164 BOARD OF AGRICULTURE. [Jan., 



The presence of the law of variation is by no means in- 

 herently adverse to improvement in breeding. The result de- 

 pends first, on the character of the variation, and second, on 

 the disposition made of the animals which thus vary. Varia- 

 tions are sometimes downward, in other instances they are up- 

 ward. . When downward, the animals should be eliminated. 

 When upward, they should be retained for breeding. Were it 

 not for variations in the direction of improvement, advance in 

 breeding would be impossible. Viewed from this standpoint, 

 the law of variation is a blessing rather than the thorn which 

 it sometimes proves to be. 



The law of atavism is the law which, in transmission, de- 

 termines that the progeny shall be like some remote ancestor. 

 It is probably a branch of the first law of breeding acting in 

 an erratic way. Like the law of variation, it is a disturbing 

 factor in breeding. But it is more disturbing than the former, 

 in that it introduces variations that are undesirable. It resur- 

 rects from out the dead past what the breeders have been 

 trying to eliminate. The frequent occurrence of a white calf 

 in the breeding of Shorthorns which the breeders have been 

 trying to avoid for generations, illustrates the disturbing char- 

 acter of this law. It may be that its existence is intended to 

 compel the breeder to give careful attention to purity in blood 

 lines, since its power wanes in proportion to the increase in 

 the duration of the period covered by pure breeding. 



Having thus briefly outlined these laws, the effort will be 

 made to enlarge on some feature of their practical application 

 to the operations of the breeder, and also of every farmer who 

 breeds even one animal on his farm. The points that will be 

 more particularly dwelt upon are those which relate to the 

 evidence of prepotency in sires, to the improvement of live- 

 stock through upgrading, and to the futility of promiscuous 

 breeding in so far as it relates to the improvement of live 

 stock. 



Prepotency means the power possessed by a parent to trans- 

 mit individual and breed properties to the progeny. The 

 measure of its strength, however, is more evidenced in the 

 former than the latter. Thus it is that prepotent sires produce 

 uniformity in the stud, herd, or flock. The uniformity thus 

 produced is proportionate to the prepotency of the sire and 

 the excellence of the uniformity is at least measurably propor- 



