ade the first step in the creation of the pouter, carrier, and
fantail-pigeon. Man can create not only anomalous breeds, but others with
their whole structure admirably co-ordinated for certain purposes, such as
the race-horse and dray-horse, or the greyhound. It is by no means
necessary that each small change of structure throughout the body, leading
towards excellence, should simultaneously arise and be selected. Although
man seldom attends to differences in organs which are important under a
physiological point of view, yet he has so profoundly modified some breeds,
that assuredly, if found wild, they would be ranked under distinct genera.

The best proof of what selection has effected is perhaps afforded by the
fact that whatever part or quality in any animal, and more especially in
any plant, is most valued by man, that part or quality differs most in the
several races. This result is well seen by comparing the amount of
difference {427} between the fruits produced by the varieties of the same
fruit-tree, between the flowers of the varieties in our flower-garden,
between the seeds, roots, or leaves of our culinary and agricultural
plants, in comparison with the other and not valued parts of the same
plants. Striking evidence of a different kind is afforded by the fact
ascertained by Oswald Heer,[935] namely, that the seeds of a large number
of plants,--wheat, barley, oats, peas, beans, lentils, poppies,--cultivated
for their seed by the ancient Lake-inhabitants of Switzerland, were all
smaller than the seeds of our existing varieties. Ruetimeyer has shown that
the sheep and cattle which were kept by the earlier Lake-inhabitants were
likewise smaller than our present breeds. In the middens of Denmark, the
earliest dog of which the remains have been found was the weakest; this was
succeeded during the Bronze age by a stronger kind, and this again during
the Iron age by one still stronger. The sheep of Denmark during the Bronze
period had extraordinarily slender limbs, and the horse was smaller than
our present animal.[936] No doubt in these cases the new and larger breeds
were generally introduced from foreign lands by the immigration of new
hordes of men. But it is not probable that each larger breed, which in the
course of time supplanted a previous and smaller breed, was the descendant
of a distinct and larger species; it is far more probable that the domestic
races of our various animals were gradually improved in d