The deepithelialized cornea is mounted in a chamber and perfused on both surfaces by identical closed systems. The technique allows the continuous measurement of the net water flux and the electrical potential across the preparation as well as the steady state flux of radioactive ions. The permeabilities of pairs of ions in the same direction were compared, and they were found to be closely proportional to their free diffusion constants, suggesting that they passed by way of the intercellular spaces. Technical difficulties prevented a valid determination of the existence of active ion transport, but there was no indication of its presence.