. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Antherozoids of Pellia, 400 diam. (Thuret.) tlie shoot below them, a thin laminar prolong- ation upon the surface of which they are sup- ported. By a process of cell-division resem- bling that observed in the development of the untheridia of Anthoceros, each rudiment is converted into a cylinder, rounded above and consisting of a single central cellular column, surrounded by a single layer, which is formed of four perpendicular series of flattened cells in contact with each other by their edges. The cells of the central
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Antherozoids of Pellia, 400 diam. (Thuret.) tlie shoot below them, a thin laminar prolong- ation upon the surface of which they are sup- ported. By a process of cell-division resem- bling that observed in the development of the untheridia of Anthoceros, each rudiment is converted into a cylinder, rounded above and consisting of a single central cellular column, surrounded by a single layer, which is formed of four perpendicular series of flattened cells in contact with each other by their edges. The cells of the central column contain granular mucus, in which ve- sicular nuclei are embedded. As the arche- gonium becomes fully formed, the lowest cell in the series, as well as its nucleus, enlarges, and the cells of the outer wall in its neigh- bourhood rapidly multiply, so that the organ becomes swollen out at its lower part. The development is completed by the disappearance of the transverse septa, which separate the cavities of the cells forming the central column. In this manner is produced an axile channel, closed above, and terminating below in a flask-shaped dilatation, in which Fig. Archegonium of Jungermannia bivaricata at period of impregnation, 400 diam. Cellules containing antherozoids are observed at the entrance of the canal. the enlarged nucleus of the basal cell (germ- cell) is contained. Soon the cells forming the summit of the archegonium give way, so as to open a communication between its cavity and the external atmosphere. 69. Second period.—Development of the em- bryo.—In consequence, as there is every reason to believe, of the entrance of the spiral filaments into the cavity of the archegonium, the germ- cell is divided by a tranverse septum into a larger inferior and smaller superior (hemi- spherical) portion. This last next divides by two perpendicular septa crossing each other at right angles, which are succeeded by a third, which is horizontal. This is succe
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