Abstract
(1) The tonicity of the metaphase I cell of Tradescantia virginiana L. was approximately determined by plasmolysis, using balanced salt solutions.
(2) The influence of the cH of the surrounding medium upon the distinctness of the chromosomes in the cell was investigated by using a series of approximately isotonic balanced solutions with varying cH. The cH of the natural medium of the cell, i.e., the pollen-sack slime, seems to be the most favourable one for the presumably normal appearance of the chromosomes.
(3) The chromosomes are quite distinctly visible in the cells immersed in the presumably isotonic solution of saccharose, though the cells are slightly plasmolyzed due to a peculiar effect of saccharose solution an the plasma-membrane of the cell. These cells are capable of continuing divisions under the microscope.
(4) The tonicity of the cell appears to rise considerably as the stage of division proceeds.
(5) The presence of the pollen-sack slime is necessary for the completion of cell-wall formation.
The writer wishes here to express his hearty thanks to Professor SAKAMURA for his kindness in furnishing ample material and in bestowing valuable criticism and suggestion during the course of this work. Further the writer is greatly indebted to Professor INUKAT for his kind helps and advice during the preparation of manuscript.
