230 



Coat-Colour in Rabbits 



zygous for A, while both the bucks and four of the does were certainly 

 heterozygous for E. The remaining doe, G 55, mated with ^ D \2.b 

 gave four agouti and one black among her self-coloured offspring, 

 though as the expectation is only one dilute (yellow or tortoise) in 

 four it is not at all improbable that further testing would have shewn 

 her to be also heterozygous for E. 



G. The Agouti-blacks. 



On the scheme suggested all the agouti-blacks should be of the 

 constitution DdEEAa, and should all produce the four kinds of 

 gametes DEA, DEa, dEA, dEa in equal numbers. The effect of 

 two such similar series of gametes meeting is shewn in Fig. 2 from 

 which it will be seen that the expected result of mating the agouti- 

 blacks together is blacks, agouti-blacks, and agoutis in the ratio 7:6:3. 



Fig. 2. 



There should be no yellows or tortoises from these matings. It must 

 be expressly stated here that this result is based on the assumption 

 that an animal which is homozygous for D is black whether it contains 

 A or not. The test will of course be to cross a series of these F3 blacks 

 with pure black (ddEEaa). In one case out of seven on the average 

 an F3 black (viz. DDEEAA) should give only agouti-blacks as the 



