ESTABLISHING A FLOCK AND IMPROVING IT 457 



important influence on stamina in the flock, on prolifi- 

 cacy and on maturity. 



Selection is an indirect rather than a direct agent in 

 effecting improvement. It does not directly improve the 

 individual as the sire does or as food does, but it makes 

 further improvement possible in the individuals that shall 

 be born in the flock, through discarding the inferior and 

 retaining the superior for future breeding. It thus aids 

 materially in effecting improvement and in bringing about 

 a higher uniformity. 



Food effects improvement by the direct influence 

 which it exerts upon the entire organism of the individ- 

 uals in the flock. It powerfully influences size, wool pro- 

 duction and stamina and it exerts a far-reaching influence 

 on the functions pertaining to reproduction and the sus- 

 tenance of the progeny. It is the supplement and also 

 the complement of the other agencies used in effecting 

 improvement, and unless it is furnished in liberal supply 

 all attempts to improve the flock will fail. 



Improvement through the sires — As already inti- 

 mated, improvement coming from the sires arises from 

 their potency in the transmission of desirable qualities. 

 Of course, in breeding pure breds, the sires will all be 

 chosen from the same breed. In breeding grades, the 

 choice of the breed from which the sires shall be taken 

 rests entirely with the owner. Some of the owners of 

 grade flocks select the successive sires used from the same 

 pure breed, others select for a longer or a shorter period, 

 first from one breed and then another. The former 

 method is very much superior to the latter. By the first 

 method improvement will be continuous until the average 

 of the animals of the flock reaches the level in their individ- 

 uality of the average of the breed from which the sires 

 have been chosen. This method of breeding makes more 

 and more stable the properties possessed by each succeed- 

 ing generation. By the second method the tendency is to 

 render more and more unstable the elements of inherit- 



