on, the snake that is immune to one kind of venom is also immune to
the other.

But the effect of the venom of the poisonous colubrine snakes is
totally different from, although to the full as deadly as, the effect
of the poison of the rattlesnake or jararaca. The serum that is an
antidote as regards the colubrines. The animal that is immune to the
bite of one may not be immune to the bite of the other. The bite of a
cobra or other colubrine poisonous snake is more painful in its
immediate effects than is the bite of one of the big vipers. The
victim suffers more. There is a greater effect on the nerve-centres,
but less swelling of the wound itself, and, whereas the blood of the
rattlesnake's victim coagulates, the blood of the victim of an elapine
snake--that is, of one of the only poisonous American colubrines--
becomes watery and incapable of coagulation.

Snakes are highly specialized in every way, including their prey. Some
live exclusively on warm-blooded animals, on mammals, or birds. Some
live exclusively on batrachians, others only on lizards, a few only on
insects. A very few species live exclusively on other snakes. These
include one very formidable venomous snake, the Indian hamadryad, or
giant cobra, and several non-poisonous snakes. In Africa I killed a
small cobra which contained within it a snake but a few inches shorter
than itself; but, as far as I could find out, snakes were not the
habitual diet of the African cobras.

The poisonous snakes use their venom to kill their victims, and also
to kill any possible foe which they think menaces them. Some of them
are good-tempered, and only fight if injured or seriously alarmed.
Others are excessively irritable, and on rare occasions will even