PRINCIPLES OF BREEDING. 121 



calf would be of the same blood as the parents, or 

 half and half. B\x[ experience shows that such will 

 not be exactly the case. The tendency to degrada- 

 tion is operative ; and to rate such a progeny at 

 0.50 would be higher than the actual value. "This 

 result implies no contradiction to the foregoing 

 rules ; on the contrary, this certain lowering of the 

 standard of purity shows that the pure blood is the 

 essential ameliorator, and that it is obliged at once 

 to overcome the positive resistance offered by the 

 inferior blood, and the continual tendency to return 

 to the original native type. It farther proves, that 

 part of its power is annulled by the single fact of its 

 being mingled with blood less rich ; and that by this 

 Its agency is essentially modified, and its efficiency 

 diminished. Local influences are therefore opposed 

 to the success of such a cross ; the inferior blood is 

 probably indigenous to the country, and the consti- 

 tutional tendency is in favour of the lowest standard 

 of blood. 



It is by applying this course of reasoning to cross- 

 es which have been made between the improved 

 Short Horns imported into this country and our ori- 

 ginal native cattle (the superior grades of which 

 crosses are, by the inexperienced, considered as of 

 about equal value to the thorough-bred animals), 

 that we shall perceive the dif^culty, stated before, 

 of keeping up the purity and value of any created 

 breed by selection from that breed alone. The 

 seeds of degradation are there ; and a degree of vi- 

 gilance, care, and judgment, which but few breeders 

 of cattle can be supposed to possess, is required to 

 prevent the retrograde tendenc5^ The degeneracy 

 may be slow, the good blood in the race ma}'^ retard, 

 but, for the reasons given above, it cannot wholly 

 arrest the progress downward. An occasional, and, 

 perhaps, not unfrequent infusion of the original pure 

 blood can alone do this. 



Wlien once the work of deterioration has coni- 



II— K 



