520 WHITE— STUDIES OF INHERITANCE IN PISUM. 



in crosses with yellow cotyledon varieties if demonstration material 

 for illustrating Mendel's law is desired. Lock found that green 

 seeds exposed to light in a dry bottle for a length of time faded and 

 became yellowish. Mendel and Tschermak both found that injury 

 from the pea-weevil would produce yellowish blotches and even 

 wholly yellow seeds. Such greens as Laxton's Alpha will always 

 give some piebald and even some yellow seeds if the pods are left 

 on the vines till they are all ripe (i). Piebald peas remain green 

 if kept in the dark, and a dry place, but fade on the exposed surface 

 on exposure to light. Piebald seeds of one pod are all tinged on the 

 same surface. Tinged seeds of dark green types or varieties nor- 

 mally giving no piebalds are less viable than piebald peas of green- 

 seeded varieties (i). Numerous selection experiments were made 

 by Bateson (i) but tinged or piebald seeds produced no more seeds 

 like themselves than did normal green seeds. 



Telephone seed of all types retains its series of color gradations. 

 Some varieties of peas such as Sutton's Nonpareil (i) are heterozy- 

 gous for cotyledon color and of course these statements do not apply 

 to them. 



Yclloiv Cotyledon. — Yellow cotyledon color varies from light 

 yellows and yellowish greens to deep orange-yellow, such as is 

 characteristic of Spate Gold, and, as in the case of the greens, this 

 color shading is a varietal characteristic, some varieties having light 

 yellow peas and no other shade, c. g., Goldkonig and P. humile of 

 Sutton. The yellow color may remain somewhat greenish if the 

 pods are not properly matured and certain varieties are extremely 

 particular in this respect. Spate Gold is a dark green pea when 

 immature but changes very rapidly to bright deep orange-yellow 

 when mature. Even after the pods have the appearance of maturity 

 and are dry, the change sometimes has not resulted. Improper 

 maturing due to lack of sufficient light and in some cases to an over- 

 supply of moisture is the usual cause of ununiform coloring in yellow 

 peas. According to Bunyard (21, p. 131) both yellow and green 

 cotyledon varieties have yellow and green pigment in their immature 

 seeds, but the yellow cotyledon varieties possess an additional 

 hereditary substance — an enzyme perhaps, which causes the green 

 pigment to fade when the seeds mature. Green when present is 



