518 WHITE— STUDIES OF INHERITANCE IN PISUM. 



Representing purple dotting by one factor simplifies the interpre- 

 tation and amounts to the same thing as Tschermak's two factors 

 since he regards one — the factor E — as absolutely coupled with Gc 

 and A. The other factor (F) is inherited independently of Gc and 

 A, hence may be present in either varieties with colored flowers and 

 colored seed coats or in white-flowered varieties with colorless seed 

 coats. As it expresses itself only in the presence of Gc, its presence 

 in white-flowered races can only be determined by crosses with non- 

 purple-dotted gray seed coat races. The exceptional cases noted 

 above where purple-dotted seed coat fails to appear when expected, 

 are interpreted by Tschermak (86) as due to lack of interaction 

 between the factors F and Gc even though both are present. Non- 

 purple-dotted seed coat races then may be either Gcf (Ef), gcf, 

 gcF — the first colored flowered and the two latter with white flow- 

 ers. GcF (EF) is, exclusive of the exceptional cases noted, always 

 purple dotted. 



Mapling is represented by one factor (54, 55, 86) M, which 

 completely expresses itself only in the presence of Gc, but which 

 may give a faint expression (ghost mapling) in gc white-flowered 

 races. Exceptional cases similar to those found in connection with 

 the inheritance of the purple dot pattern are interpreted by 

 Tschermak (86) in the same way, namely the disassociation in the 

 same plant of M and Gc. M is inherited independently of Gc, F, 

 N and probably PI. 



Brown hilum color may be regarded simply as another expres- 

 sion of Gc since they are absolutely coupled. 



Black eye and violet eye, so far as present data go, are to be re- 

 garded as due to the factors PI and N, both of which are inherited 

 independently of Gc, F, M, and of each other, and able to express 

 themselves in either white- or colored-flowered races. The dom- 

 inance of black eye over non-black eye in one cross and its recessive- 

 ness to non-black eye in another cross involving a different non- 

 black-eyed variety is to be regarded as due to the interference of 

 another factor or factors not yet delineated. 



Data as to the relation of these various factors to each other in 

 inheritance are still much to be desired, especially in the case of PI, 

 U, H and J. While Tschermak has done much toward throwing 



