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Isabel McCracken 



and that its appearance in the progeny of S xS is coincident with 

 the appearance of B in the progeny of S xS, Its failure to trans- 

 mit S while transmitting B is in harmony with this interpretation. 



The character AB therefore answers to the requirements of 

 MendeHan recessiveness with respect to its behavior toward the 

 alternate characters, S and B; that is, it disappears in a first cross. 

 Since the matings in category a represent merely second generation 

 matings from the sport AB, the data here cannot be consistently 

 compared with the data from matings of true recessives. Beha- 

 vior of AB as a recessive was tested later in the season with extracted 

 AB from hybrids S. 



For fourth generation data, matings were made in the following 

 categories: 



Category a. AB X AB, both parents of AB ancestry, for two gene- 

 rations; that is, second generation from sport parents (Diagram I). 



Category h. B xB, both parents being wholly of AB ancestry, 

 for two generations (Diagram I). 



Category c. SxS, both parents being hybrids from S xAB 

 (Diagram III). 



Category d. S xAB, the S parent being of pure S ancestry for 

 two generations, the other of AB ancestry for two generations. 



The following table gives the results of these matings : 



TABLE III {Fourth Generation) 



* Ancestry of each parent is similar. 



