e birds of the same
family. But in a future chapter we shall see that all such variations
appear to be the indirect result of changes of some kind in the conditions
of life.

Hence, after a long course of domestication, we might expect to see in the
pigeon much individual variability, and occasional sudden variations, as
well as slight modifications from the lessened use of certain parts,
together with the effects of correlation of growth. But without selection
all this would produce only a trifling or no result; for without such aid
differences of all kinds would, from the two following causes, soon
disappear. In a healthy and vigorous lot of pigeons many more young birds
are killed for food or die than are reared to maturity; so that an
individual having any peculiar character, if not selected, would run a good
chance of being destroyed; and if not destroyed, the {214} peculiarity in
question would almost certainly be obliterated by free intercrossing. It
might, however, occasionally happen that the same variation repeatedly
occurred, owing to the action of peculiar and uniform conditions of life,
and in this case it would prevail independently of selection. But when
selection is brought into play all is changed; for this is the
foundation-stone in the formation of new races; and with the pigeon,
circumstances, as we have already seen, are eminently favourable for
selection. When a bird presenting some conspicuous variation has been
preserved, and its offspring have been selected, carefully matched, and
again propagated, and so onwards during successive generations, the
principle is so obvious that nothing more need be said about it. This may
be called _methodical selection_, for the breeder has a distinct object in
view, namely, to preserve some character which has actually appeared; or to
create some improvement already pictured in his mind.

Another form of selection has hardly been noticed by those authors who have
discussed this subject, but is even more important. This form may be called
_unconscious selection_, for the breeder selects his birds unconsciously,
unintentionally, and without method, yet he surely though slowly produces a
great result. I refer to the effects which follow from each fancier at
first procuring and afterwards rearing as good birds as he can, according
to his skill, and according to the standard of excellence at each
successive period. He does not wish permanently to modify the breed; he