A MENDELIAN EXPERIMENT WITH ABERDEEN- 

 ANGUS AND WEST HIGHLAND CATTLE. 



By J. A. S. WATSON, B.Sc, M.C. 



(With Plate XII.) 



While Mendclian analysis has been very successfully applied to the 

 study of the heredity of the smaller animals and of plants, very little 

 progress has so far been made in the investigation of the mode of in- 

 heritance of the characters of the larger and more important domesticated 

 animals. This fact is of course sufficiently explained by the obvious 

 difficulties — the large financial outlay and the extended period of time 

 necessary to obtain experimental results. It would appear, however, 

 that there is no alternative to the method of tedious breeding experi- 

 ments if the many and important problems connected with animal 

 breeding are to be solved. A certain amount of progress has indeed 

 been made by the study of records contained in herd- and stud-books, 

 but it is certain that the results of such investigations lack the scientific 

 conclusiveness of those of carefully planned and critical experiments. 

 Thus such an apparently simple question as that of the inheritance of 

 the red, white and roan colours in Shorthorn cattle, on which practically 

 unlimited statistical evidence is available, has been investigated by 

 several workers, and three quite distinct Mendelian interpretations 

 have been proposed — by Wilson (1), Laughlin (2), and Wentworth (3), 

 respectively — no one of which gives a complete and satisfactory expla- 

 nation of the facts. 



The present experiment was commenced in 1910; the object laid 

 down was to determine the mode of inheritance, in crosses between 

 Aberdeen-Angus and West Highland Cattle, of the horned and polled 

 conditions, of colour differences, of hair characters and of differences in 

 conformation. The two breeds may be briefly described. The Aberdeen- 

 Angus is black in colour, with the exception that a small amount of 

 white is permissible on the underline behind the umbilicus, and on the 

 end of the tail. It is hornless, with a relatively short, smooth coat, and 

 is of the early-maturing beef type — i.e. short of leg, blocky, wide, heavily 

 fleshed and small boned. With regard to the purity, in the Mendelian 



