THE ELECTRICAL CAPACITY OF VALONIA : DIRECT CURRENT MEASUREMENTS

Impaled cells of Valonia were balanced in a Wheatstone bridge against a simple series-parallel circuit of two resistances and a capacity, the transient charge and discharge curves at make and break of direct current being recorded with a string galvanometer. With the resistances properly balanced, a series of characteristic deflections resulted when the balancing capacity was varied. With many cells, no complete capacity balance was ever attained over the entire transient time course; but instead either a monophasic or diphasic residual deflection always remained. This behavior is comparable to that of a polarizing electrode in D.C., although not so clearly marked; and it is concluded that Valonia usually has an appreciable polarization component, probably in parallel with a static capacity. However, some cells can be balanced almost completely against a mica condenser of proper value, which indicates that they display a nearly pure static capacity under some conditions. This static state could be produced experimentally by exposure to weak acids (acetic, carbonic, etc.) and by metabolic agents probably inducing internal acidity (low oxygen tension, long exposure to cold, narcotics, etc.). Conversely, penetrating weak bases, such as ammonia, abolished the static capacity, or even any regular polarization. Light acts something like ammonia, after an initial "acid gush" anomaly. Most of these agents likewise affect the P.D. and its response to external ionic alterations, and it seems likely that the change in capacity type reflects altered ionic permeabilities and relative mobilities.