366 
Journal of Agricultural Reserach 
Vol.XIV, No. 9 
pulled, the upper portion was wrapped securely in paper to obviate any 
shattering. The plants were then hung in the laboratory to dry. 
Data were taken on the seedlings and on the mature plants as shown 
in Table II. The whole plant was the unit used in making the determina¬ 
tions. The total weight of the plant was determined after the root had 
been severed at the surface of the ground and discarded. The weight of 
the seed was subtracted from the total weight of the plant for the straw 
weight determinations. Height of tallest culm was determined by meas¬ 
uring the primary stem from its attachment to the root to the tip of the 
apical spikelet. The average length of culms, including spikes, and of 
spikes only, per plant, was determined successively by laying them care¬ 
fully end to end and taking their respective measurements. Then the 
total length divided by the number gave the average length of culms 
and spikes, respectively. Determinations were made on a total of 2,048 
plants: 300 in 1914, 571 in 1915, 698 in 1916, and 479 in 1917. All 
determinations have been checked. 
EFFECT OF ENVIRONMENT DURING GROWTH 
In Table II are given the means, standard deviations, and coefficients 
of variability, with their respective probable errors, for each of the char¬ 
acters studied. The seed for the 1914 and 1915 planting was selected 
from the 1913 crop and for the two years had approximately equal mean 
weights and standard deviations. The seed planted in 1916 and 1917 was 
selected from the crop grown in 1915 and 1916, respectively. The mean 
weight of the seed planted in 1916 was 7.254^0.345 mgm. lower and 
that for 1917, 14.019±0.352 mgm. lower than the mean weight of the 
seed used the two previous years. 1 * 
Table II.— Means , standard deviations , and coefficients of variability for the characters 
of the wheat studied 
Means. 
Characters studied. 
Weight of individual seeds planted, 
mgm.. 
Number of days from planting to second 
leaf.. 
Height of plants at appearance of sec¬ 
ond leaf....cm. 
Height of plants at six weeks.cm. 
Height of tallest culm at maturity.. cm. 
Average height of culms at maturity, 
cm... 
Average length of spikes per plant, .cm. 
Total length of culms per plant_cm. 
Total length of spikes per plant_cm. 
Number of culms per plant. 
Total yield per plant.dgm. 
Yield of straw per plant.dgm. 
Yield of kernels per plant.dgm. 
Number of kernels per plant... 
Average weight of kernels per plant, 
mgm... 
1914 
1915 
1916 
1917 
32. 580*0. 393 
33* 033±0. 260 
25, 779*0. 226 
13. 769^ .049 
19. 014*0. 237 
26. 373 * .041 
6.401 ± .044 
22. 525* . 150 
87.021 ± .389 
5*286* .039 
, 23. 277± . no 
113.663±. 173 
5*35*± *024 
18. 515* .076 
91.043* .149 
6. 247 ± .251 
15. 638± . 641 
98. 763 ± ■ 193 
68. 833 ± .460 
7*638* .039 
248. 000*4. 483 
24. 333 ± .423 
3. 606 * . 063 
47- 4°o± 1. 049 
39. 600± . 894 
8. I53± • 209 
55.86o±i. 081 
98. 419* . 27a 
8. 33 ■ 029 
686. 821 ± 5. 220 
54- 461 * .451 
6.977± *053 
135. 617± 1. 250 
94. 603 * .832 
40. 5I2± .466 
142. 629* 1. 428 
84. 693 ± • iS9 
7. 985 ± .018 
625. 043 ± 1. 740 
20. 62 7 ± . 163 
2.651* .019 
48. 022± .391 
30. 644± .245 
17* 305 ± *144 
69*183* -549 
94* 483 ± • 208 
8- O32* .020 
268. 966 ±2. 026 
23. 601* . 177 
2. 847 * .020 
66. 5S8± .577 
41. 299db -357 
26. 007* . 227 
75. 087 * .648 
14. 86o± . 156 
27*5 6 3± ■ Ji8 
23* 732* • 056 
34-050* .057 
1 The probable error of a difference is found by extracting the square root of the sum of the squares of 
the probable errors of the two numbers. 
