Oct. 22, 1917 Indirect Effects of Selections in Breeding Indian Corn 139 
Table IV .—Type and variability of the erect - and declining-ear strains of Indian 
corn —Continued 
CROP OE 1916 
Character and strain. 
Mean. 
Empir¬ 
ical 
mode. 
Standard devia¬ 
tion. 
Coefficient of varia¬ 
bility. 
Length of ear, in inches: 
Erect ears. 
6. 985 ±0. 041 
7.0 
1. 29o±o. 029 
18. 47 ±0. 43 
Declining ears. 
7. 6391b .034 
7-5 
1.1411k . 024 
14 - 94±o. 32 
Circumference of ear, in 
inches: 
Erect ears. 
4. 892 ± .014 
S-o 
. 4091k . 010 
8. 37±o. 20 
Declining ears. 
5* 599 ± *013 
5 - 5 
. 438 db .009 
7.82 ±0.17 
Weight of ear, in ounces: 
Erect ears. 
5-0191k -061 
5 -° 
i. 459 ± -043 
29.07±i. 25 
Declining ears. 
Rows of kernels on ears: 
6 . 1781k . 048 
7.0 
i. 4*7 ± .034 
22. 78±o. 57 
Erect ears. 
IS- 573 ± -072 
14.0 
1.679 ± .051 
11. S 2 ±0.35 
Declining ears. 
i5-420± .059 
16.0 
1. 7 6 7 ± -059 
11. 46db0. 27 
HIGH- AND LOW-EAR STRAINS 
Table V gives the means, standard deviations, coefficients of variability, 
and corresponding probable errors for the characters in question of the 
high- and low-ear strains. 
DIFFERENCES IN MEANS 
[Fig. 17 to 20J 
The mean lengths of ears of the low-ear strain exceed in general slightly 
but significantly the mean lengths of ears of the high-ear strain, but 
there are two exceptions in nine years. The mean circumference of ears 
from the low-ear strain exceeds decidedly in each year the mean circum¬ 
ference of ears of the high-ear strain. The mean weight of ears of the 
low-ear strain exceeds the mean weight of the high-ear strain in seven 
of the nine years. Some of these differences would be regarded as unques¬ 
tionably significant in the light of their probable errors, but the excess of 
the mean weights of low ears is not so well fixed but that in two seasons 
of the nine the mean weights of high ears exceed slightly those of the 
low ears. In mean number of rows of kernels on ears the low ears exceed 
the high ears in every case. This difference is decidedly significant. 
DIFFERENCES IN VARIABILITY 
[Fig. 21 to 24] 
In length of ears it is doubtful if there is any significant difference in 
variability between the high- and low-ear strains. In circumference of 
ears the low-ear strain shows in general the greater variability. In 
weight of ears it is doubtful whether there is any si gnific ant difference 
7768°—17 - i 
