332 Scientific Proceedi7igs^ Royal Dublin Societij. 



Little or no assistance can be got from history, for the reason that the 

 migrations of the horse and the interactions of race upon race have not yet 

 been clearly traced. Local and breed histories are very unsatisfactory. 

 Large effects are attributed to very small beginnings, and importations of 

 horses from parts of Europe to places in Britain and Ireland are presumed 

 upon the flimsiest evidence. If a writer cannot find some foreign prince to 

 send a present to his friend the King of England or Scotland, or some 

 English or Scots nobleman to import half-a-dozen stallions from Holland 

 or Flanders, he has always the Spanish Armada to fall back upon ; and " it is 

 said" has been tjje foundation-stone of many an essay in equine history. 

 Professor Ridgeway's " Origin and Influence of the Thoroughbred Horse " is 

 tlie outstanding exception ; but some of its conclusions are weakened by the 

 assumption that when two races of different colour unite a new colour may 

 be produced. 



For the present inquiry a jumping-off point had already been fixed by 

 Mr. C. 0. Hurst, wliose paper " On the Inheritance of Coat Colour in 

 Horses" was read before the Royal Society in December, 1905. Mr. Hurst 

 showed chestnut to be recessive to bay and brown : bay and brown being taken 

 together as one colour. A further hint as to the relationship subsisting 

 between grey, bay, and black was afforded by the following communication 

 published in 21ie Breeders' Gazette, an American journal, on the 9th of June, 

 1909 : — " In an experience of over thirty years in using Clydesdale stallions 

 to all sorts of mares I have never known a mare drop a chestnut colt to one 

 of tljem. One of my stallions sired some gray foals from gray mares, but 

 these gray flllies, when mated with, black Percherons, often had bay foals 

 with white feet and stripes." The Clydesdale stallions referred to above 

 were probably bays or browns, for few of any other colour have been 

 imported to America. Thus grey seemed dominant to bay and brown ; and, 

 as these came in between grey and black, it was further probable that black 

 was recessive to bay and brown. The absence of chestnuts, against the 

 expectation raised by Mr. Hurst's conclusion, is not astonishing, since 

 chestnuts have been unpopular among Clydesdales for many years. To test 

 these tentatively-formed theories, an appeal was made to the Shire stud-book, 

 because it contains a fair proportion of all the common colours. The 

 Thoroughbred stud-book, for instance, contains plenty of chestnuts, but it is 

 deficient in blacks, roans, and greys. 



The first inquiry was confined to a tabulation of the colours of the foals 

 entered in the first four volumes and of their sires and dams. After some 

 working it became apparent, by observing how the colours did or did not 

 " contain " each other, that our tentative theory was approximately correct. 



