as being dangerous, should not exist in Nature._

It is as well here to reply to an objection that will no doubt occur to
many readers--that if protection is so useful to all animals, and so
easily brought about by variation and survival of the fittest, there
ought to be no conspicuously-coloured creatures; and they will perhaps
ask how we account for the brilliant birds, and painted snakes, and
gorgeous insects, that occur abundantly all over the world. It will be
advisable to answer this question rather fully, in order that we may be
prepared to understand the phenomena of "mimicry," which it is the
special object of this paper to illustrate and explain.

The slightest observation of the life of animals will show us, that they
escape from their enemies and obtain their food in an infinite number of
ways; and that their varied habits and instincts are in every case
adapted to the conditions of their existence. The porcupine and the
hedgehog have a defensive armour that saves them from the attacks of
most animals. The tortoise is not injured by the conspicuous colours of
his shell, because that shell is in most cases an effectual protection
to him. The skunks of North America find safety in their power of
emitting an unbearably offensive odour; the beaver in its aquatic habits
and solidly constructed abode. In some cases the chief danger to an
animal occurs at one particular period of its existence, and if that is
guarded against its numbers can easily be maintained. This is the case
with many birds, the eggs and young of which are especially obnoxious to
danger, and we find accordingly a variety of curious contrivances to
protect them. We have nests carefully concealed, hung from the slender
extremities of grass or boughs over water, or placed in the hollow of a
tree with a very small opening. When these precautions are successful,
so many more individuals will be reared than can possibly find food
during the least favourable seasons, that there will always be a number
of weakly and inexperienced young birds who will fall a prey to the
enemies of the race, and thus render necessary for the stronger and
healthier individuals no other safeguard than their strength and
activity. The instincts most favourable to the production and rearing of
offspring will in these cases be most important, and the survival of the
fittest will act so as to keep up and advance those instincts, while
other causes which tend to modify colour a