1096 
Journal of Agricultural Research 
Vol. XXVIll, No. J1 
/OO 
smallest type of normal maize. The gigantic parent used is a variety of maize 
from the west coast of Mexico, designated Jala. 6 Ears and seeds of both varieties 
are shown in Plate 1 and the relative differ¬ 
ences in size between them are shown dia- 
grammatically in figure 1. 
The cross was made with the large variety 
as the female parent and a small Fj popula¬ 
tion was grown at Lanham, Md. From 
this Fi population two self-pollinated ears 
were chosen to provide the F 2 generation. 
One of these ears was perfectly normal with 
yellow, light yellow, and white seeds in the 
proportion of 1-2-1 (100 yellow', 246 light 
yellow, 119 white) wiiile the other had but 
two seed classes, yellow and white in approxi¬ 
mately equal numbers (170 white, 163 yellow) 
'with a large proportion of deficient seeds con¬ 
sisting of hardly more than a pericarp. Since 
the Tom Thumb parent has a yellow endo¬ 
sperm and that of the Jala parent is white it 
was thought possible that the large propor¬ 
tion of deficient seeds represented some in¬ 
compatibilities in recombinations. 
These F 2 populations together with prog¬ 
enies of both parents and the remainder of 
the Fi seed were grown at Chula Vista, Calif., 
where the moderate climate and long grow¬ 
ing season permitted the latest segregates 
and parents to mature normally. 
In view r of the absence of light yellow seeds 
on one ear, together with the high propor¬ 
tion of sterile ovularies, the several seed 
classes were grown separately. This proved 
to be a needless precaution, as there were 
no outstanding differences between the two 
F 2 populations nor in the several seed classes, 
as is shown by the biometrical constants in 
Table I. In analyzing the correlations, 
however, only one F 2 population w r as used, 
namely, that not having the complication of 
deficient seeds. The correlations w r ere cal¬ 
culated separately for each seed class but 
since there were no significant differences 
between the classes only the coefficients for 
the entire population are presented. 
ft $ & « « 
Fig. 1.— Diagrammatic representation of the 
differences between Jala and Tom Thumb 
maize. Jala taken as 100 
6 Kemptox, J. H. Jala, a LARGE variety of corn from MEXICO. Jour. Heredity 15 .337-314. 192!. 
