es in any country
requires that the species should be placed under favourable conditions of
life, so as to breed freely in that country. When the individuals of any
species are scanty, all the individuals, whatever their quality may be,
will generally be allowed to breed, and this will effectually prevent
selection. But probably the most important point of all, is, that the
animal or plant should be so highly useful to man, or so much valued by
him, that the closest attention should be paid to even the slightest
deviation in the qualities or structure of each individual. Unless such
attention be paid nothing can be effected. I have seen it gravely remarked,
that it was most fortunate that the strawberry began to vary just when
gardeners began to attend closely to this plant. No doubt the strawberry
had always varied since it was cultivated, but the slight varieties had
been neglected. As soon, however, as gardeners picked out individual plants
with slightly larger, earlier, or better fruit, and raised seedlings from
them, and again picked out the best seedlings and bred from them, then,
there appeared (aided by some {42} crossing with distinct species) those
many admirable varieties of the strawberry which have been raised during
the last thirty or forty years.

In the case of animals with separate sexes, facility in preventing crosses
is an important element of success 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 kept true, though mingled in the
same aviary; and this circumstance must have largely favoured the
improvement and 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, cannot be matched, and,
although so much valued by women and children, we hardly ever see a
distinct breed kept up; such breeds as we do sometimes see are almost
always imported from some other country, often from islands. Although I do
not doubt that some domestic animals vary less than others, yet the rarity
or absence of distinct breeds of