Summary: | There has been described elsewhere (1, 2) a permeability phenomenon analogous in certain respects to chemical catalysis but involving a diffusion process rather than a chemical reaction. It now appears that this phenomenon of "catalyzed diffusion, " as it may be called for brevity, is of wider applicability than was at first suspected. The present paper deals with certain recently investigated aspects of this question. The work had its origin in the observation of 0rskov (3, 4) that the rate of hemolysis of mammalian erythrocytes in solutions of ammonium chloride can be enormously increased--that is, 50 times or more--by the addition of a little bicarbonate. 0rskov in his first paper (3) suggested that carbonic acid has a specific effect of some sort on the erythrocyte which makes it more permeable to anions; later (4) he modified this view and postulated instead an increased permeability of the cell to the ammonium ion. For various reasons which have in part been set forth elsewhere (5) neither of these explanations seems to be satisfactory, and there has been proposed in their place the principle of catalyzed
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