Electron Microscope Studies on the Mitotic Figure

Under the electron microscope the developmental process of the spindle has been studied in the meiosis of pollen mother cells in Lilium lancifolium, L. longiflorum and L. speciosum applying the treatment of cadmium chloride solution.2. As prophase proceeds to its end, innumerable granules appear and localize at first inside of the nuclear membrane. Then the granules assemble on the surface of the chromosomes, and distribute themselves further evenly in the nuclear cavity at the end of the prophase.3. At the interval between the end of diakinesis and the beginning of metaphase, short fine fibrils appear in the nucleus where the granules were previously seated. These fibrils show at first no orientation but later they orientate parallel to the spindle axis. These fibrils make up the unit fibrils of the metaphase spindle.4. During this stage the chromosomal fiber develops from the kinetochore of each chromosome towards the pole, binding the unit fibrils of the atractoplasm into a fiber. Therefore, the fact that the chromosomal fiber as well as the unit fibrils of the spindle is nuclear in origin has been confirmed at the submicroscopic level.