Let us now briefly consider the steps by which domestic races have
been produced, either from one or from several allied species. Some
little effect may, perhaps, be attributed to the direct action of the
external conditions of life, and some little to habit; but he would be
a bold man who would account by such agencies for the differences of a
dray and race horse, a greyhound and bloodhound, a carrier and tumbler
pigeon. One of the most remarkable features in our domesticated races
is that we see in them adaptation, not indeed to the animal's or
plant's own good, but to man's use or fancy. Some variations useful to
him have probably arisen suddenly, or by one step; many botanists, for
instance, believe that the fuller's teazle, with its hooks, which
cannot be rivalled by any mechanical contrivance, is only a variety of
the wild Dipsacus; and this amount of change may have suddenly arisen
in a seedling. So it has probably been with the turnspit dog; and this
is known to have been the case with the ancon sheep. But when we
compare the dray-horse and race-horse, the dromedary and camel, the
various breeds of sheep fitted either for cultivated land or mountain
pasture, with the wool of one breed good for one purpose, and that of
another breed for another purpose; when we compare the many breeds of
dogs, each good for man in very different ways; when we compare the
game-cock, so pertinacious in battle, with other breeds so little
quarrelsome, with "everlasting layers" which never desire to sit, and
with the bantam so small and elegant; when we compare the host of
agricultural, culinary, orchard, and flower-garden races of plants,
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