1098 
Journal of Agricultural Research 
Vol. XXVIII, No. 11 
Table I .—Biometrical constants for Jala and Tom Thumb maize and their F x 
and F‘2 hybrid populations 
Character desig¬ 
nation 
Con¬ 
stants 
Jala 
Tom 
Thumb 
F, 
Fj with normal seed classes 
Fj with deficient seeds 
White 
seeds 
plant¬ 
ed 
Yellow 
seeds 
plant¬ 
ed 
Pale 
yellow 
seeds 
plant¬ 
ed 
Entire 
popu¬ 
lation 
White 
seeds 
plant¬ 
ed 
Yellow 
seeds 
plant¬ 
ed 
Entire 
popu¬ 
lation 
Height in dcm. 
Number of leaves 
above ear. 
Number of days to 
silk. 
Days pollen to silk. 
Weight of a single 
seed in grams. 
Length of ear in cm. 
Number of rows on 
ear. 
Diameter of stalk 
in mm. 
mean.... 
(T.. 
PE. 
mean_ 
a _ 
PE_ 
Mean... 
<T _ 
PE_ 
Mean... 
<r._. 
PE_ 
Mean... 
• <r .. 
PE_ 
Mean... 
a .. 
PE. 
Mean... 
<7.. 
PE_ 
Mean... 
< a _ 
PE.. 
52.75 
5.06 
• .30 
5.98 
.78 
.05 
124.7 
7. 44 
.44 
6.20 
2.88 
. 18 
.562 
.34 
.04 
2& 25 
5.54 
.30 
12.68 
1.74 
.10 
39.05 
4.27 
.25 
6.14 
1.46 
. 15 
3. 32 
1.63 
.17 
39.50 
2.52 
.28 
0.00 
1.89 
.23 
.064 
.02 
.003 
6.22 
1. 49 
.19 
11.80 
.69 
.10 
24. 80 
2.59 
.222 
4.41 
.53 
.045 
73.20 
3. 93 
.342 
1.91 
1. 91 
. 167 
.310 
.030 
.003 
20.00 
2.14 
.185 
14.05 
1.13 
.097 
28.16 
2.56 
.22 
21.86 
4.16 
.291 
3.98 
.84 
.059 
74.22 
5.17 
.360 
1.73 
2.26 
.160 
.28 
.05 
.004 
16.73 
2.79 
.191 
13.19 
1.78 
.122 
26.92 
5.47 
.375 
21. 20 
3.66 
.320 
3.85 
.87 
.076 
71.10 
7.34 
.639 
.88 
1. 33 
.114 
.28 
.03 
.003 
15.60 
2.33 
.230 
13.40 
1.24 
.108 
26.60 
5.38 
.469 
20.80 
4.15 
.204 
3.94 
.72 
.036 
72.50 
7.66 
.385 
1. 56 
2.55 
. 128 
.27 
.04 
.002 
16.50 
3. 21 
.161 
13.13 
1.64 
.083 
27.07 
5.70 
.281 
21.17 
4.06 
.147 
3.94 
.76 
.028 
72.73 
7.06 
.26 
1.49 
2.28 
.084 
.27 
.05 
.002 
16.42 
2.73 
.100 
13.19 
1.62 
.060 
26.95 
5. 50 
.200 
22.80 
4. 59 
.632 
4.50 
.64 
.089 
77.80 
10.17 
1. 39 
1. 50 
1.68 
.231 
.25 
.07 
.01 
18.20 
3. 37 
.463 
13.20 
1.45 
.199 
27.00 
5.08 
.70 
21.10 
3. 92 
.542 
4.48 
.91 
.091 
74.31 
6. 74 
.673 
2.04 
3. 21 
.322 
.25 
.04 
.005 
17.79 
2.80 
.29 
12.80 
1.56 
.16 
25.26 
4. 37 
.44 
21. 69 
4.20 
.34 
4. 49 
.79 
.064 
75.52 
8.26 
.67 
1. 86 
2.78 
.226 
.25 
.05 
.004 
17.94 
3. 01 
.248 
12.93 
1.67 
.139 
25.88 
4.60 
.374 
Fig. 4—Frequency distributions for weight of seed. Estimated factorial difference between parents 19 
By use of Castle’s formula as improved by Wright 7 for estimating the factorial 
difference in the case of each character, it is seen that the least number of factors 
involved for the four characters, days to silk, height of plant, length of ear, and 
weight of seed, is with the character, length of ear, where the formula indicates a 
difference of 17-18 factors between the two parents, while 28 factors are indicated 
for height of plant. 
While too much emphasis should not be placed upon this method of estimating 
the number of heritable factors involved, it is believed that the method under¬ 
estimates rather than exaggerates the actual number. This would seem to follow 
7 Castle, W. E. An improved method of estimating the number of genetic factors concerned 
in cases of blending inheritance. Science 54: 223. 1921. 
