en one species is crossed with another and when one
variety is crossed with another variety. For instance, I think those
authors are right who maintain that the ass has a prepotent power over
the horse, so that both the mule and the hinny resemble more closely the
ass than the horse; but that the prepotency runs more strongly in the
male than in the female ass, so that the mule, which is an offspring of
the male ass and mare, is more like an ass than is the hinny, which is
the offspring of the female-ass and stallion.

Much stress has been laid by some authors on the supposed fact, that
it is only with mongrels that the offspring are not intermediate in
character, but closely resemble one of their parents; but this does
sometimes occur with hybrids, yet I grant much less frequently than
with mongrels. Looking to the cases which I have collected of cross-bred
animals closely resembling one parent, the resemblances seem chiefly
confined to characters almost monstrous in their nature, and which have
suddenly appeared--such as albinism, melanism, deficiency of tail or
horns, or additional fingers and toes; and do not relate to characters
which have been slowly acquired through selection. A tendency to sudden
reversions to the perfect character of either parent would, also,
be much more likely to occur with mongrels, which are descended from
varieties often suddenly produced and semi-monstrous in character, than
with hybrids, which are descended from species slowly and naturally
produced. On the whole, I entirely agree with Dr. Prosper Lucas, who,
after arranging an enormous body of facts with respect to animals,
comes to the conclusion that the laws of resemblance of the child to its
parents are the same, whether the two parents differ little or much from
each other, namely, in the union of individuals of the same variety, or
of different varieties, or of distinct species.

Independently of the question of fertility and sterility, in all
other respects there seems to be a general and close similarity in the
offspring of crossed species, and of crossed varieties. If we look at
species as having been specially created, and at varieties as having
been produced by secondary laws, this similarity would be an astonishing
fact. But it harmonises perfectly with the view that there is no
essential distinction between species and varieties.

SUMMARY OF CHAPTER.

First crosses between forms, sufficiently distinct to be ranked as
s