y larger, earlier, or better fruit, and
raised seedlings from them, and again picked out the best seedlings and
bred from them, then (with some aid by crossing distinct species)
those many admirable varieties of the strawberry were raised which have
appeared during the last half-century.

With animals, facility in preventing crosses is an important element
in the formation of new races--at least, in a country which is already
stocked with other races. In this respect enclosure of the land plays a
part. Wandering savages or the inhabitants of open plains rarely possess
more than one breed of the same species. Pigeons can be mated for life,
and this is a great convenience to the fancier, for thus many races may
be improved and kept true, though mingled in the same aviary; and this
circumstance must have largely favoured the formation of new breeds.
Pigeons, I may add, can be propagated in great numbers and at a very
quick rate, and inferior birds may be freely rejected, as when killed
they serve for food. On the other hand, cats, from their nocturnal
rambling habits, can not be easily matched, and, although so much valued
by women and children, we rarely see a distinct breed long kept up; such
breeds as we do sometimes see are almost always imported from some other
country. Although I do not doubt that some domestic animals vary less
than others, yet the rarity or absence of distinct breeds of the cat,
the donkey, peacock, goose, etc., may be attributed in main part
to selection not having been brought into play: in cats, from the
difficulty in pairing them; in donkeys, from only a few being kept by
poor people, and little attention paid to their breeding; for recently
in certain parts of Spain and of the United States this animal has been
surprisingly modified and improved by careful selection; in peacocks,
from not being very easily reared and a large stock not kept; in geese,
from being valuable only for two purposes, food and feathers, and more
especially from no pleasure having been felt in the display of distinct
breeds; but the goose, under the conditions to which it is exposed when
domesticated, seems to have a singularly inflexible organisation, though
it has varied to a slight extent, as I have elsewhere described.

Some authors have maintained that the amount of variation in our
domestic productions is soon reached, and can never afterward be
exceeded. It would be somewhat rash to assert that the limit has been