differences, and it is in human nature to value any novelty, however
slight, in one's own possession. Nor must the value which would formerly
be set on any slight differences in the individuals of the same species,
be judged of by the value which would now be set on them, after several
breeds have once fairly been established. Many slight differences might,
and indeed do now, arise amongst pigeons, which are rejected as faults
or deviations from the standard of perfection of each breed. The common
goose has not given rise to any marked varieties; hence the Thoulouse
and the common breed, which differ only in colour, that most fleeting of
characters, have lately been exhibited as distinct at our poultry-shows.

I think these views further explain what has sometimes been
noticed--namely that we know nothing about the origin or history of
any of our domestic breeds. But, in fact, a breed, like a dialect of
a language, can hardly be said to have had a definite origin. A man
preserves and breeds from an individual with some slight deviation of
structure, or takes more care than usual in matching his best animals
and thus improves them, and the improved individuals slowly spread in
the immediate neighbourhood. But as yet they will hardly have a distinct
name, and from being only slightly valued, their history will be
disregarded. When further improved by the same slow and gradual process,
they will spread more widely, and will get recognised as something
distinct and valuable, and will then probably first receive a provincial
name. In semi-civilised countries, with little free communication, the
spreading and knowledge of any new sub-breed will be a slow process.
As soon as the points of value of the new sub-breed are once fully
acknowledged, the principle, as I have called it, of unconscious
selection will always tend,--perhaps more at one period than at another,
as the breed rises or falls in fashion,--perhaps more in one district
than in another, according to the state of civilisation of the
inhabitants--slowly to add to the characteristic features of the breed,
whatever they may be. But the chance will be infinitely small of any
record having been preserved of such slow, varying, and insensible
changes.

I must now say a few words on the circumstances, favourable, or the
reverse, to man's power of selection. A high degree of variability is
obviously favourable, as freely giving the materials for selection to
work on; no