WHITE— STUDIES OF INHERITANCE IN PISUM. 569 



bers are too small to throw much light on this possibility. Purple- 

 podded varieties need a much more thorough study before putting 

 them on a factorial basis. Green- and yellow-podded varieties may 

 be provisionally represented as the presence and absence of Gp. 



17. Pod Apices. 



Varieties of peas have either blunt (obtuse) or acute pods. 

 Most curved varieties such as Black-eyed Marrowfat and Scimitar 

 have acute pods, while blunt pods are characteristic of Nott's Ex- 

 celsigr, Gold von Blocksberg, French Gray Sugar, Ringleader and 

 others. These characters are generally most sharply defined in 

 well-'filled pods. In many varieties doubtful pods occur on the 

 same vine with those easily classified. 



Results from Crossing. 



Blunt (stumpy) X acute in F^ always gives all blunt-podded 

 offspring (81, i, 54, 56). In Fo, blunt-podded to acute-podded 

 plants occur in approximately 3 : i proportions. 



Interpretation. 

 The difference between blunt- and acute-podded varieties may 

 be represented by the factor Bt, its presence denoting bluntness, its 

 absence acute pods. 



18. Parchmented or Non-Parchmented, Smooth or Con- 

 stricted, Non-Edible or Edible Pods. 



The great majority of pea varieties have pods the inner lining 

 of which is tough, papery and membranous in both the mature and 

 immature state. The ripe or mature pods of these parchmented 

 varieties are very tough and generally do not crumple up in drying. 

 In the wild species this parchmented character is exceptionally well 

 developed while in a few cultivated varieties such as the thin-podded 

 Goldkonig, the parchment is comparatively inconspicuous, so that 

 the dry pods are slightly crumpled. None of these varieties are re- 

 garded as having edible pods. 



Differing conspicuously from these parchmented varieties are 



