98 R. A. EMERSON 
color phenotypes resulting from seeds with colored aleurone and those | 
from seeds with colorless aleurone. The F2 progeny came from a plant | 
that produced from self-pollination colored and colorless seeds in the | 
relation 60:24. This close approach to a 3:1 ratio indicates that the. 
F, plant could have been heterozygous for only one of the aleurone-factor | 
pairs A a, Cc, or Rr (Emerson, 1918). A cross with a C tester, Ac R, | 
resulted in 43 colored and no colorless seeds, while a cross with an R 
tester, A Cr, gave 46 colored and 32 colorless seeds, thus indicating Rr 
as the factor pair concerned. The colorless seeds must therefore have 
been rr, presumably 7’ r’, and in accordance with the hypothesis under 
test should have produced no green plants. Some of the colored seeds, 
on the contrary, should have been RR, supposedly Rk’ R’, and these 
should have given green plants. For the most part, the colored and the 
colorless seeds were planted separately. The 9:3:4 relation of the three 
plant-color types is theoretically made up of a 6:2:4 relation from colored 
seeds and a 3:1:0 relation from colorless seeds. Actually, from colorless 
seeds there appeared dilute purple and dilute sun red plants in the ratio 
69:15. The deviation from expectation, 6.0 + 2.7, might be expected to 
occur about once in seven trials, P equaling 0.14. From colored seeds 
the deviation from the theoretical distribution was such as might occur | 
thru errors of random sampling almost once in four trials, P equaling | 
0.23. The comparison follows: | 
Dilute Dilute 
Color types Green Total | 
purple sun red 
Illa IVa Illg, IVg 
Observedic se se eee 92 42 70 204 
@alculatedterc Geren one ee 102 34 68 204 
Ditkerence: =a es oe ee —10 +8 +2 0 
Aleurone is in some cases self-colored and in some cases mottled. 
Mottled aleurone ordinarily occurs only when the R factor is heterozygous, 
but not all heterozygous individuals are mottled (Emerson, 1918). 
Mottled seeds of the cross under discussion, just as colorless ones, since 
they are presumably R’7", should produce no green plants. In the 
case of some of the progenies noted above, the colored seeds were sorted 
into self-colored, mottled, and colorless. Since usually about one-third | 
