Data are presented which suggest that the internal lens fibers are not degenerate. It is shown that the anterior surface of the frog lens maintains about a 5 mV greater potential than the posterior. This gradient presumably represents an IR drop along a lens fiber. When the K + concentration of the bath is increased, the anterior surface depolarizes at a slightly faster rate so that the two surfaces become isopotential at high bath K + concentrations. The anterior and posterior potentials also change at different rates in hyposmotic SO 4 = solutions and in choline chloride Ringer's. The potential reducing effect of surgical trauma on the lens is described and proper methodology for lens P.D. measurements is suggested. The depolarizing effect of ouabain is discussed.