en crossed in each successive generation, in
opposition to the constantly repeated admonition of every breeder. And in
this case, it is not at all surprising that the inherent sterility in the
hybrids should have gone on increasing. If we were to act thus, and pair
brothers and sisters in the case of any pure animal, which from any cause
had the least tendency to sterility, the breed would assuredly be lost in a
very few generations.

Although I do not know of any thoroughly well-authenticated cases of
perfectly fertile hybrid animals, I have some reason to believe that the
hybrids from Cervulus vaginalis and Reevesii, and from Phasianus colchicus
with P. torquatus and with P. versicolor are perfectly fertile. There is no
doubt that these three pheasants, namely, the common, the true ring-necked,
and the Japan, intercross, and are becoming blended together in the woods
of several parts of England. The hybrids from the common and Chinese geese
(A. cygnoides), species which are so different that they are generally
ranked in distinct genera, have often bred in this country with either pure
parent, and in one single instance they have bred _inter se_. This was
effected by Mr. Eyton, who raised two hybrids from the same parents but
from different hatches; and from these two birds he raised no less than
eight hybrids (grandchildren of the pure geese) from one nest. In India,
however, these cross-bred geese must be far more fertile; for I am assured
by two eminently capable judges, namely {254} Mr. Blyth and Capt. Hutton,
that whole flocks of these crossed geese are kept in various parts of the
country; and as they are kept for profit, where neither pure parent-species
exists, they must certainly be highly fertile.

A doctrine which originated with Pallas, has been largely accepted by
modern naturalists; namely, that most of our domestic animals have
descended from two or more wild species, since commingled by intercrossing.
On this view, the aboriginal species must either at first have produced
quite fertile hybrids, or the hybrids must have become in subsequent
generations quite fertile under domestication. This latter alternative
seems to me the most probable, and I am inclined to believe in its truth,
although it rests on no direct evidence. I believe, for instance, that our
dogs have descended from several wild stocks; yet, with perhaps the
exception of certain indigenous domestic dogs of South America, all are
quite fert