ost every case in which an animal has been
thoroughly domesticated, parti-coloured and white varieties are produced
and become permanent.

It is also well known that animals in a state of nature produce white
varieties occasionally. Blackbirds, starlings, and crows are
occasionally seen white, as well as elephants, deer, tigers, hares,
moles, and many other animals; but in no case is a permanent white race
produced. Now there are no statistics to show that the normal-coloured
parents produce white offspring oftener under domestication than in a
state of nature, and we have no right to make such an assumption if the
facts can be accounted for without it. But if the colours of animals do
really, in the various instances already adduced, serve for their
concealment and preservation, then white or any other conspicuous colour
must be hurtful, and must in most cases shorten an animal's life. A
white rabbit would be more surely the prey of hawk or buzzard, and the
white mole, or field mouse, could not long escape from the vigilant owl.
So, also, any deviation from those tints best adapted to conceal a
carnivorous animal would render the pursuit of its prey much more
difficult, would place it at a disadvantage among its fellows, and in a
time of scarcity would probably cause it to starve to death. On the
other hand, if an animal spreads from a temperate into an arctic
district, the conditions are changed. During a large portion of the
year, and just when the struggle for existence is most severe, white is
the prevailing tint of nature, and dark colours will be the most
conspicuous. The white varieties will now have an advantage; they will
escape from their enemies or will secure food, while their brown
companions will be devoured or will starve; and as "like produces like"
is the established rule in nature, the white race will become
permanently established, and dark varieties, when they occasionally
appear, will soon die out from their want of adaptation to their
environment. In each case the fittest will survive, and a race will be
eventually produced adapted to the conditions in which it lives.

We have here an illustration of the simple and effectual means by which
animals are brought into harmony with the rest of nature. That slight
amount of variability in every species, which we often look upon as
something accidental or abnormal, or so insignificant as to be hardly
worthy of notice, is yet the foundation of all those