The rate of electroendosmotic flow through dog and cat pericardia is found to be proportional to the current strength. The plots of current strengths against volumes of liquid transported in unit time are, in the better experiments, straight lines passing through the origin; the slopes of the lines are characteristic of the several systems. Data on transport rate with buffers of different specific resistances showed the following phenomena: 1. Decrease of the observed transport rate to a minimum between σ values of 95 and 60 ohms. 2. Changes in the membrane markedly affecting transport rate, at conductivities and osmotic pressures close to those of the blood. 3. Polarization of the membrane during the passage of current. The mean rate found for electroendosmotic transport across dog and cat serous membranes bathed in serum has been 0.19 to 0.30 (average, 0.25) c.mm. per minute per milliampere. The best experiments with dog serum and the living mesenteries of dogs under ether gave a mean rate of 0.29 c.mm. per minute per milliampere. These data, together with data from other sources, are believed to indicate a probability approaching certainty that electroendosmotic effects are a factor in glandular secretion.