Sclater for description, the oriole and the
honey-sucker were, previous to close examination, considered to be the
same species.

_Objections to the Theory of Mimicry._

To set forth adequately the varied and surprising facts of mimicry would
need a large and copiously illustrated volume; and no more interesting
subject could be taken up by a naturalist who has access to our great
collections and can devote the necessary time to search out the many
examples of mimicry that lie hidden in our museums. The brief sketch of
the subject that has been here given will, however, serve to indicate
its nature, and to show the weakness of the objections that were at
first made to it. It was urged that the action of "like conditions,"
with "accidental resemblances" and "reversion to ancestral types," would
account for the facts. If, however, we consider the actual phenomena as
here set forth, and the very constant conditions under which they occur,
we shall see how utterly inadequate are these causes, either singly or
combined. These constant conditions are--

1. That the imitative species occur in the same area and occupy
the very same station as the imitated.

2. That the imitators are always the more defenceless.

3. That the imitators are always less numerous in individuals.

4. That the imitators differ from the bulk of their allies.

5. That the imitation, however minute, is _external_ and
_visible_ only, never extending to internal characters or to
such as do not affect the external appearance.

These five characteristic features of mimicry show us that it is really
an exceptional form of protective resemblance. Different species in the
same group of organisms may obtain protection in different ways: some by
a general resemblance to their environment; some by more exactly
imitating the objects that surround them--bark, or leaf, or flower;
while others again gain an equal protection by resembling some species
which, from whatever cause, is almost as free from attack as if it were
a leaf or a flower. This immunity may depend on its being uneatable, or
dangerous, or merely strong; and it is the resemblance to such creatures
for the purpose of sharing in their safety that constitutes mimicry.

_Concluding Remarks on Warning Colours and Mimicry._

Colours which have been acquired for the purpose of serving as a warning
of inedibility, or of the possession of dangerous offensive wea