the common breed, which differ only in colour, that most fleeting of
characters, have lately been exhibited as distinct at our poultry-shows.

These views appear to explain what has sometimes been noticed, namely, that
we know hardly anything 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 a distinct 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 animals slowly spread in the immediate neighbourhood. But they
will as yet hardly have a distinct name, and from being only slightly
valued, their history will have been disregarded. When further improved by
the same slow and gradual process, they will spread more widely, and will
be 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 of a new sub-breed will be a slow
process. As soon as the points of value are once 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.

CIRCUMSTANCES FAVOURABLE TO MAN'S POWER OF SELECTION.

I will 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; not