e tropical
provinces of South America, there are cattle which have an extremely
rare and fine fur in place of the ordinary pile of hair. Various other
instances could be cited, if necessary, going to show that a
beneficent Creator has implanted in many animals, to a certain extent,
a _power of accommodation_ to the circumstances and conditions amid
which they are reared.

The _supply of food_, whether abundant or scanty, is one of the most
active cases of variation known to be within the control of man. For
illustration of its effect, let us suppose two pairs of twin calves,
as nearly alike as possible, and let a male and a female from each
pair be suckled by their mothers until they wean themselves, and be
fed always after with plenty of the most nourishing food; and the
others to be fed with skimmed milk, hay tea and gruel at first, to be
put to grass at two months old, and subsequently fed on coarse and
innutritious fodder. Let these be bred from separately, and the same
style of treatment kept up, and not many generations would elapse
before we had distinct varieties, or breeds, differing materially in
size, temperament and time of coming to maturity.

Suppose other similar pairs, and one from each to be placed in the
richest blue-grass pastures of Kentucky, or in the fertile valley of
the Tees; always supplied with abundance of rich food, these live
luxuriously, grow rapidly, increase in hight, bulk, thickness, every
way, they early reach the full size which they are capable of
attaining; having nothing to induce exertion, they become inactive,
lazy, lethargic and fat. Being bred from, the progeny resemble the
parents, "only more so." Each generation acquiring more firmly and
fixedly the characteristics induced by their situation, these become
hereditary, and we by and by have a _breed_ exhibiting somewhat of the
traits of the Teeswater or Durhams from which the improved Short-horns
of the present day have been reared.

The others we will suppose to have been placed on the hill-sides of
New England, or on the barren Isle of Jersey, or on the highlands of
Scotland, or in the pastures of Devonshire. These being obliged to
roam longer for a scantier repast grow more slowly, develop their
capabilities in regard to size not only more slowly, but, perhaps, not
fully at all--they become more active in temperament and habit,
thinner and flatter in muscle. Their young cannot so soon shift for
themselves and require more