Dec, x8, 1916 
Assimilation of Iron by Rice 
507 
Table II .—Comparative weights of rice plants grown in acid and neutral solutions with 
three quantities of iron from ferrous sulphate 
Nutrient solution. 
Quantity of iron per 
liter. 
Acid. 
Gw. 
0 . 002 . 
Do. 
.008, O.OO4, 0.002 
Do. 
.008. 
Neutral. 
.002. 
Do. 
.008, O.OO4, 0.002 
Do. 
.008. 
1- 6 
7-12 
13- 18 
19- 24 
25- 30 
3 i- 3634-38 
37^ 42 
43 - 48 
49 “ 54 
55- 60 
61- 66 
67- 72 
OJ 
Gm. 
32. 05 
32.98 
31.40 
30.48 
30.00 
34 - 7 2 
S 3 - 10 
51. 18 
28. 
26. 71 
27. 72 
483 
73 “ 7836-42 
79- 8437 - 75 
85- 90 28. 28 
91- 9659. l8 
97-102 
103-108 
59 - 45 
tv 
$ 
Gm. 
4.04 
4. 12 
3-93 
3 - 90 
3 - 78 
4. 18 
4*37 
6 . 5 8 
6. 12 
73 
3 * 34 
3 - 56 
A 
w 
T « 
i 
& 
Gw. 
I. 04 
1. 08 
.92 
.96 
•95 
• 9 1 
1.32 
1. 92 
1. 80 
.85 
•79 
• 79 
4 * 40; 1. 03 
4.69 
3. 62 
7 - 54 
7 - 49 
i- 15 
.84 
2. 17 
2. 00 
Average 
oven-dry 
weight 
of— 
In dry substances 
of . stalks and 
leaves, percent¬ 
ages of— 
Stalks and 
leaves. 
jwhole plant. 
Nitrogen 
(N) 
O * 
|<5 
•SfC 
X. 
S 
£ 
1 
Gw. 
Gw. 
P. c. 
P. c. 
P. c. 
4*03 
5-04 
4 * 34 
2.31 
0. 037 
j. . 
3 - 95 
4.89 
4 * 55 
2. 20 
•037 
5-69 
7-37 
4. 40 2. 02 
* 034 
_i_ 
3 - 54 
4*35 
4 - 56 
2. 06 
. 024 
4.24 
5 * 24 
4.40 
2. 04 
. 020 
7 - 52 
9. 60 
4.28 
I. 80 
. 028 
Experiment 3 (Sources of iron in acid, neutral, and alkaline solutions: 
Ferrous sulphate and ferric citrate).—This experiment was designed to 
observe the assimilation of iron in a solution containing calcium car¬ 
bonate—that is, a slightly alkaline solution—and to compare the assim- 
ilability of ferric citrate with that of ferrous sulphate. The method used 
in the conduct of this experiment differed from that of other experiments 
only in the making of the nutrient solutions. In all other experiments 
reported the nutrient solutions were made up fresh 18 hours before the 
plants were inserted, and any residue remaining in the bottles from the 
previous lot was thrown away. In this experiment the nutrient solutions 
were made up fresh 18 hours beforehand, but whatever nutrient solution 
remained from the previous change was left in the bottles and added to the 
fresh solutions. This residue increased at times but never amounted to 
more than a quarter of the whole solution. It nevertheless affected the 
results. 
Iron from both ferric citrate and ferrous sulphate was used at the rate of 
0.002 gm. of iron per liter in all the cultures. The alkaline solutions with 
calcium carbonate contained 0.41 gm. of precipitated calcium carbonate 
per liter. One plant was grown in each flash. Six flasks were taken as 
a unit, and the units were triplicated for each treatment. The growths 
of the plants in the different solutions and a partial ash analysis of the 
stalks and leaves are given in Table III. 
