re plainly barred across the
legs than is even the pure quagga. Lastly, and this is another most
remarkable case, a hybrid has been figured by Dr. Gray (and he informs
me that he knows of a second case) from the ass and the hemionus; and
this hybrid, though the ass seldom has stripes on its legs and the
hemionus has none and has not even a shoulder-stripe, nevertheless had
all four legs barred, and had three short shoulder-stripes, like those
on the dun Welch pony, and even had some zebra-like stripes on the sides
of its face. With respect to this last fact, I was so convinced that not
even a stripe of colour appears from what would commonly be called an
accident, that I was led solely from the occurrence of the face-stripes
on this hybrid from the ass and hemionus, to ask Colonel Poole whether
such face-stripes ever occur in the eminently striped Kattywar breed of
horses, and was, as we have seen, answered in the affirmative.

What now are we to say to these several facts? We see several very
distinct species of the horse-genus becoming, by simple variation,
striped on the legs like a zebra, or striped on the shoulders like
an ass. In the horse we see this tendency strong whenever a dun tint
appears--a tint which approaches to that of the general colouring of
the other species of the genus. The appearance of the stripes is not
accompanied by any change of form or by any other new character. We see
this tendency to become striped most strongly displayed in hybrids from
between several of the most distinct species. Now observe the case
of the several breeds of pigeons: they are descended from a pigeon
(including two or three sub-species or geographical races) of a bluish
colour, with certain bars and other marks; and when any breed assumes
by simple variation a bluish tint, these bars and other marks invariably
reappear; but without any other change of form or character. When the
oldest and truest breeds of various colours are crossed, we see a
strong tendency for the blue tint and bars and marks to reappear in the
mongrels. I have stated that the most probable hypothesis to account
for the reappearance of very ancient characters, is--that there is
a TENDENCY in the young of each successive generation to produce the
long-lost character, and that this tendency, from unknown causes,
sometimes prevails. And we have just seen that in several species of the
horse-genus the stripes are either plainer or appear more commonly in