58 



The Journal ot Heredity 



about one-third of the distance from 

 the tip to the base, so that the outer 

 til in I droops downward. There is 

 cjuite a bit of variation within the breed 

 but this is closely associated with 

 \ariation in the general quality of the 

 animal. That is, the coarser ear more 

 than one-third broken over is usually 

 found on the coarser, rougher animals, 

 while the finer, more pointed ear, 

 broken over less than one-third, is 

 found more often on a lighter-limbed, 

 rangy type of hog. Whether this cor- 

 relation is genetic (linkage) or due 

 simply to the mechanics of growth is 

 not known. 



The twent\-nine Fj p)igs of the Berk- 

 shire X Duroc-Jersey cross, except 

 for one boar and one sow in the first 

 litter (which was sired by a boar not 

 used subsequently, and which was dis- 

 carded for breeding purposes), all pos- 

 sessed ears which were perfectly erect 

 but slightly larger than on Berkshires 

 of equal size. 



Only forty-tvvo Fo indi\iduals were 

 mature enough to detemiine definitely 

 the shape of the ear when the work was 

 discontinued. Of these, only one 

 showed a typical Duroc-Jersey ear, 

 several were intennediate, but the great 

 majority possessed ears as erect as the 

 Berkshire. 



The Fi boar when mated back to 

 his dam, sired three litters totalling 

 thirt\-fi\e pigs, nine of which had 

 li\ed to be as much as si.x months old 

 when the experiment ended. Of 

 these, four had typical Duroc-Jersey 

 ears, one was still undetermined, and 

 four had erect ears. 



The following conclusions in regard 

 to the inheritance of the set of ear 

 seem warranted b\- the data: The t\pi- 

 cal erect ear of the Berkshire is tlomi- 

 nant by at least one and probably not 

 more than three (Fj ratio of forty-one 

 erect or intemiwliate to one of Duroc- 

 Jersey type) principal factors. There 

 may be a number of minor nKxlifying 

 factors for size and c|uality as well as 

 for the amount of breaking over. 

 Neither breed is homozygous through- 

 out for all the factors concerned in the 



