that while they are too young to swim they may lie with safety
upon the ground and escape the attention of polar bears; but in the
antarctic regions, where there are few enemies to fear, the young seals,
for instance, are exactly the colour of their parents.

The most remarkable exception of mimetic colouring among the animals of
the polar regions is the sable. Throughout the long Siberian winter he
retains his coat of rich brown fur. His habits, however, are such that
he does not need the protection of colour, for he is so active that he
can easily catch wild birds, and he can also subsist upon wild berries.
The woodchuck of North America retains his coat of dark-brown fur
throughout the long, cold winters. The matter of his obtaining food,
however, is easy, for he lives in burrows, near streams where he can
catch fish and small animals that live in or near the water.

A number of the old-school naturalists believed that when an animal's
colouring assumed the snowy-white coat of its arctic surroundings, this
was due to the natural tendency on the part of its hair and fur to
assume the colourings and tints of their habitat. This, however, is
absolutely false; and no better proof of it can be offered than the case
of the arctic musk-ox, who is far more polar in his haunts than even the
polar bear, and is therefore exposed to the whitening influence of the
wintry regions more than the bear. Yet he never turns white, but is
always brown. The only enemy of this northern-dweller is the arctic
wolf, and against this enemy he is protected by powerful hoofs, thick
hair, and immense horns. He does not need to conceal himself, and
therefore does not simulate the colour of his surroundings.

[Illustration: _American Museum of Natural History, New York_

THE INDIANS CLAIM THAT THE MOTHER BISON FORCED HER CALF TO ROLL OFTEN IN
A PUDDLE OF RED CLAY, SO THAT IT MIGHT BE INDISTINGUISHABLE AGAINST ITS
RED CLAY BACKGROUND.]

[Illustration: _American Museum of Natural History, New York_

THE ZEBRA IS ONE OF THE CLEVEREST OF CAMOUFLAGERS. THE BLACK-AND-WHITE
STRIPES OF HIS BODY GIVE THE EFFECT OF SUNLIGHT PASSING THROUGH BUSHES.]

Mimetic resemblances are worked out with great difficulty, except in
such cases as the nocturnal animals, which simply become one with their
surroundings. Mice, rats, moles, and bats wear overcoats that are very
inconspicuous, and when suddenly approached they appear almost
invisible. Some of the North Amer