30 THE ORIGIN OF SPECIES 



merly remarked, with respect to the sheep of part of Yorkshire, 

 "As they generally belong to poor people, and are mostly in small 

 lots, they never can be improved." On the other hand, nursery- 

 men, from keeping large stocks of the same plant, are generally 

 far more successful than amateurs in raising new and valuable 

 varieties. A large number of individuals of an animal or plant can 

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

 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 variations 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 

 appeared during the last half-century. 



With animals, facility in preventing crosses is an important ele- 

 ment 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 favored 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 do- 

 mestic 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 



