Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

RESEMBLANCES AMONG ANIMALS. 65
most minute examination that I could convince, myself
it was not so.
We need not adduce any more examples to show
how important are the details of form and of colouring
in animals, and that their very existence may often
depend upon their being by these means concealed from
their enemies. This kind of protection is found apparently in every class and order, for it has been noticed
wherever we can obtain sufficient knowledge of the
details of an animal's life-history. It varies in degree,
from the mere absence of conspicuous colour or a
general harmony with the prevailing tints of nature,
up to such a minute and detailed resemblance to inorganic or vegetable structures as to realize the talisman
of the fairy tale, and to give its possessor the power of
rendering itself invisible.
Theory of Protective Colouring.
We will now endeavour to show how these wonderful
resemblances have most probably been brought about.
Returning to the higher animals, let us consider the
remarkable fact of the rarity of white colouring in the
mammalia or birds of the temperate or tropical zones
in a state of nature. There is not a single white landbird or quadruped in Europe, except the few arctic or
alpine species, to which white is a protective colour.
Yet in many of these creatures there seems to be no
inherent tendency to avoid white, for directly they are
domesticated white varieties arise, and appear to thrive
as well as others. We have white mice and rats, white
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