sport in Alelasoma and its Behavior in Heredity 229 



produced; that is, broods in which all the individuals are B and 

 mixed broods of B and AB, individuals of B character predomi- 

 nating. In these mixed broods the proportion of B to AB is 3.6 

 to I. This parallels the history of the behavior of S toward B 

 in matings of dominant S hybrids as previously determined. 



In BxB matings (category e, Table II), in which one of the 

 parents was born of AB parents, two kinds of broods also appear; 

 that is, broods in which all the individuals are B, and mixed broods 

 of B and AB, or B, AB and I or B and I, the character B predomi- 

 nating. It is noticeable that in this case, in which one-half as 

 many AB ancestors are represented, the proportion of wholly B 

 broods exceed that of the former cross by about 3 to i, while the 

 proportion of B to AB in mixed broods remains the same, 3.6 to i. 

 In neither case were any broods produced that were wholly AB 

 in character. 



In I xl matings (category /, Table II) mixed broods result in 

 which B is the predominating character, AB taking a second rank 

 and I recurring but rarely, thus showing the heterozygous char- 

 acter of I. 



The hereditary value of the character B in the first generation 

 of a cross between B and AB (that is, B not previously contami- 

 nated by AB) appears from these data to be, therefore, equiva- 

 lent to the hereditary value of pure S to the character B. The 

 hereditary value of pure S and pure B with reference to i\B have 

 the same equivalency. 



The stability of the sport character AB is absolute in neither 

 first nor second generation matings, but comparison of data of 

 first generation mating (Diagram I, category a) with Table II, 

 a, shows an increased preponderance of the sport character in the 

 latter case. AB in the second generation breeds true in more than 

 two-thirds of all broods produced and in all mixed broods greatly 

 predominates in the offspring. It is again noticeable that no S 

 individuals appear in the offspring, although reference to Diagram 

 I shows that as many S as B individuals are represented in the 

 ancestry and reference to Table I shows AB appearing in broods of 

 S xS parentage as well as those of B X B parentage. This sug- 

 gests that the type AB is after all but a new phase of the type B 



