. Nature and development of plants. Botany. NATURE OF PLANTS 57 division delicate colorless strands begin to appear and ultimately grow into a spindle as shown in Fig. 31, D. There are two sets of these strands or fibrillae; an inner and an outer series. The outer fibrillae, in some way not understood, arrange the chromosomes in the center or equator of the spindle (Fig. 31, D) where each. Fig. 31. Cell division in root of corn: A, cell with nucleus enlarging pre- liminary to division—/, linin; ch, chromatin. The central dark body is the nucleolus. B, later stage, the chromatin has increased a
. Nature and development of plants. Botany. NATURE OF PLANTS 57 division delicate colorless strands begin to appear and ultimately grow into a spindle as shown in Fig. 31, D. There are two sets of these strands or fibrillae; an inner and an outer series. The outer fibrillae, in some way not understood, arrange the chromosomes in the center or equator of the spindle (Fig. 31, D) where each. Fig. 31. Cell division in root of corn: A, cell with nucleus enlarging pre- liminary to division—/, linin; ch, chromatin. The central dark body is the nucleolus. B, later stage, the chromatin has increased and appears as a ribbon- like skein. C, formation of the chromosomes, cr. D, formation of the spindle and the arrangement of the chromosomes in the center of the spindle.— I. D. Cardiff. chromosome divides by a longitudinal division into two equal parts. The fibrillae now separate the two halves of each chromo- some and pull them to the opposite poles of the spindle so that each pole receives a half of every chromosome (Fig. 32, £). The chromosomes now become rearranged at the poles and two new nuclei are gradually formed like the original nucleus (Fig. 32, F, G). In the meantime the inner fibrillae of the spindle have shortened and become thicker at the equator (Fig. 32, G). This thickening goes on assisted by the addition of new fibrillae at either side of the spindle until a delicate line (the cell wall) reaches across the old cell (Fig. 32, H), and the division of the mother cell into two daughter cells is completed. In this way new cells are being constantly added to the root. It will be noticed, if a longitudinal section through the middle of the root is examined, that various regions of the elongating root may be recognized owing to the difference in the character of their growth. In such a section (Fig. 33) we see that the tip of the root is covered with. Please note that these images are extracted from scanned page images that may have been digitally enhanced for r
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