ds this point in India, Africa, America and
Europe have placed it beyond all doubt. If it were necessary I could
myself furnish an account of my own observations on this point.

In the same way it has been established by experiment and observation
in the field that in all the great regions of distribution there are
butterflies which are rejected by birds and lizards, their chief
enemies, on account of their unpleasant smell or taste. These
butterflies are usually gaily and conspicuously coloured and thus--as
Wallace first interpreted it--are furnished with an easily
recognisable sign: a sign of unpalatableness or _warning colours_. If
they were not thus recognisable easily and from a distance, they would
frequently be pecked at by birds, and then rejected because of their
unpleasant taste; but as it is, the insect-eaters recognise them at
once as unpalatable booty and ignore them. Such _immune_[48] species,
wherever they occur, are imitated by other palatable species, which
thus acquire a certain degree of protection.

It is true that this explanation of the bright, conspicuous colours
is only a hypothesis, but its foundations--unpalatableness, and the
liability of other butterflies to be eaten,--are certain, and its
consequences--the existence of mimetic palatable forms--conform it in
the most convincing manner. Of the many cases now known I select one,
which is especially remarkable, and which has been thoroughly
investigated, _Papilla dardanus_ (_merope_), a large, beautiful,
diurnal butterfly which ranges from Abyssinia throughout the whole of
Africa to the south coast of Cape Colony.

The males of this form are everywhere _almost_ the same in colour and
in form of wings, save for a few variations in the sparse black
markings on the pale yellow ground. But the females occur in several
quite different forms and colourings, and one of these only, the
Abyssinian form, is like the male, while the other three or four are
_mimetic_, that is to say, they copy a butterfly of quite a different
family the Danaids, which are among the _immune_ forms. In each region
the females have thus copied two or three different immune species.
There is much that is interesting to be said in regard to these
species, but it would be out of keeping with the general tenor of this
paper to give details of this very complicated case of polymorphism in
_P. Dardanus_. Anyone who is interested in the matter will find a full
and exact statement