l68 BOARD OF AGRICULTURE. [Jan., 



exceeds that of the dam to transmit hers, because of her weak 

 prepotency. This explains why in the first instance of such 

 mating, the progeny bear so strong a resemblance to the sire. 



The difference in blood elements at the first, as previously 

 stated, may be represented by one hundred. Now, since the 

 progeny inherits far more largely in such breeding from the 

 sire, the difference in those blood elements will have been re- 

 duced more than fifty per cent. So far as the sire is concerned, 

 the progeny will be possessed of far more than fifty per cent, 

 of inherited properties from him. The exact per cent, repre- 

 sented by such inheritance cannot be exactly stated, but it 

 would be approximately correct to say that seventy-five per 

 cent, of properties in the progeny were inherited from the sire, 

 which would leave twenty-five per cent, of the same to be in- 

 herited from the dam. Thus a great stride has been made in 

 the very first mating. The difference in blood elements now 

 between the Southdown sire and progeny will be represented 

 by twenty-five instead of one hundred, as at the first. 



Mate with a Southdown male again and the progeny of the 

 second generation will be possessed of approximately ninety 

 per cent, of Southdown properties ; of the third generation of 

 approximately ninety-seven per cent., and of the fourth gen- 

 eration, of approximately ninety-nine per cent. The progeny 

 of the fifth generation will, in individuality and useful proper- 

 ties, be practically equal to pure bred Southdowns. This won- 

 derful transformation may be accomplished in five generations 

 of such breeding. In other words, the entire common stocks 

 of farm animals in the United States could be transformed 

 within the time named into pure breds, that is, into animals 

 as good as pure breds, for practical uses. At the present time, 

 however, the supply of pure bred sires would be far too little 

 to accomplish such an end within the time. 



Suppose that instead of pure Southdowns, grade South- 

 down sires had been used. If the prepotency of those sires in 

 each instance exceeded that of the dams with which they were 

 mated, then there would be improvement. The improvement 

 would be proportionate to the excess of that prepotency. But 

 even on the supposition that the prepotency of each Southdown 

 male was superior, variable elements would probably appear 

 in the progeny as the outcome of these elements in the sires, 

 and these would in some instances, at least, make improvements 



