and have assigned their reasons
for matching this and that individual. The importance of the great
principle of Selection mainly lies in this power of selecting scarcely
appreciable differences, which nevertheless are found to be transmissible,
and which can be accumulated until the result is made manifest to the eyes
of every beholder.

The principle of selection may be conveniently divided into three kinds.
_Methodical selection_ is that which guides a man who systematically
endeavours to modify a breed according to some predetermined standard.
_Unconscious selection_ is that which follows from men naturally preserving
the most valued and destroying the less valued individuals, without any
thought of altering the breed; and undoubtedly this process slowly works
great changes. Unconscious selection graduates into methodical, and only
extreme cases can be distinctly separated; for he who preserves a useful or
perfect animal will generally breed from it with the hope of getting
offspring of the same character; but as long as he has not a predetermined
purpose to improve the breed, he may be said to be selecting {194}
unconsciously.[442] Lastly, we have _Natural selection_, which implies that
the individuals which are best fitted for the complex, and in the course of
ages changing conditions to which they are exposed, generally survive and
procreate their kind. With domestic productions, with which alone we are
here strictly concerned, natural selection comes to a certain extent into
action, independently of, and even in opposition to, the will of man.

* * * * *

_Methodical Selection._--What man has effected within recent times in
England by methodical selection is clearly shown by our exhibitions of
improved quadrupeds and fancy birds. With respect to cattle, sheep, and
pigs, we owe their great improvement to a long series of well-known
names--Bakewell, Colling, Ellman, Bates, Jonas Webb, Lords Leicester and
Western, Fisher Hobbs, and others. Agricultural writers are unanimous on
the power of selection: any number of statements to this effect could be
quoted; a few will suffice. Youatt, a sagacious and experienced observer,
writes,[443] the principle of selection is "that which enables the
agriculturist, not only to modify the character of his flock, but to change
it altogether." A great breeder of shorthorns[444] says, "In the anatomy of
the shoulder modern breeders have made great impr