48 CIRCUMSTANCES FAVORABLE TO SELECTION. Chap. I. 



and gradual process, tliey will spread more widely, and will get 

 recognized as sometliing distinct and valuable, and will then 

 probably first receive a provincial name. In semi-civilized 

 countries, with little free communication, the spreading of a 

 new sub-breed would be a slow process. As soon as the points 

 of value in a new strain are once acknowledged, the principle, 

 as I have called it, of unconscious selection will always tend — per- 

 haps more at one period than at another, as the breed rises or 

 falls in fashion — perhaps more in one district than in another, 

 according to the state of civilization of the inhabitants — slowly 

 to add to the characteristic features of the breed, whatever 

 they may be. But the chance may be infinitely small of any 

 record having been jireserved of such slow, varying, and insen- 

 sible changes. 



Circumstances favorable to Mail's Power of Selection. 



I must now say a few words on the circumstances, favor- 

 able, or the reverse, to man's power of selection. A high de- 

 gree of variability is obviously favorable, as freely giving the 

 materials for selection to work on ; not that mere individual 

 differences are not amply sufficient, with extreme care, to allow 

 of the accumulation of a large amount of modification in almost 

 any desired direction. But, as variations manifestly useful or 

 pleasing to man appear only occasionally, the chance of their 

 appearance will be much increased by a large number of indi- 

 viduals being kept ; and hence tliis comes to be of the highest 

 importance to success. On this principle Marshall formerly 

 remarked, with respect to the sheep of parts of Yorkshu-e, that, 

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

 small lots, they never can l)e improved." On the other hand, 

 nurservmen, from raising large stocks of the same plants, arc 

 generally far more successful than amateurs in getting new 

 and valuable varieties. The keejiing of a large number of in- 

 dividuals of a species in any country requires that the species 

 should be placed under favorable conditions of life, so as to 

 breed freely in that countr>', A\^hcn the indi\'iduals of any 

 species are scanty, all the individuals, whatever their quality 

 may be, will generally be allowed to l)reed, and this will effect- 

 ually 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 hy him, that tlie closest at- 

 Irntion is paid to even the slightest dmiation in the qualities 



