The Inheritance of Quantitative Characters in Maize 11 
The actual results are so close to those expected on the theory 
that it would be a most wonderful coincidence if the theory were 
not correct. 
The original basis for the theory developed by East (1910) 
was of this same character. Two factors for the production of 
yellow color in the endosperm of maize were found. The pres- 
ence of either factor produced yellow seeds identical in appear- 
ance, but each was allelomorphic to its own absence in crosses. 
An ear with the zygotic formula Y 1 Y 1 was exactly like an ear 
with the zygotic formula Y 2 Y 2 . It is true that there was a cumu- 
lative effect so that ears with the zygotic formula Y 1 Y 1 Y 2 Y 2 were 
darker in color than those homozygous for a single factor, but 
those zygotes homozygous for either single factor were indis- 
tinguishable. A zygote from any cross which produced the con- 
stitution Y 1 y 1 Y 2 y 2 gave approximately 15 yellows : 1 white in the 
next generation when selfed. A total of 5,222 segregates were 
recorded, of which 4,880 were yellow and 342 white. This ratio 
is very nearly 15 : 1, the closest possible ratio being 4.895 : 327. 
The actual results were therefore astonishingly close to theo- 
retical expectation. 
These segregates were followed to the F 3 generation, and gave 
decisive evidence that they varied in zygotic constitution in accord- 
ance with the scheme which has just been outlined. Theoretically 
the 15 yellows of F 2 should have the following zygotic formulae : 
Each of these classes provided for by the theory were actually 
obtained. Those ears having the formula Y ^Y^y 2 y 2 were indis- 
tinguishable from those ears having the formula" ysjJfJ?.,, but 
where Y 1 Y 1 and Y 2 Y 2 were both present in the same zygote the 
seeds were a much darker yellow than where either yellow alone 
was present. 
It should be noted that Emerson (1911) has found two yellow 
colors in the endosperm of maize that seem to be unlike in 
appearance. One is a golden yellow and one a light yellow. It 
is possible that further observations will show that the orange 
yellow is due to the cumulative action of two similar or identical 
F 2 
f 1 Y X Y X Y 2 Y 2 
\ 2 YJ: x Y 2 y 2 
i 2 Y,i A Y 2 Y 2 
gives in 
F 3 
all yellow, 
all yellow, 
all yellow. 
15 yellow : 1 white. 
all yellow. 
3 yellow : 1 white. 
all yellow. 
3 vellow : 1 white. 
