VI 



THE ABSENCE OF DOMINANCE 



It is well known that every breed of live stock traces 

 back to different varieties and that, at their origin, all 

 breeds are impure in a larger or smaller number of their 

 characters. Breeders prefer certain characters, however, 

 and, by breeding from animals bearing these and dis- 

 carding those bearing others, gradually make their breeds 

 purer and purer in an ever-increasing number of characters. 

 With some characters purity is obtained at once, with 

 others slowly, with others never at all. The breeders of 

 the Suffolk horse, for instance, foimd the chestnuts they 

 preferred throwing no other colour, and, therefore, pure 

 at once in this character. On the other hand, Aberdeen- 

 Angus breeders found their black cattle throwing red 

 calves and Hereford breeders their white-faced cattle 

 throwing calves with coloured faces for many years, in 

 spite of the persistent elimination of calves of the wrong 

 colours. We now know the reasons for these divergent 

 experiences. The chestnut of the Suffolk horse is a 

 recessive and can throw no other colour, while the 

 black colour of the Aberdeen- Angus and the white face 

 of the Hereford are dominants which may carry the 

 factors for their respective recessives unseen and even 

 unsuspected. 



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