emble the ass
than the horse; but that the prepotency runs more strongly in the
male-ass than in the female, so that the mule, which is the 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
mongrel animals alone are born closely like one of their parents; but
it can be shown that this does sometimes occur with hybrids; yet I grant
much less frequently with hybrids 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 by selection. Consequently, sudden reversions to the perfect
character of either parent would be 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 much or little from each other, namely in the union
of individuals of the same variety, or of different varieties, or of
distinct species.

Laying aside 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
species, and their hybrids, are very generally, but not universally,
sterile. The sterility is of all degrees, and is often so slight that
the two most careful experimentalists who have ever lived, have come to
diametrically opposite conclusions in ranking forms by this test. The
sterility is inna