Electric Conductance of Biological Systems

Since the time of Galvani, the electrical phenomena associated with the physiological prooesses of growth, stimulation, injury, recovery and death have received an enormous amount of experimental and theoretical attention. Certain of these phenomena, such as action potentials resulting from some physiological activity, and physiological activity, resulting from an externally applied electric field, may be considered as "active" from the physiological point of view. From the investigations of these activities, much evidence has been accumulated which indicates that in general the living cell may be considered to have an electrically conducting interior enclosed by a comparatively non-conducting membrane—or sheath. There is, furthermore, hoth direct and indirect evidence of the existence of an electric potential difference across this membrane in the normal resting cell. Also, almost any change of the physiological condition of the cell is accompanied by an alteration of this potential difference. Conversely, when the potential difference is changed...