protection. It is certain that domestic animals are frequently lost here
through snake-bites. The most common poisonous species--the
Craspedo-cephalus alternatus, called _Vivora de la Cruz_ in the
vernacular--has neither bright colour nor warning rattle to keep off
heavy hoofs, and is moreover of so sluggish a temperament that it will
allow itself to be trodden on before stirring, with the result that its
fangs are not infrequently struck into the nose or foot of browsing
beast. Considering, then, the conditions in which C. campestris is
placed--and it might also be supposed that venomous snakes have in past
times been much more numerous than they are now--it is not impossible to
believe that the powerful smell it emits has been made protective,
especially when we see in other species how repulsive odours have been
turned to account by the principle of natural selection.

After all, perhaps the wild naturalist of the pampas knows what he is
about when he ties a strip of deer-skin to the neck of his steed and
turns him loose to graze among the snakes.

The gaucho also affirms that the deer cherishes a wonderful animosity
against snakes; that it becomes greatly excited when it sees one, and
proceeds at once to destroy it; _they say,_ by running round and round
it in a circle, emitting its violent smell in larger measure, until the
snake dies of suffocation. It is hard to believe that the effect can be
so great; but that the deer is a snake hater and killer is certainly
true: in North America, Ceylon, and other districts deer have been
observed excitedly leaping on serpents, and killing them with their
sharp cutting hoofs.