52 INHERITANCE IN RABBITS 



(gray, black, and yellow) may have either intense or dilute pigmentation 

 (disregarding intermediate shades, which, however, exist and are heri- 

 table) . Further, each may either have uniform pigmentation or be spotted 

 with white (disregarding differences in the fineness of the spotting, which, 

 however, exist and are heritable). Further, the yellow may have either 

 pigmented or white under surfaces. Even with categories so inclusive 

 as these, the number of visibly different pigmented varieties rises to i6, 

 and since albinos may either have or not have pigmented extremities, the 

 total number of visibly different varieties mounts to i8. 



There is every reason to suppose that each of these i8 varieties may be 

 obtained in a homozygous condition. Most of them, indeed, have been 

 so obtained in our experiments. But for each homozygous condition 

 there are possible several heterozygous conditions. An enumeration of 

 all these is unnecessary, as the number is truly stupendous. With 5 inde- 

 pendently variable characters (the number known to be independently 

 variable in the rabbit) the number of different zygotic combinations theoret- 

 ically possible is 243. 



We shall content ourselves with enumerating the 18 different known 

 gametic combinations, and in giving examples of a few of the different 

 zygotic combinations. 



Gray Type. 

 (i) Gray, found in wild rabbits; gametic composition — 



A C Y E 



I \ / 



I Br 



(2) Blue-gray, same as the foregoing, with the substitution of D (dilute) 



for I (intense). 



(3) Spotted gray, same as i, with the substitution of S (spotted) for U 



(uniform pigmentation). 



(4) Spotted blue-gray, same as 2, with the substitution of S for U. 



Black Type. 



(5) Black, same as i without A, namely, 



f /\ 



C Y E 



t \/ 



(6) Blue (i. e., dilute black), same as 5, with the substitution of D for I. 



(7) Spotted black, same as 5, with the substitution of S for U. 



(8) Spotted blue, same as 6, with the substitution of S for U. 



