42 SUMMARY 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 re- 

 spect 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 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. 



