CONTRIBITED ARTICLES. 



INHERITANCE IN RACE HORSES. 



Coat Colour. 



By ROBERT BUNSOW. 



Previous publications* have shown that bay^ 

 coloured thoroughbred horses may be either pure 

 with regard to the hereditary transmission of this 

 colour, and will therefore transmit no other colour 

 to their offspring, or they may be impure and will 

 transmit some other alternative colour, such as 

 chestnut. Since bay horses may thus carry in 

 their hereditary mechanism some colour which is 

 not visibly manifested in the presence of the bay 

 colour, we speak of this latter, in Mendelian 

 language, as a dominant colour, while chestnut 

 is spoken of as a recessive. 



I have just now used the term "hereditary 

 mechanism." What is meant by that ? I will 

 endeavour to explain. The cells that form 

 the tissues of an animal or plant which reproduces 

 itself by sexual processes may be divided into the 

 body or somatic, and the reproductive, sex or gametic 

 cells. It is these latter which, in sexual reproduc- 

 tion, constitute the hereditary mechanism. They 



* C. C. Hurst. Proceedings Royal Society, Vol. 77B, 1906. 

 1 For the purposes of this article the author h^s used the word 

 bay to include browns. There is no absolute distinction between these 

 colours. Some horses iu Avinter are bay and brown in summer, and 

 some are vice-versa. Others have a colour which cannot be designated 

 by either l)ay or brown, and in the Stud Book are described as " bay or 

 brown." 



