[ 302 



XXII. 



POLYGAMOUS MENDELIA.N FACTORS. 



By JAMES WILSON, M.A., B.Sc, 

 Professor of Agriculture in the Eoj'al College of Science, Dublin. 



[Read May 26. Published June 17, 1914.1 



It is usual for Mendelian factors to mate with one other factor only : that is 

 for dominants to mate with their own recessives and recessives with their 

 own dominants, but with no other. The factors which produce the various 

 colours in horses and cattle are exceptions, however, for any one belonging 

 to either of these species can mate with any other belonging to the same 

 species. This was observed wlien data for a paper " The Inheritance of Coat 

 Colour in Horses"' were being collected in 1910; but at the time it was 

 not realized that the phenomenon was extraordinary and required special 

 demonstration ; and two years later, a second paper, " The Inheritance 

 of the Dun Coat Colour iu Horses,"^ was written without it being yet 

 realized tliat the behaviour of the factors under consideration would have to 

 be demonstrated. 



Soon afterwards, however, it was seen, from the conclusions which other 

 workers were arriving at, that the observation would have to be stated again 

 with such proof as could be gathered. Accordinglj'^ it was decided to collect 

 more data with regard to the crucial colours ; and this was being done, as time 

 permitted, until, when Dr. A. R. Walther kindly sent a copy of his 

 "Beitrage zur Kentniss der Vererbung der Pferdefarben," published in 

 1912, it was seen that his data together witli those wliicli had been collected 

 would be sufficient. 



The earliest data pertinent to the question are those collected from the 

 German royal studs at Ivenack and Trakehnen by Dr. M. Wilckens and 

 Dr. H. Cramps and published in the " Landwirtschaftliehe Jahrbiicher " in 



Sci. Proc. Roy. Dublin Soc, vol. xii (N.S.), p. 331. - Uhl., vol. xiii (N.S.), p. 184. 



