. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. £33 divides by a vertical septum, parallel to a plane touching the centre of its outer sur- face. This meets the perpendicular wall last formed at 45°, and divides the cell into an external tetrahedral, and an internal three-sided compartment. The latter divides twice by septa, which cross each other at right angles, so as to form a central group, which, as it rapidly enlarges, causes the four less actively growing cells by which it is sur- rounded to assume a tabular form. In its further development it is converted into
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. £33 divides by a vertical septum, parallel to a plane touching the centre of its outer sur- face. This meets the perpendicular wall last formed at 45°, and divides the cell into an external tetrahedral, and an internal three-sided compartment. The latter divides twice by septa, which cross each other at right angles, so as to form a central group, which, as it rapidly enlarges, causes the four less actively growing cells by which it is sur- rounded to assume a tabular form. In its further development it is converted into a mass of very numerous and minute regularly- arranged tessellar cells, in each of which is found " a lentil-shaped vesicle which occupies the greater part of its ; Shortly before the antheridium arrives at maturity, the mem- brane of the cells disappears ; the vesicles float free, and there is now found rolled up in each, a spiral fibre of from 2\ to 3 coils, which is coloured yellow by iodine. The ripe antheridium presents the. general form and ap- pearance shown in fig. 156. The cellular mem- Fig. 156. Section of young shoot of Anthoceros levis, passing through the lacuna in which the antheridia are deve- loped. The rudiments of the antheridia springing from its floor, project upwards into its cavity. 50 diam. is filled with watery fluid, and roofed over by the cellular layer above ; Each of the cells forming the floor of the lacuna, is divided by two septa, one parallel to the axis of the frond, and perpendicular to its surface, the other also perpendicular, but Cutting the first at right angles. The membrane of each of the resulting small cells buds out upwards, so as to project into the lacuna, and soon after, the upper projecting portion is cut off from the rest by a transverse septum, and becomes the parent cell of the antheridium. A second septum is then formed above the first, and parallel to it. This is succeeded by a third, which
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