Apr. 7,1923 Nutrition of Plants as an Electrical Phenomenon 
49 
Tabi,^ VI. —Analyses of 100 wheat plants given an abundance of plant food in the first 
period, placed in distilled water for the second period, and again placed in nutrient 
solution for two or more days 
No. 
Days in nutrient solution in third period. 
Dry weight. 
N 
K2O 
P ?05 
I 
Control 0. 
Gm. 
3 - 92 
Gm. 
0. 1596 
Gm. 
0. 1500 
Gm. 
0. 0960 
2 
I . 
5. 88 
. 2172 
. 1998 
. 1320 
3 
2. 
5. 68 
. 2320 
■ 2506 
. 1400 
4 
3 . 
5 - 90 
. 2605 
. 2670 
. 1380 
By subtracting the nitrogen in the control, o. 1596 gm., from the nitrogen 
in the i-day plant (No. 2), 0.2172 gm., we get 0.0576 gm. nitrogen 
absorbed in one day. By subtracting the control from the 3-day plants, 
we get 0.1009 gm. instead of three times 0.0576 gm., or 0.1728 gm., which 
we might expect if time alone governed absorption. In the KjO column 
one determination, the absorption in 2 days, seems to be a little out of 
line and high. From these experiments one would judge that a demand 
for any of the plant foods can be developed in the plant, that this demand 
is cumulative, and that it is possible to measure this demand by analytical 
means. 
DEMAND OF WHEAT PLANTS GROWN IN NUTRIENT SOLUTION FULL 
TIME AND ALTERNATE DAYS 
As nitrates, and possibly other plant foods, are likely to vary in the soil 
solution from day to day, it was thought of interest to measure the rate 
of absorption when nutrients were given at varying intervals—that is, 
to measure the rate of absorption when cultures were placed in nutrient 
solution one day and in distilled water the next, and in nutrient solution 
on the third day and so on, feasting for one day and fasting the next. 
These seedlings were grown both with an abundance of plant food (100 
parts per million each N, KjO and PgOg) and also with a limited amount 
(10 parts per million). Analyses of the 12-day-old plants are given in 
Table VII. 
Table VII. —Analyses of 100 wheat plants grown continuously in nutrient solutions 
for 12 days, compared with similar series placed in distilled water every other day 
Na 
Treatment. 
Dry weight. 
N 
K2O 
P2O8 
I 
Distilled water control. 
4.44 
0. 0924 
0. 0597 
0. 0720 
2 
Nutrient solution 100 p. p. m. full time. 
4* 68 
. 1988 
. 2561 
. 1080 
3 
Nutrient solution 100 p. p. m. one day, 
distilled water one day. 
5-36 
. 2100 
. 2856 
. 1280 
4 
Nutrient solution 10 p. p. m. full time.. 
S- 76 
. 1932 
.2273 
. 1200 
5 
Nutrient solution 10 p. p. m. one day, 
distilled water one day. 
S- 92 
• 1736 
. 1940 
. 1180 
This was repeated several times with similar results. The total quan¬ 
tity of plant food absorbed, when plenty of plant food was present, 
was greater in the plants that had grown in the nutrient solution only half 
time than in the plants that had grown all the time in the same nutrient. 
When a limited quantity of plant food was present, the quantity 
30615—23-4 
