WHITE— STUDIES OF INHERITANCE IN PISUM. 551 



non-colored axils, crossed with either colored flower, non-colored 

 axil segregates or with the pure ancestral colored flower, non-col- 

 ored axil variety always gave progeny with no color in their axils. 

 White flowered races crossed with each other never have given 

 progeny with colored axils. 



Interpretation. 



All the data so far obtained indicate that color in the leaf axils, 

 pinnae, and stem base are explainable on a two factor basis, one of 

 the factors (C) being absolutely coupled with the pink pigment 

 flower factor (A). The other factor (D) is inherited independently 

 of A or of any other factor so far as our present data go. Since 

 A and C are absolutely coupled, it is simpler to consider them both 

 as one factor (A). Regarded thus, colored axils result from the 

 joint activity of A and D. In the absence of D, the plant will have 

 no axil color, though the flowers and seed coats may be colored or 

 non-colored (white). The factor D may be present in varieties 

 with colored flowers or varieties with white flowers. Interpreted 

 in this manner, all the above data are simply explained and all the 

 various combinations mentioned may be obtained. The formulae 

 for the various varieties of peas would then be : 



1. Colored flowers, colored axils -[ ^^^^RJ?. 



' [ AABBDD 



2. Colored flowers, non-colored axils - V"V"^^j , 



( AABBdd 



3. White flowers, non-colored axils -[ ^^55?P 

 ^ ( aaBBdd 



Tschermak (86) has given the formulas for 7 varieties with col- 

 ored flowers and 5 varieties with white flowers. All the white- 

 flowered varieties so far experimented with are aaBBDD, the 

 aaBBdd class being represented only by Tschermak's true-breeding 

 segregates from crosses of 2 X 3- 



9. Flower Color. 



Flower colors in all the cultivated varieties and species of peas 

 are easily separated into three sharply defined classes, between which 

 there are no intergrades. These color classes are white, salmon 



