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ledons (except under the most ideal environmental conditions) 
in crosses involving this type, the writers do not feel absolutely 
certain as yet regarding the validity of the linkage group o,g-OG 
(yellow foliage, yellow cotyledons-green foliage, green coty- 
ledons) discussed in ‘‘ Pisum studies, IV.” Both cross-over 
classes apparently have been obtained, but owing to the environ- 
mental complications, as well as others in connection with the 
modifying effect of the factor R (discussed in all three above- 
mentioned studies), more data are needed. When both R and 
0, are combined in the same plant with z and g, the cotyledons 
are green, as though G instead of g were present. From such a 
cross as green foliage, smooth green cotyledon (7iRRGGOO) 
X yellow foliage P30 type, wrinkled yellow cotyledon (dirrggo,o,) 
or its reciprocal, Fp segregate classes representing the expected 
yellow foliage, smooth yellow cotyledon and green foliage, 
smooth yellow cotyledon types were absent. The yellow foliage 
wrinkled green cotyledon type was also all but absent, there 
being but one among 575 Fs, segregates. The actual F, results 
obtained from a number of these crosses were: 0 G C0 
YFRYC : 4 + 3? GFWYC : 24 YFWYC : 319 + 1? GFRGC : 
119 + 5? YFRGC :99 GFWGC:1 YFWGC. In respect to 
cotyledon color and texture alone, this cross gave all smooth 
green Fy; and 438 + 6? RGC:100 WGC:0 RYC: 28 + 3? 
WYC in F:.- The expected but absent RYC individuals seem 
to have been added to the RGC class. Another type of cross 
in respect to cotyledon color and texture gave results as follows: 
smooth dominant yellow (ZRG) X wrinkled recessive yellow (zrg) 
gave all smooth yellow in F, and in F,;—7o :3 +2: 
WGC : 204 RYC : 100 WYC. The general nature of the results 
of these crosses as regards the cotyledon characters were men- 
tioned in a footnote in the senior author’s earliest study on Pisum 
(see Amer. Nat. 50: 540. 1916, also published as Brooklyn 
Botanic Garden Contributions, no. 10). 
The P32 type, in respect to pod color and its associated 
yellowish top foliage, is recessive to green foliage, green pod 
types, as well as to P34 and P30. This character will be referred 
to as ‘“‘schwert.”” So far as we are aware this is the only yellow 
pod variation of this type in peas. The P32 type in respect to 
cotyledon color and texture, foliage color and the ‘‘schwert”’ 
