62 
The original variety from which we obtained the P32 type foliage 
and pod character is Wachs Schwert and it is very probably the 
yellow pod type which Gregor Mendel worked with and listed 
among his seven pairs. 
Crosses between all these types in all possible combinations 
have been made. The junior author worked out the inheritance 
of the foliage and pod colors and their relation to each other in 
fulfillment of the thesis requirement in botany for an M.S. degree 
in Columbia University. The genetic factors involved are: 
ordinary green foliage and the green foliage of P32 type, O; 
P34 type, 0,; P30 type, 0,. Green is dominant to both yellows. 
P30 type in a sense is dominant to P34 type. The three types 
form an allelomorphic series. The pod colors are designated 
Gp and ‘gp. The expression of the foliage factors modifies the 
—— 
expression of Gp in types P30 and P34, changing the pod colors 
to yellow. Combinations of gp and 0, and 0, have been obtained, 
so gp is not to be regarded as always associated with green 
foliage O. 
As to the cotyledon factors, the recessive foliage color oy is 
very closely linked with the dominant yellow cotyledon color 
factor J, the cross-overs being very rare and less than five per 
cent. Conversely O is linked with 7. The cross green foliage, 
green cotyledon X yellow foliage P34 type, yellow cotyledon, 
hence gives a segregate class—green foliage, yellow cotyledons— 
that is very nearly always a dihybrid heterozygote. At first 
the results from this cross were believed to represent a mono- 
factorial difference, the yellow foliage and yellow cotyledons, 
green foliage and green cotyledons respectively being regarded 
as expressions of the same factors in different parts of the plants. 
On this basis, the green foliage, yellow cotyledon varieties would 
be regarded as a third member type of an allelomorphic series, 
either the yellow cotyledon type (J7GG) or the green cotyledon 
type (GG) representing a mutation from the other. That this 
is not the true explanation has been shown by the discovery of 
the cross-over classes noted above, 0,iG and OIG. 
The relations of the factors of the P30 type to the others are 
very complicated. Owing to the difficulty of distinguishing in 
some cases between wrinkled yellow and wrinkled green coty- 
