On the Effect of a Centrifugal Force upon the Egg Cell and Proembryo of <i>Pinus Thunbergii</i> PARL. With Some Observations on Various Effects of Fixing Agents in the <i>Pinus</i> Egg Cell

Abstract

1. The nucleolus in the egg nucleus is relatively much heavier than the other constituents of the nucleus.2. As the proteid vacuoles have almost the same density as the cytoplasm in which they are embedded, they are not thrown into clearly defined zones in the centrifuged egg cell.3. In the early proembryo stage, where the 2 or 4 free nuclei are found somewhat above the centre of the egg cell, they cannot be dislocated by the application of a centrifugal force such as used by the writer. This indicates that there is no marked difference in density between these free nuclei and the surrounding cytoplasm.4. In the proembryo stage, after the four nuclei have reached the bottom of the egg cell a marked change occurrs in the consistency of the general cytoplasm. The four centrifuged nuclei can be easily moved towards the centrifugal end through the general cytoplasm of the egg cell, indicating a decrease of the density of the egg cytoplasm, rather than an increase of the density of the proembryonal nuclei.5. At the eight-nucleate stage, the nuclei of the upper tier can be easily driven out of the tier in a centrifugal direction into the general cytoplasm.6. In the egg nucleus Of Pinus Thunbergii fixed with either BENDA'S or CHAMPY's fluid, no clear nuclear membrane is observed, and the nuclear cavity is filled with homogeneous finely granulate fixed substance, while in the material fixed with either FLEMMING'S or BOUIN's fluid clear nuclear membrane is observed, and nuclear cavity shows distinct reticula, being free from finely granulate homogeneous substance.I have much pleasure in expressing here my cordial thanks to Emer. Professor K. Fu ii for his kind advice and criticism throughout the course of this experiment, which was chiefly carried on in 1925-1926, and supplemented in the summer of 1927.