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Publisher Summary This chapter discusses the Charles Ernest Overton's concept of a cell membrane. Overton presented his views on the osmotic properties of cells and established several milestones in the field: (1) A “lipid-impregnated boundary layer” is a determinant of the osmotic properties of living cells. Both diffusion- and metabolism-linked active processes function in solute exchange between cells and their immediate environment. (2) The lipids of the cell (membrane) are involved in the phenomenon of narcosis. (3) An exchange of sodium and potassium across the membranes of muscle and nerve cells is responsible for their excitability. The chapter describes the experimental basis for these crucial elements of a concept of the structure and function of a cell membrane. The chapter outlines the background on Overton's establishing of his scientific status primarily by his papers on the osmotic properties of cells. The chapter mentions the phenomenon of plasmolysis—that is, a retraction of the protoplasm from the cellulose wall of plant cells exposed to impermeable external solutes. Overton's systematic exploration of the relationship between the chemical constitution of solutes, mainly organic, and their plasmolytic effects, with reference to the properties of the putative osmotic barrier, was presented in a series of three papers read to the Zurich Naturalist Society. |
