Apr. 16,1917 
Absorption of Nutrients 
87 
EXPERIMENT X.—RICE WITH HATE THE ROOTS IN AN IRON-FREE SOLU¬ 
TION (FERRIC TARTRATE SOURCE OF IRON) 
The results of the previous experiment were not decisive, as there 
was a strong probability that neither the complete- nor the partial-iron 
plants had a sufficiency of iron available in the solution. Previous work 
showed, however, that in the acid solution with 0.008 gm. of iron per liter 
from ferric tartrate, plenty of iron was available; in fact, rice absorbed 
a certain excess of iron from this solution. Accordingly a test was 
run, using the acid solution with ferric tartrate. 
In this test no plants were grown without iron, as the previous test 
and many others (5) showed that the growth of such plants was prac¬ 
tically nil. Therefore, it would not appreciably affect the figure for the 
relative amounts of iron absorbed by partial- and complete-iron plants 
whether the quantity of iron in the no-iron plants was subtracted or 
not. The plants were grown 24 days in 200-c. c. flasks and 16 days in 
500-c. c. flasks. Seven flasks were taken as a unit and the units dupli¬ 
cated for each treatment. Solutions were changed 10 times during the 
experiment. The results are given in Tables XX and XXI. 
Table XX .—Growth of rice in Experiment X 
Nutrient solution. 
Flask 
No. 
Weight of stalks 
and leaves. 
Number of 
roots. 
Average oven- 
dry weight 
of roots. 
Ratio 
of 
roots 
to 
tops. 
A-flasks. 
B-flasks. 
Green. 
Oven- 
dry. 
Aver¬ 
age 
oven- 
dry. 
A- 
flasks. 
B- 
flasks. 
A- 
flasks. 
B- 
flasks. 
Iron-free. 
Complete. 
f 1 - 7 
\ 8-14 
/15-21 
\22-28 
Gm, 
260. 5 
277-1 
304-3 
320.8 
Gm. 
37-u 
40.46 
43-23 
46.79 
Gm. 
I38* 79 
j45- 01 
/ 392 
t 383 
/ 358 
l 396 
379 
361 
378 
403 
Gm. 
} 4- 23 
} 5-53 
Gm. 
5-38 
S- 95 
0.248 
•255 
Complete.. 
.do. 
Table XXI.— Iron, nitrogen , and phosphoric acid absorbed by rice in Experiment X 
Flask No. 
Iron (Fe203>. 
Nitrogen 
(N) m dry 
stalks and 
leaves. 
Phosphoric 
acid (P2O5) 
in dry stalks 
and leaves. 
In dry 
stalks and 
leaves. 
Absorbed 
by 14 plants. 
Absorbed 
per gram 
of roots. 
. 1-14 
15-28 
Per cent. 
O. 0189 
. 0246 
Gm. 
O. 00733 
. Oi107 
Gm. 
0. 00136 
. 00096 
Per cent. 
3 - 64 
3 - 53 
Per cent. 
1. 34 
i- 33 
Comparison with the complete-iron plants (15 to 28) shows that the 
partial-iron plants (1 to 14) absorbed 0.66 as much iron and 1.43 times 
as much iron per gram of roots. The ratio of roots to tops and the 
percentages of nitrogen and phosphoric acid in the dry substance varied 
little between the two lots of plants 
