all hybrids. The conclusion that the condition of the parent-species, as
affected by culture, is one of the proximate causes leading to reversion,
agrees well with the converse case of domesticated animals and cultivated
plants being liable to reversion when they become feral; for in both cases the
organisation or constitution must be disturbed, though in a very different
way. (13/53. Prof. Weismann in his very curious essay on the different forms
produced by the same species of butterfly at different seasons ('Saison-
Dimorphismus der Schmetterlinge' pages 27, 28), has come to a similar
conclusion, namely, that any cause which disturbs the organisation, such as
the exposure of the cocoons to heat or even to much shaking, gives a tendency
to reversion.)

Finally, we have seen that characters often reappear in purely-bred races
without our being able to assign any proximate cause; but when they become
feral this is either indirectly or directly induced by the change in their
conditions of life. With crossed breeds, the act of crossing in itself
certainly leads to the recovery of long-lost characters, as well as of those
derived from either parent-form. Changed conditions, consequent on
cultivation, and the relative position of buds, flowers, and seeds on the
plant, all apparently aid in giving this same tendency. Reversion may occur
either through seminal or bud generation, generally at birth, but sometimes
only with an advance of age. Segments or portions of the individual may alone
be thus affected. That a being should be born resembling in certain characters
an ancestor removed by two or three, and in some cases by hundreds or even
thousands of generations, is assuredly a wonderful fact. In these cases the
child is commonly said to inherit such characters directly from its
grandparent, or more remote ancestors. But this view is hardly conceivable.
If, however, we suppose that every character is derived exclusively from the
father or mother, but that many characters lie latent or dormant in both
parents during a long succession of generations, the foregoing facts are