172 FIBST PBINCIPLES OF AGRICULTURE. 



care in breeding. This influence has been so marked as 

 to give rise to the common expression that "feed makes 

 breed." Habit also exercises a marked influence in the 

 development of valuable characteristics, a striking example 

 of which is observed in the breeds of milch cows. The 

 habit of giving milk, which has been encouraged for a 

 long time, has caused a change in the structure and func- 

 tion of the animal. In the early breeds the tendency to 

 secrete milk was not a prominent characteristic; it was 

 only sufficiently developed to satisfy the demands of the 

 young. 



Prepotency, or the superior influence of one parent over 

 the other in determining the character of the offspring, 

 is also a principle which exerts a decided influence in the 

 development and improvement of distinct breeds. Certain 

 breeds, as well as certain animals, possess this characteristic 

 in a marked degree ; that is, the offspring closely resemble 

 this particular breed or animal, whatever may have been 

 the character of the other parent. Among American trot- 

 ting-horses, Eysdyk's Hambletonian showed this power of 

 individual prepotency in a remarkable degree ; his get, as 

 a rule, not only resembling him in color, form, gait, temper, 

 vigor, and endurance, but in nearly every conceivable 

 quality that he possessed. 



Lineage. — Various terms are used to express the birth 

 and descent of animals. " Pure-bred," " thorough-bred," and 

 sometimes " full-blood," are terms used to indicate animals 

 of a distinct and well-defined breed. " Pure-bred " is the 

 only strictly correct term ; " thorough-bred " is the name of 

 a distinct breed of English race-horses, while " full-blood " 

 hardly expresses the idea. 



