ry limited in range and variability, because they can
comfortably subsist only in forests, and in the warmer regions of the
earth. The hog, more sluggish and less intelligent, has an omnivorous
appetite, and no very special requirements of habitat, and so can vary
greatly and extend over a large portion of the earth. Farther, in
connection with this subject it may be observed that the conditions
favorable to variation are also in the case of the higher animals
favorable to domestication, while it may also be affirmed that, other
things being equal, animals in a domesticated state are much more
liable to vary than those in a wild state, and this independent of
intentional selection. Darwin admits this, and gives many examples of
it.

2. Varieties may originate in two different ways. In the case of wild
animals it is generally supposed that they are gradually induced by
the slow operation of external influences; but it is certain that in
domesticated animals they often appear suddenly and unexpectedly, and
are not on that account at all less permanent. A large proportion of
our breeds of domestic animals appear to originate in this way. A very
remarkable instance is that of the "Niata" cattle of the Banda
Orientale, described by Darwin in his "Voyage of a Naturalist." These
cattle are believed to have originated about a century ago among the
Indians to the south of the La Plata, and the breed propagates itself
with great constancy. "They appear," says Darwin, "externally to hold
nearly the same relation to other cattle which bull-dogs hold to other
dogs. Their forehead is very short and broad, with the nasal end
turned up, and the upper lip much drawn back; their lower jaws project
outward; when walking they carry their heads low on a short neck, and
their hinder legs are rather longer compared with the front legs than
is usual." It is farther remarkable in respect to this breed that it
is, from its conformation of head, less adapted to the severe droughts
of those regions than the ordinary cattle, and can not, therefore, be
regarded as an adaptation to circumstances. In his later work on
animals under domestication, Darwin gives many other instances of the
origination of breeds of cattle and other animals in this abrupt and
mysterious manner, and without any selection, though he strongly leans
to the conclusion that slow and gradual changes are the most frequent
causes of variation. It is to be observed, however, that ve