PLANT CoLors IN MaIzE 59 
i a previous paper (Emerson, 1918) that the presence of three dominant 
factors, A, C, and R, is necessary for the development of aleurone color. 
It is assumed that the factor pair A.a for aleurone color is identical with the 
pair Aa for plant color. Some of the evidence on which this assumption 
is based may well be considered at this point in order to justify the 
use of the same symbols for both plant and aleurone color. After the 
identity of Aa has been established, certain relations of aleurone color 
to plant color can be used to check up some of the conclusions previously 
drawn with respect to the genetic interrelations of the several plant-color 
vypes. , 3 
It will be recalled that dilute sun red crossed with green gave dilute 
sun red in F,; and a 3:1 ratio of the two types in Fe (table 17, group 1, 
page 134), and that backcrosses of F; with green gave a 1:1 ratio (group 2). 
The F, seeds of these F; plants also exhibited a 3:1 relation — 424 colored 
and 127 colorless, deviation 10.8 + 6.9— thus showing that only one 
factor pair, Aa, Cc, or Rr, was heterozygous. The colorless seeds 
produced 98 green plants, and the colored ones produced 269 dilute sun 
reds and 1 weak plant, recorded as green, which died in the seedling 
stage. Obviously the factor that differentiates dilute sun red from green 
is the same as the one that in these cases differentiated the colored from 
the colorless seeds, or some factor very closely linked with it. Fortunately, 
F, plants closely related to the ones which when selfed showed the behavior 
noted above, were backcrossed with green, colorless-seeded A _ testers 
(Emerson, 1918). Of the resulting seeds 632 were colored and 590 were 
colorless, evidently a 1:1 relation — the deviation being 21 + 11.8 — 
showing that the I; plants were, with respect to aleurone color, Aa 
CCRR. The colored seeds gave rise to 357 dilute sun red plants and 
the colorless seeds to 358 green plants. Evidently, therefore, it is the 
Aa pair that differentiates dilute sun red from green. This is in support 
of the assumed genotypes A b pl and ab pl for dilute sun red and green, 
respectively. - 
The single progeny recorded in group 3 of table 9 (page 127) came 
from a plant known to be A a with respect to aleurone color and pro- 
ducing 130 colored and:41 colorless seeds. The 3:1 aleurone-color relation 
shows it to have been heterozygous in only one aleurone-color factor, 
and therefore AaCCRR. The colored seeds, ACR, produced 67 
purple plants, and the colorless ones, aC R, produced 21 brown plants. 
