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The results of researches on plasmolysis form and time, started by Weber, Cholodny and others, are now applicable to the ex amination of the colloidal state of the cytoplasm, especially of its outer layer. It is generally accepted that a convex plasmolysis or a short plasmolysis time indicates a low viscosity of the cytoplasm, and a concave plasmolysis or its long duration means a high viscosity.1) But it happens sometimes that contrary to expectation this relation between the viscosity of the cytoplasm and the plasmolysis form appears not to exist, as seen in the case of Cholodny and Sandkewitsch (1933). In the experiments of these authors with epidermis cells of Allium cepa it was shown that K' and Na', which are generally regarded as decreasing the viscosity of the cytoplasm, act to cause concave plasmolysis, instead of convex, which is found to be caused rather by Ca" From these results they assumed that the plasmolysis form is concerned not only with the viscosity of the cytoplasm, but also with some of its other characters. Recently Borries (1938) also remarked in his experiments with Elodea that it is hardly pos sible to examine the normal viscosity of the cytoplasm only according to the plasmolysis form. In the course of the writer's experiments some similar cases to those observed by Cholodny and Sandkewitsch were occasionally met with. This occurred especially when a potas sium salt was used as the plasmolyticum. From various points of view it is very important to explain the reason why such an opposite result is obtained, since it has already been mentioned in many monographs and research works, that potassium salts act to cause convex plasmolysis, while calcium salts cause concave. In the pre sent paper a part of the results of the writer's researches on the plasmolysis form and time are reported, in which potassium salt was used as plasmolyticum, which is apt to cause disagreement of the experimental results in many cases.

On the plasmolysis form in Allium cepa with special reference to the influence of potassium ion upon it