tc., are little liable
to change, and remain unaffected by the most extreme variations in
other points; and it is, no doubt, in these more essential and
internal parts that the tendency survives to return under favorable
circumstances to the original type.

5. Varieties or races of the same species are fully reproductive with
each other, which is not the case with true species. Mutual sterility
of varieties of the same species is an exceptional peculiarity, if it
ever truly exist; and, on the other hand, the cross-fertilization of
varieties of the same species, whether in animals or plants, tends to
vigorous life, and also to return to the primitive or average type. On
the other hand, intermixture of distinct species rarely, if ever,
occurs freely in nature. It is generally a result of artificial
contrivance. Again, hybrids produced from species known to be distinct
are either wholly barren, or barren _inter se_, reproducing only with
one of the original stocks, and rapidly returning to it; or if ever
fertile _inter se_, which is somewhat doubtful, rapidly run out. It
has been maintained by Pallas and others, and Darwin leans to this
idea, that there is still another possibility, namely, that of the
perfect and continued fertility of such mixed races, especially after
long domestication; but their proofs are derived principally from the
intermixture of the races of dogs and of poultry, which are cases
actually in dispute at present, as to the original unity or diversity
of the so-called species.

If we apply these considerations to man, our conclusion must be that,
even in his bodily frame, he is not merely specifically but ordinally
distinct from other animals, and that the differences between races of
men are varietal rather than specific. This view is confirmed by the
following facts:

1. The case of man is not that of a wild animal; and it presents many
points of difference even from the case of the domesticated lower
animals. According to the Bible history, man was originally fitted to
subsist on fruits, to inhabit a temperate climate, and to be exempt
from the necessity of destroying or contending with other animals.
This view unquestionably accords very well with his organization. He
still subsists principally on vegetable food, is most numerous in the
warmer regions of the earth; and, when so subsisting in these regions,
is naturally peaceful and timid. On the whole, however, his habits of
life are artificia