FURTHER EXPER1MP:NTS ON THE INHERITANCE 

 OF COAT-COLOUR IN RABBITS. 



By R. C. PUNNETT, M.A., F.R.S. 



In an earlier paper published in this Journal' I gave an account 

 of some experiments with rabbits in which it was shewn that the 

 agouti pattern might in certain cases result from the mating of black 

 with black. Until then all the evidence from mice, rats and guinea 

 pigs, as well as from rabbits, pointed to the relation between agouti 

 and black being a simple Mendelian one in which agouti was 

 dominant. The unexpected appearance of agoutis in litters from 

 black parents led to the framing of a hypothesis which may be 

 briefly recapitulated before giving an account of the further experi- 

 ments which I have made during the past two years. On that 

 hypothesis I suggested that we were dealing witii three ftictors, viz. : 



A, the agouti factor which inhibits the full production of black 

 pigment, turning black into agouti, and tortoise into 

 yellow ; 



E, a factor for the exten.sion of the melanic pigment whicli turns 

 yellow into agouti and tortoise into black ; and 



D, a factor which inhibits the operation of the agouti factor, 

 causing the animal to appear almost or quite black even 

 if the agouti factor be present. 



In order to explain the experimental results it was suggested that 

 complete coupling occurs between the factors D and E, so that animals 

 of the constitution DdEe produce only the gametes DE and de. The 



' Jniinial of fh-nelir.i, UU'i, Vol. ii. pp. 221— '238. 



