s, most useful to man at different
seasons and for different purposes, or so beautiful in his eyes, we
must, I think, look further than to mere variability. We cannot suppose
that all the breeds were suddenly produced as perfect and as useful as
we now see them; indeed, in several cases, we know that this has not
been their history. The key is man's power of accumulative selection:
nature gives successive variations; man adds them up in certain
directions useful to him. In this sense he may be said to make for
himself useful breeds.

The great power of this principle of selection is not hypothetical.
It is certain that several of our eminent breeders have, even within a
single lifetime, modified to a large extent some breeds of cattle and
sheep. In order fully to realise what they have done, it is almost
necessary to read several of the many treatises devoted to this subject,
and to inspect the animals. Breeders habitually speak of an animal's
organisation as something quite plastic, which they can model almost
as they please. If I had space I could quote numerous passages to this
effect from highly competent authorities. Youatt, who was probably
better acquainted with the works of agriculturalists than almost any
other individual, and who was himself a very good judge of an animal,
speaks of the principle of selection as "that which enables the
agriculturist, not only to modify the character of his flock, but to
change it altogether. It is the magician's wand, by means of which
he may summon into life whatever form and mould he pleases." Lord
Somerville, speaking of what breeders have done for sheep, says:--"It
would seem as if they had chalked out upon a wall a form perfect in
itself, and then had given it existence." That most skilful breeder,
Sir John Sebright, used to say, with respect to pigeons, that "he would
produce any given feather in three years, but it would take him
six years to obtain head and beak." In Saxony the importance of the
principle of selection in regard to merino sheep is so fully recognised,
that men follow it as a trade: the sheep are placed on a table and are
studied, like a picture by a connoisseur; this is done three times at
intervals of months, and the sheep are each time marked and classed, so
that the very best may ultimately be selected for breeding.

What English breeders have actually effected is proved by the enormous
prices given for animals with a good pedigree; and these have n