492 
S. C. BROOKS 
Table 4 
Effect of Balanced and Pure Salt Solutions on Exosmosis from Unleached 
Tissue 
Time in Hours After 
Transfer to Distilled 
Water 
Conductance in Ohms, X of Distilled Water in 
Previously Exposed 30 Min. to 
Contact with Tissues 
Balanced Solution 
NaCl 0.22M 
CaCl2 o.x-jM 
0.75 
55-0 
78.5 
73-5 
I.OO 
63.0 
88.0 
78.7 
1-25 
67.8 
94.0 
83.0 
1.50 
71.0 
98.0 
84.5 
2.00 
77.8 
106.0 
88.3 
2.50 
81.8 
112.3 
91.7 
3-50 
91.7 
128.4 
1 00, 1 
Summary 
1. Sodium salts increase the rate of exosmosis of other electrolytes 
from the protoplasm of Taraxacum officinale. 
2. Calcium salts decrease this rate. 
3. A solution may be prepared consisting of a mixture of various 
salts in proportions such that, when used at a concentration isotonic 
with the protoplasm, it causes no appreciable alteration in the per- 
meability of the plasma membrane of Taraxacum officinale. 
Harvard University, 
Laboratory oi? Plant Physiology. 
BIBLIOGRAPHY 
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Toxic Solutions. Ann. Mo. Bot. Gard. 2: 459. 191 5. 
2. . Electrolytic Determination of Exosmosis from the Roots of Plants Sub- 
jected to the Action of Various Agents. Ann. Mo. Bot. Gard. 2: 507. 1915. 
3. Osterhout, W. J. V. The Permeability of Protoplasm to Ions, and the Theory of 
Antagonism. Science, n. ser., 35: 112. 1912. 
4. True, R. H., and H. H. Bartlett. Absorption and Excretion of Salts by Roots, as 
Influenced by Concentration and Composition of Culture Solutions. I. Con- 
centration Relations of Dilute Solutions of Calcium and Magnesium Nitrates 
to Pea Roots. U. S. Dept. Agr. Bur. PI. Ind. Bull. 231. 1912. 
5. . The Exchange of Ions between the Roots of Lupinus albus and Culture 
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6. . The Exchange of Ions between the Roots of Lupinus albus and Culture 
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Speicherorgane von Allium Cepa und Beta vulgaris. Prings. Jahrb. fiir wiss. 
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