On the Plasmolysis Form in Allium cepa with Special Reference to the Influence of Potassium Ion upon It

Abstract

1. When the epidemis cell of Allium cepa is plasmolysed with a 0, 5 mol KCl solution, concave plasmolysis continues longer than hitherto expected, if the material is preserved in healthy condition and its treatment during the experiment is carried out carefully.
2. When KCl is used as the plasmolyticum, the difference of the material and the experimental condition react more sensitively in the plasmolysis form and time than when CaCl₂, or saccharose is used.
3. Judging from the plasmolysis form the liquefying action of K^. on the cytoplasm increases accompanied by the increase of hydrogen ion concentration.
4. Light has remarkable influence on the plasmolysis form and time. The plasmolysis time is shortened by illumination of the preparation. This is theoretically in accordance with the well-known fact that the light increases the permeability of the protoplasm.
5. In order to have uniform healthy material of Allium cepa for the purpose of the experiment on the plasmolysis form, it may be recommended that the bulb or the separated scale leaf be kept cool and wet, or better in cool water. This was confirmed by repeated experiments in the present investigation.
6. Ca^.. and A1^.. act antagonistically against K^. in relation to the plasmolysis form. The plasmolysis time is greatly prolonged by the addition of these ions.
A part of the present study has been carried out at the Laboratory of Plant Physiology of Prof. T. Sakamura, Sapporo, to whom the writer wishes to acknowledge his sincere gratitude for granting him the facilities of the laboratory. The writer expresses his thanks equally to the Japan Society for the Advancement of Cytology, by the grant from which this work was supported.