The cornea is especially suitable for the study of permeability in biologic membranes not only because of its continued functional integrity after the death of the animal but because its anterior layer (epithelium) and posterior layer (endothelium and Descemet's membrane) may be separately removed without appreciable damage to the adjacent substantia propria. By comparing variations in permeability before and after removal of these membranes, it is theoretically possible to allocate the functional characteristics of the permeability to the different layers of the cornea. Nevertheless, recent studies of corneal permeability have been few and have led to conclusions that are mutually contradictory.1Gallenga (1927)2found that salicylates, sulfocyanides and iodine placed on the cornea of the intact eye were subsequently detectable in the aqueous and that, at least in the case of iodine, hypertonic solutions on the outside of the eye caused water to pass through the cornea. From