The spindle figure of the somatic mitosis in the young prothallium cells of Osmunda japonica THUNB. was studied morphologically on living material. In the late prophase the interior of the nuclear cavity is taken up by chromosomes and the atractoplasm, which is considered to be a derivative of the karyolymph, while outside the cavity, especially in the neighbourhoodof the poles, there is active cytoplasm. Upon development of the prophase nucleus into the metaphase spindle, the nuclear cavity changes progressively from a spherical to a fusiform shape, in such manner that an interface continues to separate the nuclear contents from the cytoplasm, thus preventing any mixture of the two. The disappearance of the nuclear membrane, and the consequent possibility that the nuclear contents may have become mixed with the cytoplasm in the fixed materials, may be considered a result of artefacts caused by fixatives The interface of the metaphase spindle figure, which gradually changes its shape, exists even in the telophase, where it appears as the phragmoplast. Throughout the stages from the metaphase to the early telophase, the spindle figure acts in respect both of its form and its function as a system independent of the cytoplasm. The cell-plate grows laterally in the phragmoplast and develops into a cell wall from the point of contact with the mother cell membrane. The cell wall, therefore, is built up progressively from one side to the other. After the formation of the cell wall the residue of the phragmoplastsubstance assumes a cytoplasmic nature and disappears into the cytoplasm.
1. In Iris japonica, an allotriploid plant, 13.2% of the ovules had each an embryo sac with normal structure, in 39.2% the embryo sac showed. incomplete development, and 32.2% had abnormal, embryo sacs (Table 2), therefore at least 86.8% of ovules were sterile. 2. 63.4% of the pollen grains were found to be viable (Table 3). 3. There were observed some ovules having two or three megaspore mother cells (Table 1). These mother cells were situated either side by side or end to end in the nucellus. The processes of the development of the embryo sac suggest that they are probably unable to develop into twin or polyembryo.
Ein Vakuumrohre-Potentiometer, der vor einigen Jahren von Prof. K. Shibata unter Mitwirkung von Prof. M. Shibusawa zum Zweck der bioelektrischen Potentialmessungen zusammengestellt worden ist, wird kurz beschrieben. Der Apparat misst an biologischen Objekten die Potentialdifferenzen in weitem Bereich bequem und schnell mit einer Genauigkeit von±0.2mV.
Through the kindness of Dr. AKAMARO TANAKA and Mr. RYÛITI HOSINO, I have been enabled to examine some microscopical plants which were collected in September of 1933 by them in Itibisinai-ko, a mineralogenous acidotrophic lake, in Kunasiri-zima of the South Kurile Islands and have found 3 diatoms, viz. Pinnularia Braunii, Pinnularia Braunii var. amphicephala, and Eunotia septentrionalis. Among them, a number of abnormal specimens of Eunotia have been found.