36o APPENDIX 



mated together their offspring can never contain more than 

 one-half the blood of each. Thus inbreeding can be con- 

 tinued indefinitely, always getting back to the original ratio 

 of one-half of each original parent, but reducing the number 

 of individuals in the immediate ancestry and thus diminish- 

 ing the tendency to variation. On the other hand, if suc- 

 ceeding generations are mated back to the first parents the 

 blood becomes overwhelmingly that of the side chosen. 



The great stumbling-block is that selection is often made 

 because of blood, or points, without regard to stamina. The 

 use of an individual of low vigor may very well be fatal. 

 The choice should always fall on the best specimen among 

 the most vigorous offspring, weaklings, regardless of qual- 

 ity, being discarded. 



It is by this means that the average of the family, toward 

 which individuals gravitate, may be steadily raised. Ex- 

 ceptional specimens are above the mean of the strain, and 

 except in cases of strong prepotency, the offspring are 

 almost certain to revert. It is for this reason that uncom- 

 monly good animals frequently fail to realize expectations 

 as breeders, while many inferior specimens of good blood, 

 being below the average, produce better than themselves. 

 It thus becomes plain that the only way in which lasting 

 improvement can be secured is by raising the average of the 

 strain. The exceptional individuals, which constantly ap- 

 pear, will then push out farther and farther, reaching new 

 levels of excellence. Close observance of family lines and 

 the most exacting selection are the only means known for 

 securing this desirable result 



