Effects of Various Agents on the Structural Viscosity of Elodea Protoplasm.

Ethylene chlorhydrin, thiourea, and the fat solvent anesthetics, when used in certain concentrations and exposures are often effective in breaking rest periods in plants (8, 13). These agents may also modify the rates of respiration and polysaccharide hydrolysis. The rates of such processes are frequently increased when plants are treated with relatively low concentrations and decreased when treated with higher ones (3, 6, 7, 8, 10, 13, 14, 17, 18, 19). It has been suggested (23) that the breaking of rest periods and accelerated rates of respiration, polysaccharide hydrolysis, imbibition, and permeability are a consequence of a dissociation (disaggregation) of protoplasmic proteins and that the retarded rates which result from longer exposures or higher concentrations are conditioned by an association (aggregation) of protoplasmic proteins. The data presented later indicate that in certain concentrations ethylene chlorhydrin, thiourea, and the fat solvent anesthetics diminish the structural viscosity of protoplasm in leaf cells of Elodea. Decreases in structural viscosity are presumed to result from a dissociation of protoplasmic. proteins (23). Exposures to low temperatures may also influence plants by breaking rest periods (4) and altering the course and rate of development (vernalization). It will be shown that a temperature of 30 C. conditions a decrease in the structural viscosity of Elodea protoplasm. As yet there is no general agreement as to the role of copper and zinc in the metabolism of plants, although it is known that in traces they accelerate one or more plant activities and in larger quantities they are toxic (2). In relatively low concentrations these metals lower protoplasmic viscosity whereas in higher concentrations they increase it.