WHITE— STUDIES OF INHERITANCE IN PISUM. 531 



however, often have smooth seeds and it is to be inferred from 

 Tschermak's data and formulas (86) that in crosses of round 

 smooth, white flowers with round smooth, colored flowers, the F^ 

 generation consists of three classes — indent, colored flowers ; round 

 smooth, colored flowers ; round smooth, white flowers. As regards 

 the seed characters, only two classes are present — indent and smooth. 

 From crosses of four round-seeded, colored-flower varieties with 

 five round-seeded, white-flowered varieties, Tschermak (86) se- 

 cured in Fo : 



i8i indent : 96 smooth or 1.89:1. 



In F3 part of the indent and part of the smooth seeds bred true, 

 \vhile a part of each class again gave both indent and smooth seeds. 

 From this and other data of Tschermak's one may consider the 

 above F2 numbers as a very poor approximation to a 9:7 ratio — 

 the actual results expected had the approximation been perfect be- 

 ing 155.7 indent: 121. i smooth. 



Round smooth, white flozvers X indent, colored flowers in F^ (of 

 cotyledons) always gives round smooth seeds, while the F^ of the 

 reciprocal cross, where the maternal parent has colored flowers, con- 

 sists of indent seeds (Tschermak 80, 81), [(Correns), Bateson 3]. 

 The Fj of seed coats (F^ of cotyledons) consists entirely of indent 

 seeds and colored flowers, while in Fo of seed coats (F3 of cotyle- 

 dons) indents and colored flowers to round smooth and white flowers 

 occur in a ratio approximating 3 indent : i round smooth. The 

 above description of the facts applies to all but one cross of this type. 

 In this exceptional case, the round smooth white-flowered Nain de 

 Bretagne was the pollen parent in a cross with an indent variety. 

 The F-^ was indent, as usual, but the F^ of seed coats (F2 of 

 cotyledons), instead of giving all indent seeds, as is commonly the 

 case, gave quite definitely indents and rounds in the ratio of 3:1. 

 Three such F^ plants gave 339 indent, 119 round smooth, and 39 

 uncertain or of an intermediate type. Further, one F„ plant appar- 

 ently grown from the round seeds had only round seeds with colored 

 seed coats (F, of seed coats, F3 of cotyledons) (Bateson 3, p. 262). 



Round smooth, ivhite floivers X wrinkled, white flowers give in 

 F^ (of cotyledons), all round smooth seeds, which in F„ give ap- 



PROC. AMF.R. PHIL. SOC, VOL. LVI, 11, DECEMBER II, I917. 



