on, I think, is simple: from long-continued
study they are strongly impressed with the differences between the
several races; and though they well know that each race varies slightly,
for they win their prizes by selecting such slight differences, yet they
ignore all general arguments, and refuse to sum up in their minds slight
differences accumulated during many successive generations. May not
those naturalists who, knowing far less of the laws of inheritance than
does the breeder, and knowing no more than he does of the intermediate
links in the long lines of descent, yet admit that many of our domestic
races have descended from the same parents--may they not learn a lesson
of caution, when they deride the idea of species in a state of nature
being lineal descendants of other species?

SELECTION.

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 plant