388 



s On the Inheritance of Coat Colour in Horses. 



By C. C. Hukst. 



(Communicated by W. Bateson, F.R.S. Received November 4, — Read December 7, 

 1905, — Publication deferred by request of author, December, 1905. — Additional 

 note received February 1, 1906.) 



Recent experiments by the writer have demonstrated the Mendelian 

 inheritance of coat colour in rabbits.* These results suggested that the 

 inheritance of coat colour in horses might also be in accordance with the 

 Mendelian principles. In the case of horses, however, the ordinary method 

 of direct experiment was impracticable, so that recourse was had to the 

 valuable series of records contained in ' Weatherby's General Stud Book of 

 Race Horses.' This work consists of 20 volumes, containing fairly complete 

 records of the age, colour, sex, and parentage of British thoroughbreds from the 

 earliest accounts down to the end of 1904. 



In the modern volumes, at all events, these records have been carefully 

 registered, and with the allowance of a small margin of error, may be safely 

 accepted as scientific evidence, as the results of this paper show. 



Professor Karl Pearson has already made use of this material in his paper 

 " On the Inheritance of Coat Colour in Horses,"! but his statistical methods 

 did not disclose any intrinsic differences in the heredity of the several colour- 

 types. More recently, referring to the inheritance of eye and coat colour, 

 Professor Pearson remarks that : — " Before we leave the cases above it is just 

 worth reiterating that nothing corresponding to Mendel's principles appears 

 in these characters for horses, dogs, and men." 



In regard to thoroughbred horses, he adds : — " It is the same with every 

 coat colour taken, its relative constancy depends largely on the extent to 

 which it has appeared in the ancestry, and one by one black, bay, chestnut, 

 grey must be dismissed by the Mendelian as neither ' recessive ' nor 

 ' dominant,' but as marking ' permanent and incorrigible mongrels.' "I 



A careful examination of the ' Stud Book ' records so far fails to give any 

 support to Professor Pearson's statement : on the contrary, the records show 

 clearly, for instance, that bay and brown are Mendelian dominants to chestnut 



* ' Journ. Linn. Soc. (Zool.),' vol. 29, pp. 283—324 (1905). 

 t ' Phil. Trans.,' A, vol. 195, pp. 79—150 (1900). 

 \ ' Biometrika,' vol. 2, pp. 214, 215 (1903). 



