Extraction of an Emulsion-Stabilizing Substance from Nitella with Distilled Water

Abstract

Nitella cells, kept in distilled water for 3 days,∗ lose their irritability and their characteristic behavior with potassium. 1 This is apparently a result of the extraction from the cell surface of some organic substance or substances, which we may designate as R. Presumably R is constantly produced by the normal metabolism of the cell and accumulates in the cell surface if the cell is bathed by a balanced solution. In distilled water, or dilute solutions of alkali chlorides, R is dissolved from the surface more rapidly than it enters it.

Can the giving off of substances be detected? Groups of 5 Nitella cells were stored in 10 cc. of the solutions indicated in Table I, in 15 cc. stoppered test tubes. After 3 days, the cells were removed, 3 cc. of CHCl₃ added to each tube, and the tubes vigorously shaken. In Tubes 1, 4, 5, 7, and 8 the emulsion broke up in a few minutes, the water and CHCl₃ forming discrete layers. In Tubes 3, 6, and 9 the CHCl₃ settled in large drops, which coalesced in the course of about 1 hour. In Tube 2, which had contained distilled water and Nitella cells, the CHCl₃ layer was broken up into many very small drops, and the emulsion persisted for days.

It is evident that cells which show no signs of injury can give up to distilled water substances which stabilize an emulsion of CHCl₃ and water. This action is very much less when the cells are bathed by calcium solutions or a balanced solution such as Solution A.† More of R is given up to distilled water by intact Nitella cells in 3 days than can be extracted from the killed cells, thus supporting the idea that R is constantly produced and given off.