398 ORLAND E. WHITE 
Table 2 
Segregation of Endosperm Color in Maize 
Cross 
Yellow 
White 
Total 
Ratios Act. Obt. 
Ratios Theor. 
Exp. 
F2 generation of white X yellow or 
reciprocal or data on hybrid popu- 
lation of same character 
F2 generation of white X light yellow 
or reciprocal or data on hybrid 
F2 generation of white X dark yellow 
or reciprocal or data on hybrid 
population of same character. . . . 
9458 
6,792 
2,376 
466 
2,428 
766 
9,924 
9,220 
3,142 
95.1: 4.9 
73.7:26.3 
75-7:24-3 
93-8:6.2 
(15:1) 
75:25 
75:25 
F2 generation of white X yellow 
Expected 
609 dark yellow: 1, 143 light yellow: 589 
white 
585.2 darkyellow:i,i70.4 light yellow: 585.2 
white 
The varieties studied by Burtt-Davy (i) apparently consisted of 
two distinct yellow types — a dark and a light, each of which with its 
''opposite" represented an independent allelomorphic pair. The 
darker of these yellows gives a i : 2 : i ratio, while ''the other (the 
paler) gives the ratio 9:3:3:1." The writer is at a loss to under- 
stand the meaning of the above quoted statement, unless the two 
yellows were crossed together and gave in addition to three types of 
yellow, whites in the ratio of i W : 15 Y. If each yellow is repre- 
sented by an independent factor, crosses with white should give in 
each case in F2 only i : 2 : i or 3 : i ratios. This pale yellow has 
sometimes been mistaken for a "dominant white." Burtt-Davy found 
ten shades of yellow in the F3 seed generation from crossing yellows 
with whites. Further, Burtt-Davy (p. 172, 173, 177, 188) refers to 
a yellow endosperm color, which depends for its expression on the 
presence of two factors — a color factor and a pigment factor. In 
absence of either, the endosperm will be white, and by crossing two 
white races, each carrying one of the factors, the resulting progeny 
will all have yellow endosperm. 
Emerson (8) obtained from F2 populations of crosses of the orange 
yellow Queen's Golden with Black Mexican (white endosperm), two 
yellow endosperm colors (a dark and a pale) in addition to the expected 
orange and white endosperm segregates, and in F3, some of the pale 
yellow segregates bred true, while others gave 3 pale yellow : i white. 
