its presence, in some of its infinitely-varied 
hues, is more probable than its absence, and that variation of 
colour is an almost necessary concomitant of variation of struc- 
ture, of development, and of growth. It has also been shown 
how colour has been appropriated and modified both in the 
animal and vegetable worlds for the advantage of the species 
in a great variety of ways, and that there is no need to call 
in the aid of any other laws than those of organic develop- 
ment and “natural selection” to explain its countless modifi- 
cations. From the point of view here taken, it seems at once 
improbable and unnecessary that the lower animals should 
have the same delicate appreciation of the infinite variety 
and beauty, of the delicate contrasts and subtle harmonies of 
colour, which are possessed by the more intellectual races of 
mankind, since even the lower human races do not possess it. 
All that seems required in the case of animals is a perception 
of distinctness or contrast of colours; and the dislike of so 
many creatures to scarlet may perhaps be due to the rarity 
of that colour in nature, and to the glaring contrast it offers 
to the sober greens and browns which form the general cloth- 
ing of the earth’s surface, though it may also have a direct 
irritating effect on the retina. 
The general view of the subject now given must convince 
us that, so far from colour being—as it has sometimes been 
thought to be—unimportant, it is intimately connected with 
the very existence of a large proportion of the species of the 
animal and vegetable worlds. The gay colours of the butter- 
fly and of the Alpine flower which it unconsciously fertilises 
while seeking for its secreted honey, are each beneficial to its 
possessor, and have been shown to be dependent on the same 
class of general laws as those which have determined the 
form, the structure, and the habits of every living thing. 
The complex Jaws and unexpected relations which we have 
seen to be involved in the production of the special colours of 
flower, bird, and insect must give them an additional interest 
for every thoughtful mind; while the knowledge that, in 
all probability, each style of coloration, and sometimes the 
smallest details, have a meaning and a use must add a new 
charm to the study of nature. 
