ALLEN. — THE HEREDITY OF COAT COLOR IN MICE. 



83 



This table shows that the chance unions of the two sorts of gametes, 

 when produced in equal proportions by both parents, give the three pos- 

 sible classes, D, D(R), and 11 in approximately the proportions 1:2:1. 



A similar series of drawings was made for Table II (page 87), which 

 represents the offspring of heterozygous and albino parents. In this 

 case, where aa equality of the two classes is expected, one bag contained 

 only unmarked beans representing gametes of the albino parent. The 

 following table (F) gives the results obtained : 



TABLE F. 



-N 2. Spotted mice and cdbinos. In a former paper it has been shown 

 (Castle and Allen, : 03) that the piebald mouse, having areas of pig- 

 mented and non-pigmented integument, is a distinct type, or "mutation," 

 and the gametes formed by such an animal are in the nature of a mosaic 

 of the two alternative characters. Such mosaic gametes act in heredity 

 as unit characters, and the pigment-albino mosaic is dominant over ga- 

 metes representing complete albinism. Crosses in which one of the 

 parents is a spotted animal and the other a complete albino may there- 

 fore be legitimately considered in investigating the behavior of the 

 unpigmented condition toward a character dominant over it. 



In the experiments of the writer, a number of young were obtained by 

 breeding together pure mosaics and albinos. The result was in every 

 case complete dominance of the pigmented condition; in most cases the 

 recessive element of the mosaic disappeared altogether from the soma. 

 The behavior of the mosaic condition will be taken up in greater detail 

 farther on. The important point in the present connection is that the 

 albino character contained in one of the conjugating gametes becomes 

 recessive towards the mosaic character, so that from the union just de- 



