316 



The Journal of Heredity 



Cross E X el 



Cross EiXEi 



Cross el X ei 



Cross EX El 



Cross E'Xei 



If a triple allelomorph series is in- 

 volved between the factors E, E\ and 

 e\ the only types of matings which 

 should give all three phenotypes are 

 E X E, E X eS and E x E^. Such, how- 

 ever, is not actually the case. We 

 find, for example, that there are nine E 

 animals obtained in matings of E^ x E^ 

 individuals in a total of 574 offspring. 

 Similarly, there is one E individual in 

 matings of E' x eMn a total of 477 

 offspring; and finally, there are four E^ 

 individuals in a total of sixty-four 

 progeny produced by e^ x e^ matings. 

 Some, or perhaps all of these exceptions 

 might be explained by errors in re- 

 cording parents or in the stud books. 

 There appears, however, to be another 

 possible explanation which should re- 

 ceive consideration. 



If one examines a large number of 

 specimens of brindle Great Danes, he 

 finds that they vary greatly in the 

 amount of black pigment which they 

 possess. Some of them are so nearly 

 fawn as to have only a small spot of 

 dark hairs, while others are almost 

 indistinguishable from blacks. This is 

 a common condition in all brindle and 

 similar patterns. It is found in yellow 

 mice, tabby cats, and in agouti 

 rabbits, mice, and guinea-pigs. That it 

 is a recognized trouble maker in breeding 

 brindle Great Danes is shown by the 

 following quotation from Leighton (loc. 

 cit.): "When brindle Great Danes have 

 been continuously bred together it has 

 been found that they get darker and 



