506 
Journal of Agricultural Research 
Vol. VII, No. xa 
the plants. 1 This is evident from a comparison of the weights of plants 
13 to 24, with 37 to 48, and of plants 25 to 36 with 49 to 60. 
Table I .—Comparative weights of rice plants grown in double flasks with ferrous sulphate 
* in acid and neutral solutions and percentage of nitrogen and iron 
Nutrient solution in flask— 
A, 
B. 
Neutral. . . . 
Acid. 
Do. 
Acid-f-iron... 
Neutral+ 
iron. 
Acid. 
Acid-}-iron.. 
Acid+iron... 
Neutral-f 
Neutral 4* 
iron. 
iron. 
Flasks 
No. 
1-4 
5 
9-12 
13-16 
17-20 
21-24 
25-28 
29-32 
33-36 
37-40 
41-44 
45-48 
49-52 
53-56 
57-6o 
Green 
weight 
of 
stalks 
and 
leaves. 
Gm. 
I. 42 
I - 39 
1.32 
36. 10 
38. 55 
28. 85 
29. 62 
33-80 
3i- 19 
48.42 
48. 70 
S 1, 97 
49- 2S 
S3- 67 
S°- 49 
Oven- 
dry 
weight 
stalks 
and 
leaves. 
Gm 
O. 26 
. 26 
. 26 
4.78 
S- °9 
3- 93 
4. IO 
4. 78 
4.27 
5- 99 
6. 22 
6.61 
6- 34 
7. OO 
6.48 
Oven- 
dry 
weight 
roots. 
Gm, 
O. 10 
.09 
. 10 
1. 29 
i- 39 
1. 10 
1. 14 
1. 23 
1. 17 
1.87 
1.88 
1. 91 
1. 67 
1. 91 
1. 70 
Aver¬ 
age 
oven- 
dry 
weight 
of 
stalks 
and 
leaves. 
Gm. 
o. 26 
4. 60 
4- 38 
6. 27 
6. 61 
Aver¬ 
age 
oven- 
dry 
weight 
of 
whole 
plant. 
Gm. 
O. 36 
5 * 86 
5- 56 
8. 16 
8-37 
Iron 
(EeaOs) 
in dry 
stalks 
and 
leaves. 
Per ct. 
o. 040 
038 
023 
038 
Nitro¬ 
gen (N) 
in dry 
stalks 
and 
leaves. 
Per ct. 
3 -90 
3- 72 
3- 90 
3- 70 
3.80 
Experiment 2 (Source of iron: Ferrous sulphate. Three different 
quantities of iron in acid and neutral solutions).—Since it was thought 
that in experiment 1 so much iron was used as to obscure partially the 
effect of the reaction on the assimilation of iron, an experiment was 
conducted using different quantities of iron in acid and neutral solutions. 
As a check on the previous results, two lots received iron at the same 
rate as in experiment 1—that is, 0,008 gm. of iron per liter for the first 
10 days, 0.004 g** 1 - for the second 10 days, and 0.002 gm. for the last 
20 days of the experiment. The other lots received either 0.008 or 0.002 
gm. per liter during the whole 40 days. Ferrous sulphate was used as 
the source of iron. One plant was grown in each flask, six flasks were 
taken as a unit, and the units triplicated for each treatment. The 
weights of the plants with the percentages of nitrogen, phosphoric acid, 
and iron in the dry substance are given in Table II. 
The color of the plants during growth was as follows: After 7 days 1 
growth plants 55 to 72 were yellowish green, plants 91 to 108 and 73 to 90 
were light green, plants 1 to 54 were dark green; after 12 days’ growth 
plants 55 to 72 were light green and all others were of a good green color. 
It is apparent from this experiment that the effect of the reaction of the 
solution depends somewhat on the quantity of iron supplied, this reaction 
being more evident in solutions containing a small amount of iron. 
1 This is not definitely proved by this experiment alone, but further work substantiated it. 
