18 Influence of Weight of Seed on Plant 
the mean number of pods may not increase at the same rate from the lowest to 
the highest, the lightest to the heaviest, grade of seeds. Practically speaking they 
may be considered to do so. 
The coefficients of correlation are rather small, ranging from about '120 to 
•280. The average of the twenty series is -1615. It may be noted, however, that 
they are in every instance positive, thus indicating that the selection of larger 
seeds will give a somewhat higher yield of pods. 
The second term of the regression equation enables us to read off at once the 
increase in the number of pods per plant to be secured by selecting seeds one unit 
(i.e. 25 mg.) or more above the average. These values range widely, as is to be 
expected from the fact that the crops upon which they were calculated were pur- 
posely grown under most diverse cultural conditions. The slopes of the regression 
lines will make clear to the eye the advantages to be secured by planting heavier 
seed. 
Cold Spring Harbor, U.S.A., 
January 29, 1912. 
TABLE I. 
Pods per Plant. 
Series 
Total 
Plants 
Mean and 
Probable Error 
Standard Deviation 
and 
Probable Error 
Coefficient of Variation 
and 
Probable Error 
NHH 
1484 
16-99+ '15 
8-67+ -11 
51-02 + 0-78 
NHHH ... 
1271 
11-93+ -10 
5-17+ -07 
43-29 + 0-68 
NHD 
1416 
3-97+ -03 
1-94+ -02 
48-97+0-76 
NHDD ... 
1204 
4-58+ -05 
2-38+ -03 
51-84 + 0-88 
NDD 
513 
3 -59 ±-06 
1-89+ -04 
52-66 + 1-38 
NDDD ... 
459 
4-41+ -06 
1 -93 + -04 
43-86 + 1-15 
NDH 
670 
14-62+ -21 
8-24+ -15 
56-39+1-33 
NDHH ... 
565 
11-83+ -14 
4-96+ -10 
41-94 + 0-98 
FSS 
868 
15-03+ -17 
7-41± -12 
49-34 + 0-97 
FSG 
586 
14-22+ -21 
7-38+ -15 
51-90+1-27 
FSH 
475 
17-29+ -25 
7-94+-17 
45-89+1-20 
FSHH ... 
429 
11-84+ -16 
4-80+ -11 
40-50 + 1-08 
FSD 
428 
3-43+ -06 
1 -69 + -04 
49-42 + 1-39 
FSDD ... 
387 
4-04+ -06 
1-73 + '04 
42-85 + 1-22 
uss 
680 
15-74+ -16 
6-04+ -11 
38-37 ±0-80 
use 
530 
10-14+ -13 
4-38+ -09 
43-23+1-05 
USH 
361 
14-04+ -20 
5-55+ -14 
39-56 + 1-14 
USHH ... 
224 
8-44± -15 
3-24+ -10 
38-45 + 1-25 
USD 
312 
2-59+ -05 
1 -23 + -03 
47-30 + 1-54 
USDD ... 
237 
3-62+ -09 
2-10+ -07 
57-97 + 2-32 
