726 



THE AMERICAN NATURALIST [Vol. XLV 



kindly supplied the data for the following descriptive 

 pedigree : 



Following the nomenclature of this paper this mating, 

 because each parent had both red and white hairs, would 

 be classed as "roan" by "roan" and the white calf could 

 be accounted for easily; but the case should not be dis- 

 missed so summarily. There are red Shorthorns without 

 a single white hair and, although red hair in and about 

 the ear is quite persistent, there are white Shorthorns 

 without a single red hair. If a mating of such red ani- 

 mals should have been known to have produced a white 

 calf it might be accounted for on the grounds of mutation 

 due to an intrusion de novo of an inhibitory or destroy- 

 ing antibody in quantity sufficient to affect the entire coat. 

 As an alternative possibility, it might be that by chance 

 the duplex red areas (w 2 E 2 ) of one parent were in the 

 homologous areas of the other simplex red (w 2 R r ), a con- 

 dition very remotely, if at all, possible on account of the 

 absence of the reciprocally colored patterns in cattle. 

 However, should it be possible, the process would be as 

 follows : 



