570 



WHITE— STUDIES OF INHERITANCE IN PISUM. 



the so-called sugar peas. The pods of this group of varieties are 

 absolutely non-parchmented, and more tender, sweet and edible 

 than string beans. When unripe, the pods have a granular trans- 

 lucency and are crumpled and constricted, so that the peas as they 

 mature appear to be pushing out that part of the pod with w'hich 

 they are in contact. When dry, these pods shrink and become much 

 more constricted, and very brittle. As a green vegetable they are 

 very popular in continental Europe and in China. So far as known 

 no wald forms have this character, though cultivated varieties of it 

 are described as far back as our botanical records go. 



Varieties Studied. 



Parchmented. — See Tschermak (8i, 86), Darbishire, Bateson 

 (i, 3), Lock (54) and others (89, 99).. 



Non-parchmentcd. — Wachs Schwert, French Gray Sugar, Petit 

 Pois, Dwarf French Gray Sugar, Giant Sugar (pods up to 11.25 

 cm. long). 



Results from Crossing. 



Parchmented X parchmented always gives parchmented in F^ 

 and succeeding generations. 



Parchmented X non-parchmented in most cases gives complete 

 dominance of parchment in F^ (60, 86, 89, 90). In other cases, dif- 

 ferent varieties being used, the F^ has been more or less intermedi- 

 ate, i. e., parchmented but not as heavily as in the parchmented 

 parent (i, 56). 



In Fo, the proportion of plants with either fully parchmented or 

 with more or less parchmented pods to those with complete absence 

 of parchment in their pods approximate 3:1. The following re- 

 sults have been obtained : 



