ften 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 grandparents or more remote ancestors. But this view is
hardly conceivable. If, however, we suppose that every character is derived
{51} exclusively from the father or mother, but that many characters lie
latent in both parents during a long succession of generations, the
foregoing facts are intelligible. In what manner characters may be
conceived to lie latent, will be considered in a future chapter to which I
have lately alluded.

* * * * *

_Latent Characters._--But I must explain what is meant by characters lying
latent. The most obvious illustration is afforded by secondary sexual
characters. In every female all the secondary male characters, and in every
male all the secondary female characters, apparently exist in a latent
state, ready to be evolved under certain conditions. It is well known that
a large number of female birds, such as fowls, various pheasants,
partridges, peahens, ducks, &c., when old or diseased, or when operated on,
partly assume the secondary male characters of their species. In the case
of the hen-pheasant this has been observed to occur far more frequently
during certain seasons than during others.[116] A duck ten years old has
been known to assume both the perfect winter and summer plumage of the
drake.[117] Waterton[118] gives a curious case of a hen which had ceased
laying, and had assumed the plumage, voice, spurs, and warlike disposition
of the cock; when opposed to an ene