42 
SUMMAEY ON VARIATION 
Chap. I. 
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 
bhds 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 the cat, 
the donkey, peacock, goose, &c., 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; 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 hav¬ 
ing been felt in the display of distinct breeds. 
To sum up on the origin of our Domestic Paces of 
