506 WHITE— STUDIES OF INHERITANCE IN PISUM. 



in my experience, turn brown or red. The red can be eliminated by 

 boiling, which will leave the seeds thus treated gray (i). Gray 

 chemically (55) is determined by a greenish pigment contained in 

 all or almost all the seed coat cells. With but three or four possible 

 exceptions, all colored flowered varieties have seeds with gray pig- 

 ment. 



Orange brozvn or light yellow orange seed coat color is charac- 

 teristic of several varieties of field peas with colored flowers de- 

 scribed by Tschermak (86) as P. arvense nos. VI., IX. and X. With 

 age and exposure, they turn browner. 



Dark brozvn seed coat is a dark chocolate brown typical of the 

 red-flowered Kneifel pea with purple pods experimented with by 

 Tschermalv (86) and Haage and Schmidt's Kapuziner. 



Violet or dark purple seed coats are of two different kinds, one 

 apparently what Emerson (27.5) would call a recurring mutation, 

 which results from an extreme variation of the purple spot pattern 

 to a self-purple and the subsequent breeding true of them (34). 

 The other type of purple seed coat is a constant characteristic of sev- 

 eral varieties of field peas, particularly of No. 24894 (29), the " black 

 Abyssinian " pea of the U. S. Department of Agriculture. The 

 genetics of the first type is taken up under the seed coat color pat- 

 terns of Pisum. That of the latter type is only mentioned, so far 

 as I am aware, in Vilmorin's list (90) where it is recorded as a 

 dominant to various other seed coat colors. 



The seed coat patterns of Pisum are three in number — a purple 

 stippling or dotting, a brown marbling, and an eye pattern. 



Purple dotting or stippling is only found in association with races 

 with colored flowers and gray seed coats, although many colored- 

 flowered varieties do not have seeds with purple dots. The dots 

 themselves often transgress the limits of dots, resulting in splotches 

 and, in extreme cases, wholly self-colored peas (i, 22, 34, 81, 

 86). In the seeds with gray seed coats which have turned red or 

 brownish, the purple dots are often obliterated (i-). The purple 

 color according to Lock (55, 56) is a cell-sap pigment, confined 

 to certain large cells of the sub-epidermal layer. This fact accounts 

 for its diffusion into blotches and traces and its complete oblitera- 

 tion when the seeds are left exposed to damp, sunshiny weather 



