INHERITANCE OE EECUNDlTr IN DOMESTIC FOWL. 391 



that the great sire, say, of speed or of milk prockiction belongs- 

 to a line having a high genotype with regard to those characters ; 

 then it is to be expected, on the hypothesis under consideration^ 

 that his progeny will tend on the average to be like himself in 

 performance regardless of what he is mated with, because any 

 female to which he is mated will be either of a high genotype 

 like himself or of a lower one. But if genotypic high perform- 

 ance is dominant over g:enotypic lower performance, than all 

 the offspring in the first. generation must approximate to the 

 high condition exemplified in the sire. But this is the very 

 essence of what is called prepotency in actual breeding practice." 



It seems to me that certain of the facts set forth in this paper 

 give strong support to this view. A class i B.P.R. $ {= fL^L-i. 

 fLiLi) will get all high producing daughters (barring physio- 

 logical defects of development) regardless of the females to 

 which he is mated. He will show all the objective phenomena 

 of 'prepotency.' B.P.R. $ 550 is an example of this. A class 

 7 B.P.R. male would, in breeders' parlance, be regarded as less 

 prepotent then a class i male, but, even so, more prepotent than 

 the general run of the flock. 



The essential point here should not be misunderstood. It is 

 not, of course, contended that simple Mendelian 'dominance' in 

 general, and prepotency are tbe same thing. More than that is 

 demanded. It is only suggested that a homozygous dominant 

 individual, when high performance is dominant over .low, has 

 all the objective characteristics of a prepotent individual in the 

 breeder's sense. 



That this suggestion explains all the facts regarding prepo- 

 tence is by no means asserted. It seems to me, however, that 

 it does furnish the explanation for a part of the phenomena at 

 least, and by so much helps towards a final solution, since it 

 brings us nearer to the kernel of the problem. 



7^he practical bearing of these results 



To the practical poultryman the data and conclusions of this 

 paper would appear to have some significance. They make it 

 possible to outline a scheme of breeding for increased egg pro- 

 duction which shall be intelligently directed towards the attain- 

 ment of that end. This, however, is net the place to discuss 

 such a scheme. That will be undertaken later in another place. 



