g. If this means that new characters
never spontaneously appear in our domestic races, but that they are all
directly derived from certain aboriginal species, the doctrine is little
less than absurd; for it implies that animals like Italian greyhounds,
pug-dogs, bull-dogs, pouter and fantail pigeons, &c., were able to exist in
a state of nature. But the doctrine may mean something widely different,
namely, that the crossing of distinct species is the sole cause of the
first appearance of new characters, and that without this aid man could not
have formed his various breeds. As, however, new characters have appeared
in certain cases by bud-variation, we may conclude with certainty that
crossing is not necessary for variability. It is, moreover, almost certain
that the breeds of various animals, such as of the rabbit, pigeon, duck,
&c., and the varieties of several plants, are the modified descendants of a
single wild species. Nevertheless, it is probable that the crossing of two
forms, when one or both have long been domesticated or cultivated, adds to
the variability of the offspring, independently of the commingling of the
characters derived from the two parent-forms; and this implies {265} that
new characters actually arise. But we must not forget the facts advanced in
the thirteenth chapter, which clearly prove that the act of crossing often
leads to the reappearance or reversion of long-lost characters; and in most
cases it would be impossible to distinguish between the reappearance of
ancient characters and the first appearance of new characters. Practically,
whether new or old, they would be new to the breed in which they
reappeared.

Gaertner declares,[636] and his experience is of the highest value on
such a point, that, when he crossed native plants which had not been
cultivated, he never once saw in the offspring any new character; but
that from the odd manner in which the characters derived from the
parents were combined, they sometimes appeared as if new. When, on the
other hand, he crossed cultivated plants, he admits that new characters
occasionally appeared, but he is strongly inclined to attribute their
appearance to ordinary variability, not in any way to the cross. An
opposite conclusion, however, appears to me the more probable.
According to Koelreuter, hybrids in the genus Mirabilis vary almost
infinitely, and he describes new and singular characters in the f