WHITE— STUDIES OF INHERITANCE IN PISUM. 515 



Gray zvith purple dots X gray with maple marbling gives in F^ 

 gray, purple-dotted, mapled seed coats. In Fo, Tschermak obtained 

 13 gpm : 13 gp : 12 gm : 2 g. From segregates similar in genetic com- 

 position to the Fi, Tschermak (86) secured 



in F3 — 29 gpm: 9 gp:i6 gm : 6 g, 

 in F^ — 20 gpm -.g gp : 12 gm : i g, 



making in all three generations from Fj plants or segregates of the 



same composition, 



62 gpm: 31 gp:40 gm : 9 g 

 Expected, 79.8 gpm : 26.4 gp : 26.4 gm : 8.8 g 



Ratio, 9 gpm : 3 gp : 3 gm : i g 



Approximation, 6.9 gpm : 3.4 gp : 4.4 gm : i g 



As maples and maples with purple dots are often hard to sep- 

 arate, the disproportion of gpm and gm may be due to this difficulty. 

 9 of the Fo gpm were tested and in F3 : 



I gave all four classes, 



1 gave gpm, gm, g (brown self), 

 4 gave gpm, gp, gm, 



2 gave gpm, gp, 



I gave gm only, only one plant being grown. 



Bateson (i) crossed gray with purple dots X niaple (Irish 

 Mummy). F^ as given above and F. resulted in 4 classes, no ratios 

 or numbers given. The 4 classes are brownish gray with purple 

 dots, maple and purple dots, maple, gray and light purple specks. 

 The first and last classes are probably the same, the difference re- 

 sulting from environment. Great difficulty is experienced in dis- 

 criminating between true browns and brown due to weathering. 



Gray zvith purple dots X self purple gives in F^, self purples 

 (34). In Fo these gave: 



35 self violet or purple : 1 1 gray green, violet dots : 3 gray green. 



The maternal parent of this cross had seeds varying on the same 

 plant through all these classes. The paternal parent was a self- 

 violet variety. 



PROC. AMER. PHIL. SOC, VOL. LVI, HH, DECEMBER lO, I917. 



