s been long domesticated in the East, the gold
and silver carps; and these present great variation, not only of colour
but in the form and structure of the fins and other external organs. In
like manner, the only domesticated insects, hive bees and silkworm
moths, present numbers of remarkable varieties which have been produced
by the selection of chance variations just as in the case of plants and
the higher animals.

_Circumstances favourable to Selection by Man._

It may be supposed, that the systematic selection which has been
employed for the purpose of improving the races of animals or plants
useful to man is of comparatively recent origin, though some of the
different races are known to have been in existence in very early times.
But Mr. Darwin has pointed out, that unconscious selection must have
begun to produce an effect as soon as plants were cultivated or animals
domesticated by man. It would have been very soon observed that animals
and plants produced their like, that seed of early wheat produced early
wheat, that the offspring of very swift dogs were also swift, and as
every one would try to have a good rather than a bad sort this would
necessarily lead to the slow but steady improvement of all useful plants
and animals subject to man's care. Soon there would arise distinct
breeds, owing to the varying uses to which the animals and plants were
put. Dogs would be wanted chiefly to hunt one kind of game in one part
of the country and another kind elsewhere; for one purpose scent would
be more important, for another swiftness, for another strength and
courage, for yet another watchfulness and intelligence, and this would
soon lead to the formation of very distinct races. In the case of
vegetables and fruits, different varieties would be found to succeed
best in certain soils and climates; some might be preferred on account
of the quantity of food they produced, others for their sweetness and
tenderness, while others might be more useful on account of their
ripening at a particular season, and thus again distinct varieties would
be established. An instance of unconscious selection leading to distinct
results in modern times is afforded by two flocks of Leicester sheep
which both originated from the same stock, and were then bred pure for
upwards of fifty years by two gentlemen, Mr. Buckley and Mr. Burgess.
Mr. Youatt, one of the greatest authorities on breeding domestic
animals, says: "There is not a suspi