and polished coat of mail which may
render them unsatisfactory food to such birds as would be able to
capture them. The causes which lead to the development of colour have
been here able to act unchecked, and we see the result in a large
variety of the most gorgeously-coloured insects.

Here, then, with our very imperfect knowledge of the life-history of
animals, we are able to see that there are widely varied modes by which
they may obtain protection from their enemies or concealment from their
prey. Some of those seem to be so complete and effectual as to answer
all the wants of the race, and lead to the maintenance of the largest
possible population. When this is the case, we can well understand that
no further protection derived from a modification of colour can be of
the slightest use, and the most brilliant hues may be developed without
any prejudicial effect upon the species. On some of the laws that
determine the development of colour something may be said presently. It
is now merely necessary to show that concealment by obscure or imitative
tints is only one out of very many ways by which animals maintain their
existence; and having done this we are prepared to consider the
phenomena of what has been termed "mimicry." It is to be particularly
observed, however, that the word is not here used in the sense of
voluntary imitation, but to imply a particular kind of resemblance--a
resemblance not in internal structure but in external appearance--a
resemblance in those parts only that catch the eye--a resemblance that
deceives. As this kind of resemblance has the same effect as voluntary
imitation or mimicry, and as we have no word that expresses the required
meaning, "mimicry" was adopted by Mr. Bates (who was the first to
explain the facts), and has led to some misunderstanding; but there need
be none, if it is remembered that both "mimicry" and "imitation" are
used in a metaphorical sense, as implying that close external likeness
which causes things unlike in structure to be mistaken for each other.

_Mimicry._

It has been long known to entomologists that certain insects bear a
strange external resemblance to others belonging to distinct genera,
families, or even orders, and with which they have no real affinity
whatever. The fact, however, appears to have been generally considered
as dependent upon some unknown law of "analogy"--some "system of
nature," or "general plan," which had guided the Creator in desi