COAT CHARACTERS IN GUINEA-PIGS AND RABBITS. 



2 9 



The matings made and their results are : 



That an albino may transmit latent agouti is shown unmistakably by 

 the following case. Albino cf 2060 was purchased from a breeder and 

 his ancestry is wholly unknown to me. But I found on mating him 

 with spotted females not of agouti parentage that a large proportion 

 of his young were agouti-marked, and this proportion proves to be 

 almost exactly one-half. Thus he has produced by 15 different females, 

 which were spotted with black and red (and in some cases also with 

 white), 19 young marked with agouti (in no case with solid black hairs 

 on the body, though frequently with red or white ones) and 18 young 

 marked with black but not with agouti. By the red or red-white 

 females he has produced 3 agouti-marked and 3 black-marked young. 

 The total pigmented young produced by matings with the spotted 

 females are 22 agouti-marked and 21 black-marked, an approximation to 

 equality as close as is possible with an odd number of young. The 

 matings with red and red-white females show that all the gametes 

 formed by c^ 2060 bear the latent character black pigmentation, but 

 that half his gametes transmit it in the agouti combination with red, 

 half in the form of solid or segregated black. 



If this interpretation is correct it should be possible by suitable mat- 

 ings of c? 2060 with hi's descendants, or of the latter inter se, to obtain 

 albinos all of whose gametes would transmit latent agouti. This mat- 

 ter, it is hoped, can soon be given an experimental test. 



In the foregoing case it seems necessary to assume the dominance of 

 agouti pigmentation over the intermingled condition of black and red 

 spots ; indeed, all my experiments support that idea, except possibly 

 those mentioned in discussing the agouti x black cross (p. 26). The 

 alternative dominance which may have occurred in those cases is 

 apparently exceptional, the rule being that agouti pigmentation domi- 

 nates over black or black-red. Alternative dominance can scarcely be 

 invoked to explain the results obtained from the matings of c? 2060, 

 for it would fail to account for the black-red offspring in the matings 

 with red or red-white females. 



