Beef blood corpuscles were centrifuged at 20,000 R.P.M. in a centrifuge in a vacuum for different periods up to 30 min. and the effective resistance and capacity of the cells was determined at different frequencies. One cc. of closely packed cells behaved as a circuit composed of a resistance of 1,600 ohms in parallel with a capacity of 1,500 micro-micro farads and these in series with a resistance of 400 ohms. At 1,500,000 cycles the effective resistance averaged about 400 ohms and at 1,000 cycles it averaged about 2,000 ohms. After laking, which destroys the cell surfaces, the effective resistance at 1,000 cycles averaged 400 ohms, showing that the seat of the 1,600 ohm resistance is at the surface. Similar measurements made on curarized turtle''s muscle at rest and stimulated showed that the effective resistance decreased on stimulation.