peculiar specialized traits are effectively nullified by an opponent.
This is eminently the case with the most dangerous poisonous snakes.
In them a highly peculiar specialization has been carried to the
highest point. They rely for attack and defence purely on their
poison-fangs. All other means and methods of attack and defence have
atrophied. They neither crush nor tear with their teeth nor constrict
with their bodies. The poison-fangs are slender and delicate, and,
save for the poison, the wound inflicted is of a trivial character. In
consequence they are helpless in the presence of any animal which the
poison does not affect. There are several mammals immune to snake-
bite, including various species of hedgehog, pig, and mongoose--the
other mammals which kill them do so by pouncing on them unawares or by
avoiding their stroke through sheer quickness of movement; and
probably this is the case with most snake-eating birds. The mongoose
is very quick, but in some cases at least--I have mentioned one in the
"African Game Trails"--it permits itself to be bitten by poisonous
snakes, treating the bite with utter indifference. There should be
extensive experiments made to determine if there are species of
mongoose immune to both cobra and viper poison. Hedgehogs, as
determined by actual experiments, pay no heed at all to viper poison
even when bitten on such tender places as the tongue and lips and eat
the snake as if it were a radish. Even among animals which are not
immune to the poison different species are very differently affected
by the different kinds of snake poisons. Not only are some species
more resistant than others to all poisons, but there is a wide
variation in the amount of immunity each displays to any given venom.
One species will be quickly killed by the poison from one species of
snake, and be fairly resistant to the poison of another; whereas in
another species the conditions may be directly reversed.