Apr., 1923] ADDOMS-HYDROGEN ION AND PROTOPLASM 219 
theorem [Le Chatelier (’84), Braun (’87)] ,which states that a system affected 
by an outside condition tends to alter within itself in such a way as to oppose 
and partially annul the effects of this outside condition. 8 It thus becomes 
evident that there can be no direct relation between the hydrogen-ion 
concentration of nutrient solutions and the yield of plants grown in them, 
for the hydrogen ion affects the absorbing action of the plant, which in turn 
affects, not any one plant measurement, but all directions of growth. 
Summary 
1. The abnormal root development and decreased growth that have 
been observed in plants grown in nutrient solutions that contain relatively 
large amounts of potassium di-hydrogen phosphate may be explained by 
the coagulation of the protoplasm of the root hairs. 
2. This coagulation, which is accompanied with flocculation, is found 
to be induced by the hydrogen ions formed by dissociation of the phosphate. 
The hydrogen-ion concentration of the nutrient solutions employed varied 
from pH 3.94 to pH 3.47. 
3. The relation of this coagulation and flocculation to the colloid chem¬ 
istry of protoplasm is discussed. 
4. The lack of logic in the attempts of certain investigators to find a 
direct relation between environmental features, such as hydrogen-ion con¬ 
centration, and the dry weight of plants, is pointed out. 
In concluding, I wish to express to Professor Howard E. Pulling of 
Wellesley College sincere gratitude and appreciation for many suggestions, 
constant interest, and other assistance during the progress of the experi¬ 
ments and the preparation of this paper. 
Wellesley College, 
Wellesley, Mass. 
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8 Chwolson (’05), p. 475. 
