INHERITANCE OF ENDOSPERM COLOR IN MAIZE 397 
Table i 
Ratios 
Cross 
Yellow 
White 
Total 
Ratios Act, Obt. 
Theor. 
Exp. 
Yellow heterozygoteX white homo- 
zygote (F2) . 
1,963 
1,982 
3,945 
49.6 :50.4 
50:50 
Yellow heterozygoteX pure white 
variety 
26,792 
26,751 
53,543 
50.03:49.97 
50:50 
White variety (homozygote) Xyel- 
2,723 
2,846 
5,569 
48 :52 
50:50 * 
Totals 
31,478 
31,579 
63,057 
49.6 .-50.4 
50:50 
F2 white segregate X pure white 
59 all white ears 
all 
Yellow heterozygote (selfed) 
16,592 
5,681 
22,273 
74-5 :25-5 
75:25 
Sperm varieties, as an independent allelomorphic pair. In the va- 
rieties studied by East and Hayes, the two yellows were indistinguish- 
able except that ears in which both were present in homozygous con- 
dition were usually darker than ears homozygous for either one of the 
yellows alone. Apparently either of the yellows, even in a homozygous 
condition, could not be distinguished from the other, but, when both 
were present in crosses with non-yellow races, the F2 ratio approxi- 
mated 15 Y : I W. Designating the two factors as Yi and Y2, the 
presence of either produced a similar effect. In some crosses, domi- 
nance of yellow was complete and heterozygotes were indistinguishable, 
while, in other crosses, as many as five shades of yellow were present 
among the F2 progeny, each shade signifying a difference in factorial 
composition from darker to light in the following order: Y1Y1Y2Y2, 
YiYiy2y2 or yiyiY2Y2, YiyiY2y2, YiyiY2Y2 or YiYiy2Y2, Yiyiy2y2 or 
yiyiy2Y2. In Table 17, p. 56 (7) East and Hayes refer to an F2 
population from white X yellow endosperm which gives only a 3Y:iW 
ratio, but two shades of 3^ellow are distinguishable — a dark and light 
in the ratio of i : 2. This is interpreted as a i : 2 : i monohybrid 
ratio in which the heterozygote is easily distinguished, owing to 
imperfect dominance. The nature of the starch, whether soft (flour) 
or horny (corneous), also causes a variation in the intensity of the 
yellow endosperm color. From certain crosses, in a few cases, ap- 
parently white segregate seeds, when planted, gave either pure yellow 
or 3 Y : I W progeny. 
East and Hayes's data are partially summarized in Table 2 : 
