io8 
Journal of Agricultural Research 
Vol. XI, No. 4 
rect effects of selection as shown in the crop of 1905, after selection for 
chemical composition had been made since 1897* It was there shown that 
the four strains exhibit some significant differences with respect to physi¬ 
cal characters of ears.' As we have measured each ear of a fair-sized 
random sample of ears from each strain for crops grown from 1905-1915, 
we are now in a position to determine whether the differences existing in 
1905 have persisted pretty regularly under changed conditions of soil and 
season, or if some further indirect influence of the selection for chemical 
composition is to be noted in considering the four physical characters on 
which we have collected data. Table II gives the means, empirical 
modes, standard deviations, and coefficients of variability of the length 
of ears, the circumference of ears, the weight of ears, and the number of 
rows of kernels on ears, for each of the four strains bred for chemical 
composition, for the 11 crops from 1905 to 1915, inclusive. 
TabIvE II. —Type and variability of the four chemical-composition strains of Indian corn 
for 11 crops, 190$ to 191 5 
CROP OP 1905 
Character and strain. 
Mean. 
Em¬ 
pirical 
mode. 
Standard devia¬ 
tion. 
Coefficient of vari¬ 
ability. 
Length of ear, in inches: 
17. 6±o. 4 
High-protein.. 
7. 2I±0. 04 
7-5 
1. 27±0. 03 
Low-protein. 
7. 8o± . 04 
8.5 
1. 54 ± . 03 
19. 7 ± .4 
High-oil. 
6. 87 ± .04 
7.0 
i- 39 ± • °3 
20. 2 ± .4 
Low-oil. 
7. 48± .04 
8. 0 
1. 3 <>± .03 
17. 4 ± -4 
Circumference of ear, in 
inches: 
7. 6± .2 
High-protein. 
5 - 7 r ± - 0I 
5*7 
• 44 ± -oi 
Low-protein. 
6. 5i± .02 
6-3 
. 61 ± .01 
9. 4 ± .2 
High-oil. 
6. 05 ± .01 
6.3 
• 53 i - OI 
8.8± .2 
Low-oil. 
6. 65 ± .02 
6.9 
• 59 ± - 0I 
8. 9± .2 
Weight of ear, in ounces: 
8. 0 
2. so± .03 
33 - 2± .4 
High-protein. 
7 * 53 ± -04 
Low-protein. 
9. 66± . 10 
10. 0 
3 * 3 °± * °7 
34 - 2± .7 
High-oil. 
7. 79 ± .07 
9.0 
2 . 43 ± • °5 
31. 2± .6 
Low-oil. 
9 * &4± . 08 
11. 0 
2. 87 ± . 06 
29. 2± . 7 
Rows of kernels on ears: 
1. 85± . 02 
High-protein. 
13. 72± .03 
14. 0 
13 - 5 ± -2 
Low-protein. 
14. 71 ± .06 
14. 0 
1. 94 ± *04 
13 - 7 ± -3 
High-oil. 
15.651b .06 
16. 0 
2. o8± . 04 
i 3 - 3 ± -3 
Low-oil. 
12. 8o± . 05 
12. 0 
1. 77± .04 
13-8± -3 
