1) A monolayer of lipids from bovine tongue epithelium was prepared as a model system for the taste receptor membrane and the influences of anion species on the surface potential were examined. The anion influence observed with the monolayer was closely correlated with that obtained with taste reception of the frog.
2) The suppressive effect of salts on the response of the frog to sugars was examined by measuring activities of taste nerve. The order of effectiveness of the suppression was NaCl, KCl<MgCl₂<MgSO₄<K₄ [Fe (CN) ₆]. Plots of the response against the ionic strength fell on a single curve, which implied that the sugar response of the frog was suppressed by an increase of the ionic strength.
3) The lipid monolayer penetrated with urease was prepared as a model system for a membrane containing a specific receptor protein. The change in the surface potential of the monolayer was observed with variation of concentration of urea or thiourea. No change in the surface potential was observed with use of inactive urease. It was inferred that the binding of the substrate to the enzyme induced a conformational change of the lipid membrane, which brought about a change in the surface potential.
4) The fluorescence intensity of ANS in liposome suspension and the zeta-potential of he 1 iposome were measured as a function of concentration of various salts. It was concluded that an enhancement of fluorescence intensity is stemming from the changes in the surface potential of the liposome.
5) Based on the analysis of the experimental results described above, discussion was made on the significance of the phase boundary potential in the membrane potential of biological systems.

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Loeb-Sourirajan type cellulose acetate membrane developed for the reverse osmosis process has the asymmetric structure, that is composed of a thin dense layer and remaining porous substrate. Characteristics of each layer were separately determined in this experiment using membranes, whose reverse osmosis characteristics had already been determined. First the diffusivity of NaCl in the porous layer (B) was determined by measuring the release rate of NaCl into water through it after equilibrating the membrane with the solution of certain NaC1 concentrationn Next the permeability of the dense layer (A) was determined by the same procedure except for diffusing through both A and B. Other properties, such as distribution coefficients, water contents and layer thicknesses were determined for B. Those for A could not be determined because of its thinness. Though B layer has no relation with the reverse osmosis separation, its properties are interesting to show the general characters of porous cellulose acetate membranes. With the increase of heat-treatment temperature, water contents decrease, distribution coefficients increase and diffusivities remain constant. Solute permeability of A layer agreed well with that obtained from the reverse osmosis experiment except for membranes with large permeabilities. These results show that transport equations and experimental methods used are correct.

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