nce, the ass is crossed with _A.
Indicus_ or with the horse,--animals which have not striped legs,--and the
hybrids have conspicuous stripes on their legs and even on their faces, all
that can be said is, that an inherent tendency to reversion is evolved
through some disturbance in the organisation caused by the act of crossing.

Another form of reversion is far commoner, indeed is almost universal with
the offspring from a cross, namely, to the characters proper to either pure
parent-form. As a general rule, crossed offspring in the first generation
are nearly intermediate between their parents, but the grandchildren and
succeeding generations continually revert, in a greater or lesser degree,
to one or both of their progenitors. Several authors have maintained that
hybrids and mongrels include all the characters of both parents, not fused
together, but merely mingled in different proportions in different parts of
the body; or, as Naudin[113] has expressed it, a hybrid is a living
mosaic-work, in which the eye cannot distinguish the discordant elements,
so completely are they intermingled. We can hardly doubt that, in a certain
sense, this is true, as when we behold in a hybrid the elements of both
species segregating themselves into segments in the same flower or fruit,
by a process of self-attraction or self-affinity; this segregation taking
place either by seminal or by bud-propagation. Naudin further believes that
the segregation of the two specific elements or essences is eminently
liable to occur in the male and female reproductive matter; and he thus
explains the almost {49} universal tendency to reversion in successive
hybrid generations. For this would be the natural result of the union of
pollen and ovules, in both of which the elements of the same species had
been segregated by self-affinity. If, on the other hand, pollen which
included the elements of one species happened to unite with ovules
including the elements of the other species, the intermediate or hybrid
state would still be retained, and there would be no reversion. But it
would, as I suspect, be more correct to say that the elements of both
parent-species exist in every hybrid in a double state, namely, blended
together and completely separate. How this is possible, and what the term
specific essence or element may be supposed to express, I shall attempt to
show in the hypothetical chapter on pangenesis.

But Naudin's view, as propounded by him, i