1. A heat stable germination inhibitor, which is soluble in water and apparenlty insoluble in organic solvents, was found in the pericarp of the spinach fruit. 2. The author and his co-workers succeeded in isolating the inhibitor as crystalline picrate from the water extract of pericarp and fruits. 3. The aqueous solution of this inhibitor was weak acidic (pH=6.8) and its acidity remained almost unchanged for a few days. On the other hand, the crude aqueous extract of the pericarp contained a substance, which, on standing for two or three days, gave rise to strong alkaline reaction (pH=9.0). Presumably it will be different from the inhibitor.
The localization of peroxsdase in the cell of several Spirogyra species was investigated by the aid of benzidine oxidation reaction. The blue staining with the oxidized benzidine was recognized at first on microsomes, nucleoli and septum regions, and then in whole nuclei. Plasmolysing the cells with a 1mol. sugar solution before or after the treatment with reagents, it was revealed that the staining of the septum region was, in general, that of the surface of cytoplasm, i.e. the protoplasm membrane. In the case of certain species of Spirogyra, however, the cell membrane at septum region, as well as the protoplasm membrane, was stained. When the cells were treated with the coloured benzidine solution, prepared by addition of Cl2-containing tap water to the acidified benzidine solution, the cell membrane was stained blue as stated above, though the microsomes, the nucleoli and the protoplasm membrane remained colourless. The staining of microsomes, nucleoli and protoplasm membrane was inhibited by KCN or boiling (10min.), while that of the cell membrane was not by KCN. Therfore, the staining of the cell membrane of these species is supposed to be caused by the secondary adsorption of the dyes. In a poorly growing culture, the pathologically isolated septum apparatuses occasionally adsorbed the dyes. Considering the results of this experiment, it may be concluded with certainty that peroxidase is localized on microsomes, nucleolus and the protoplasm membrane in the cell of Spirogyra.