RECORD OF THE EXPERIMENTS. 21 
EXPERIMENT 2. 
Experiment 2 embraced a series of Ca(NO,), solutions, grading 
from distilled water to ae Conductivities were read at the end of 
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7 days and again at the end of 14 days from the date of starting. 
Temperatures: 22.5° at start, 23.2° after 7 days, and 23.4° after 14 
days. 
CHANGE /N CONCENTHATION DURING GROWTH. 
Fig. 9.—Curve showing relation of initial concentration of culture solutions to absorption and excretion 
2M 
of salts during growth in solutions of Mg(NOs3)2 grading by increments of 500, 000 from distilled water 
to 26 M . 
500, 000 
This series indicates that the concentration at which income and outgo 
balance one another is rather less for calcium nitrate than for magne- 
12M 
500,000 - 
shows that the roots have a much higher efficiency in absorbing from 
calcium than from magnesium solutions when the concentration of 
the original solution is greater than the equilibrium concentration. 
This is what would be expected from a consideration of the fact that 
all the magnesium solutions used in experiment 1 had a distinctly 
toxic effect as compared with distilled water, whereas the effect of 
the calcium was decidedly stimulating. (Fig. 10.) 
231 
sium nitrate, being sooo as compared with Moreover, it 
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