58 



INHERITANCE IN RABBITS 



(10) The gray rabbit which produced spotted offspring in crosses with albinos 

 was undoubtedly heterozygous in regard to the factor U, for experience has shown 

 (in agreement with Hurst, 105) that uniform pigmentation is in the main domi- 

 nant over spotting. We might then recognize as a tenth variety one of the 

 formula B 2 Br 2 E(R)ACI 2 U(S)Y 2 . 



(n) Had the rabbit in question produced pale-pigmented as well as spotted 

 young (and such we have since derived from this stock of rabbits), we should 

 need to modify the formula as given by writing I(D) instead of I 2 , i, e., intense 

 (dilute recessive). The formula of such a rabbit would be 



B 2 Br 2 E(R)ACI(D)U(S)Y 2 . 



This indicates a heterozygous condition as regards 5 character-units, and 

 rabbits of this formula should be capable of producing 32 different gametic 

 combinations, 16 of which would be visibly expressed in different pigmented 

 varieties, while an equal number lacking the factor C would produce albinos 

 visibly alike but gametically different. 



If, then, we were to carry to its logical conclusion the enumeration of 

 the conceivable different varieties of gray rabbit, all alike in appearance 

 but all different in breeding capacity, i. e., of different zygotic formula, 

 we should need to mention 32 varieties: 8 of these would correspond with 

 the first 8 which have already been enumerated and the existence of which 

 has (except for variety 7) been demonstrated, namely: 



(1) Gray producing gray only. 



(2) Gray producing gray and black. 



(3) Gray producing gray and white. 



(4) Gray producing gray, black, and white. 



(5) Gray producing gray and yellow. 



(6) Gray producing gray, black, yellow, and sooty. 



(7) Gray producing gray, yellow, and white. 



(8) Gray producing gray, black, yellow, sooty, and white. 



Eight other varieties would produce the same sorts of young as these 8, 

 but would produce in addition dilute pigmented ones of the same color 

 types, i. e., blue-grays as well as grays, blues as well as blacks, pale yellows 

 (cream) as well as yellows, and pale sooties as well as sooty yellows. 



The 1 6 remaining varieties would produce the same sorts of young as 

 the 1 6 varieties already described, but would produce spotted as well as 

 uniformly pigmented (self) individuals. 



TABLE 37. 



