228 



Coat-Colour in Rabbits 



gametes dEa from the Himalayan and deA from the yellow. The 

 black ^1 buck {^ 28) on the other hand we shall assume to have been 

 formed by the gametes DEa from the Himalayan, and deA from the 

 yellow, and his zygotic constitution was therefore DdEeAa\ To give 

 the results set out in Table III he was mated with a series of F^ does, 

 presumably all of the constitution ddEeaa, there being no grounds for 

 supposing that their Himalayan father {(^ 8) carried the factor D. To 

 explain the peculiar proportions which occur in that F^ generation one 

 further assumption must be made, viz. that the factors D and E are 

 coupled in the formation of gametes by j/* 28. This assumption I shall 

 hope to justify fully a little further on when I come to deal with the 

 results of other experiments. Whether the coupling is complete or 

 partial there are at present no data for deciding. For the moment it 

 will be assumed to be complete. 



On this scheme then the gametes formed by the F^ ^ are of four 

 kinds, viz. DEA, DEa, deA, dea, and the gametes formed by the 

 F^ %% are of two kinds, viz. dEa and dea. The results following 

 the bringing together of two such series of gametes are shewn in Fig. 1. 



Fig. 1. 



In other words, the F^ generation should consist of agoutis, blacks, 

 agouti-blacks, yellows, and tortoises in the ratio 1:4:1:1:1. The 

 subjoined figures shew how closely the expected results on this scheme 

 tally with the numbers actually found by experiment. 



Experimental data ) 

 from Table III | 



Agouti Black Black-Agouti Yellow Tortoise 



36 113 34 28 30 



Expectation 



30-125 



120-5 



30-125 



30-125 



30-125 



1 It is of course possible that ? 7 may have been DdEEAa, in which case i 28 would 

 have been formed by an ovum DEA fertilised by a spermatozoon dea. 



