gere_ ("Leave me alone"). There
is nothing out of the question in this theory, but it requires to be
taken in a critical spirit. It leads us to think of "warning colours,"
which are the very opposite of the disguises which we are now studying.
Some creatures like skunks, magpies, coral-snakes, cobras, brightly
coloured tree-frogs are obtrusive rather than elusive, and the theory
of Alfred Russel Wallace was that the flaunting conspicuousness serves
as a useful advertisement, impressing itself on the memories of
inexperienced enemies, who soon learn to leave creatures with "warning
colours" alone. In any case it is plain that an animal which is as safe
as a wasp or a coral-snake can afford to wear any suit of clothes it
likes.

[Illustration: DEAD-LEAF BUTTERFLY (_Kallima Inachis_) FROM INDIA

It is conspicuous on its upper surface, but when it settles down on a
twig and shows the underside of its wings it is practically invisible.
The colouring of the under surface of the wings is like that of the
withering leaf; there are spots like fungas spots; and the venation of
the wings suggests the mid-rib and veins of the leaf. A, showing upper
surface; B, showing under surface; C, a leaf.]

[Illustration: PROTECTIVE RESEMBLANCE BETWEEN A SMALL SPIDER (_to the
left_) AND AN ANT (_to the right_)

As ants are much dreaded, it is probably profitable to the spider to be
like an ant. It will be noted that the spider has four pairs of legs and
no feelers, whereas the ant has three pairs of legs and a pair of
feelers.]

[Illustration: _Photo: J. J. Ward, F.E.S._

THE WASP BEETLE, WHICH, WHEN MOVING AMONGST THE BRANCHES GIVES A
WASP-LIKE IMPRESSION]

[Illustration: HERMIT-CRAB WITH PARTNER SEA-ANEMONES

Hermit-crabs hide their soft tail in the shell of a whelk or some other
sea-snail. But some hermit-crabs place sea-anemones on the back of their
borrowed shell. The sea-anemones mask the hermit-crab and their
tentacles can sting. As for the sea-anemones, they are carried about by
the hermit-crab and they get crumbs from its table. This kind of
mutually beneficial external partnership is called commensalism, i.e.
eating at the same table.]

[Illustration: _Photo: G. P. Duffus._

CUCKOO-SPIT

The white mass in the centre of the picture is a soapy froth which the
young frog-hopper makes, and within which it lies safe both from the
heat of the sun and almost all enemies. After sojourning for a time in
the cuckoo-spit, the fro