wilderness of the New World to appreciate the full significance of a
passage in Belt's _Naturalist in Nicaragua,_ in which it is suggested
that man's hairless condition was perhaps brought about by natural
selection in tropical regions, where he was greatly troubled with
parasites of this kind. It is certain that if in such a country as
Brazil he possessed a hairy coat, affording cover to the tick and
enabling it to get a footing on the body, his condition would be a very
sad one. Savages abhor hairs on the body, and even pluck them off their
faces. This seems like a survival of an ancient habit acquired when the
whole body was clothed with hair; and if primitive man ever possessed
such a habit, nature only followed his lead in giving him a hairless
offspring.

Is it not also probable that the small amount of mammalian life in South
America, and the aquatic habits of nearly all the large animals in the
warmer districts, is due to the persecutions of the tick?

The only way in which a large animal can rid itself of the pest is by
going into the water or wallowing in the mud; and this perhaps accounts
for the more or less aquatic habits of the jaguar, aguara-guazu, the
large Cervus paluclosus, tapir, capybara, and peccary. Monkeys, which
are most abundant, are a notable exception; but these animals have the
habit of attending to each other's skins, and spend a great deal of
their time in picking off the parasites. But how do birds escape the
ticks, since these parasites do not confine their attacks to any one
class of aninials, but attach themselves impartially to any living thing
coming within reach of their hooks, from snake to man? My own
observations bearing on this point refer less to the Ixodes than to the
minute bete-rouge, which is excessively abundant in the Plata district,
where it is known as _bicho colorado,_ and in size and habits resembles