30 CIRCUMSTAjS jES FAVOURABLE TO SELECTION. [Chap. L 



be reared only where the conditions for its propagation are favour- 

 able. When the individuals are scanty, all will be allowed to breed, 

 whatever their quality may be, and this will effectually prevent 

 selection. But probably the most important element is that the 

 animal or plant should be so highly valued by man, that the closest 

 attention is paid to even the slightest deviations in its qualities or 

 structure. 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 

 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 (with some aid by crossing distinct species) those many 

 admirable varieties of the strawberry were raised which have ap- 

 peared 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 en- 

 closure of the land plays a part. Wandering savages or the in- 

 habitants 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 cir- 

 cumstance 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, cannot 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, &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 ; 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 

 bsing valuable only for two purposes, food and feathers, and more 



