394 PRINCIPLES OF STOCK-BREEDING. 



secretion of milk, that has already been noticed, should 

 not be overlooked in this connection, as an improve- 

 ment in the exercise of one of these functions may 

 have a tendency to increase the activity of the other. 

 It is frequently more difficult to avoid defects than 

 to secure a predominance of desirable qualities. Sir 

 John Sebright very truly says : " We must observe 

 the smallest tendency to imperfection in our stock the 

 moment it appears, so as to be able to counteract it 

 before it becomes a defect, as a rope-dancer, to pre- 

 serve his equilibrium, must correct the balance before 

 it is gone too far, and then not by such a motion as 

 will incline it too much to the opposite side. The 

 breeder's success will depend entirely upon the degree 

 in which he may happen to possess this particular 

 talent." l 



The impaired fecundity of certain families in the 

 improved breeds may be attributed to the neglect of 

 this principle. 



As the fecundity of animals is determined to a 

 great extent by heredity, selections from prolific fami- 

 lies will be found advantageous, while the opposite 

 practice will finally result in disappointment. 



Animals having the same constitutional tenden- 

 cies, and kept under the same artificial conditions, 

 may fail to breed when coupled together ; but, as they 

 prove fertile when coupled with animals of other 

 families, the procreative function has not been lost, 

 but made latent by conditions unfavorable to its action. 



It has been suggested by Sir John Sebright a that 



1 " Art of Breeding," p. 6. 



2 Ibid., pp. 16, 17 ; "American Cattle," by R. L. Allen, p. 206. 



