228 
DARWINISM 
CHAP. 
or dead leaves on or among which they habitually live. Then 
we have the innumerable special adaptations to the tints and 
forms of leaves, or twigs, or flowers ; to bark or moss ; to rock 
or pebble ; by which such vast numbers of the insect tribes 
obtain protection; and we have seen that these various forms 
of coloration are equally prevalent in the waters of the seas 
and oceans, and are thus coextensive with the domain of life 
upon the earth. The comparatively small numbers which 
possess “terrifying” or “alluring” coloration may be classed 
under the general head of the protectively coloured. 
But under the next head—colour for recognition—we have 
a totally distinct category, to some extent antagonistic or 
complementary to the last, since its essential principle is 
visibility rather than concealment. Yet it has been shown, I 
think, that this mode of coloration is almost equally im¬ 
portant, since it not only aids in the preservation of existing 
species and in the perpetuation of pure races, but was, per¬ 
haps, in its earlier stages, a not unimportant factor in their 
development. To it we owe most of the variety and much 
of the beauty in the colours of animals ; it has caused at 
once bilateral symmetry and general permanence of type; 
and its range of action has been perhaps equally extensive 
with that of coloration for concealment. 
Influence of Locality or of Climate on Colour. 
Certain relations between locality and coloration have long 
been noticed. Mr. Gould observed that birds from inland or 
continental localities were more brightly coloured than those 
living near the sea-coast or on islands, and he supposed that 
the more brilliant atmosphere of the inland stations was the 
explanation of the phenomenon . 1 Many American naturalists 
have observed similar facts, and they assert that the intensity 
of the colours of birds and mammals increases from north to 
south, and also with the increase of humidity. This change 
is imputed by Mr. J. A. Allen to the direct action of the en¬ 
vironment. He says: “In respect to the correlation of intensity 
of colour in animals with the degree of humidity, it would 
perhaps be more in accordance with cause and effect to express 
the law of correlation as a decrease of intensity of colour with 
1 See Origin of Species, p. 107. 
