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XXXVII. 



INTER-ALTERNATIVE AS OPPOSED TO COUPLED 

 MENDELIAN FACTORS: A SOLUTION OP THE AGOUTI- 

 BLACK COLOUR IN RABBITS. 



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

 Professor of Agriculture in the Royal College of Science, Dublin. 



[Read Februauy 25. Published March 27, 1913.] 



In the November number of the Journal of Genetics Professor Punnett deals 

 with that portion of his experiments specially concerned with the agouti-black 

 colour found in rabbits, and gives his solution of the problem. He finds 

 three dominant factors in operation, and,"' as required by the " presence and 

 absence " theory, their three " absences." Then it has to be assumed that 

 two of the three dominant factors are coupled. 



The purpose of the present paper is to bring forward another solution, in 

 which neither coupling nor the " presence and absence " theory need be 

 assumed — the only assumption necessary being that three of the five factors in 

 tlie case are iuter-alteniatives : tliat is, that any one of three can mate with 

 either of the other two in the same way as tlie red, black, and white colours 

 found in cattle can mate any one with either of the other two, or as any one 

 of the colours in horses can mate with any of the others. 



The colours in the case are agouti, black, yellow, tortoise, and agouti- 

 black. The Himalayan parents used were apparently white, with black 

 " points," but they were really black rabbits lacking colour excepting on the 

 parts covered by the " points," for their progeny from whole-coloured rabbits 

 were whole-coloured, and their peculiar markings were inherited by their 

 grandchildren and other descendants in a way to show that they are 

 recessive to whole colour. The Himalayans were never sorted out and 

 counted as regards their true colours, and these added to the other numbers. 

 Usually, however, the other numbers were large enough without them. 



SCIENT. PROC, R.D.S., VOL. XIII., NO. XXXVII. 4 S 



