No. 4.] HEREDITY AND THE DAIRY COW. 13 



have not all been as good as the immediate parents, and this 

 fact will be a drag on the offspring. The pnll of the back 

 ancestors is called " regression " or the '' drag of the race." 

 Some of the offspring may be, and almost always will be, 

 better than the parents, bnt the average of the offspring from 

 parents mneh above the average of the race will be below the 

 parents. The converse is also trne, however ; the average of 

 the offspring from parents below the average of the race 

 will be above their parents. The exceptionally good cow 

 may have calves better than herself, bnt if she has many 

 calves, the average of all their prodnction will be below what 

 she produces. 



The only way to get rid of this " pull of the back ances- 

 tors " is to breed only animals that have a good ancestry. 

 The farther back good animals go, and the smaller the num- 

 ber of poor ones found, the more often will the offspring 

 prove valuable. 



This means that, after all, we are brought back to the old 

 rule, which says to breed only from those animals that have 

 proved of exceptional merit. 



It is possible that the scientist may discover some way of 

 determining factors in the germcells and of combining 

 gametes that will give us a guide to the number of animals 

 of any one grade that may be expected from a particular 

 mating. Dr. Raymond Pearl, of the University of Maine, 

 states that he has a clue to the way in which the gametes 

 are constituted in certain strains of fowls, and that he can 

 predict a certain number of extremely valuable males from 

 a given mating.^ He has also worked out a scheme for pick- 

 ing out these valuable males that will undoubtedly prove of 

 great value to the poultry breeders. Whether or not any 

 such results can be obtained in the work with dairy cattle 

 I am not prepared to say. It is probable, however, that in 

 the near future we will know much better how to select and 

 mate our animals because of the s]ilendld work being done by 

 trained investigators in various parts of the country. 



1 Before the Poultry Association in Lansing, Mich., in June, 1912. 



