Anaphase begins with the separation of the daughter chromosomes at the nuclear plate (Fig. 6 ) and ends with the gathering of these structures at the poles of the spindle preparatory to the organization of the daughter nuclei. As the chromosomes move towards the poles the fibers of the central spindle stand out sharply (see Fig. 6 b}. If a cell wall is to be formed between the daughter nuclei one may expect to find these fibers thickening in the equatorial region of the
spindle where the nuclear plate formerly lay. Such thickenings are granular accumulations formed by the contraction of the central spindle fibers and mark the beginnings of the cell -plate (Fig. 8 d} that afterwards gives rise to the cell wall. When the daughter chromosomes reach the poles of the spindle they generally lie in a region of granular kinoplasm which results in part from the contraction of spindle fibers and in some cases from the breaking down of organized centrospheres (e. G., Coral lina, Pellia, Fucus, etc.). The daughter nucleus at this time (Fig. 7 a, b] is in its simplest terms, as explained in Section I, a group of chromosomes surrounded by granular kinoplasm and without the nucleolus, linin network or the vacuole which later contains the nuclear sap.
FIG. 6. Anaphase of Mitosis, spore mother-cell of Lilium martagon. A, immediately after metaphase of first mitosis; each daughter chromosome consists of two grand daughter segments, adhering at the ends, making the familiar V-shaped figures characteristic of the first mitosis (heterotypic) in the spore mother-cell of higher plants, b, late anaphase of the first mitosis; the V shaped chromosomes, each composed of two grand daughter segments adhering at the ends, are very close to the poles of the spindle ; the central fibers of the spindle are conspicuous at this stage, c, second mitosis ; the grand daughter chromosomes, that composed the Vs of the first mitosis, have separated at the nuclear plate of the second mitosis and are being drawn by their ends to the poles of the spindle where they will organize the nuclei of the pollen grain; this mitosis is called homotypic to distinguish it from the usual (typical mitoses in which there are no premature divisions of the chromosomes. All figures after Mottier.
