. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. fi4 Mosses and ferMs chap. until a short filament is formed. After a varying number of transverse divisions an oblique vi^all is formed in the terminal cell, and a second one nearly at right angles to it. By these divisions the dorsiventral character is established, the first- formed segment being ventral. A third oblique wall now arises, intersecting both of the others, and the three include a tetrahedral cell which is the permanent apical cell of the young plant. The ventral segments do not
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. fi4 Mosses and ferMs chap. until a short filament is formed. After a varying number of transverse divisions an oblique vi^all is formed in the terminal cell, and a second one nearly at right angles to it. By these divisions the dorsiventral character is established, the first- formed segment being ventral. A third oblique wall now arises, intersecting both of the others, and the three include a tetrahedral cell which is the permanent apical cell of the young plant. The ventral segments do not at first form any trace of leaf-like structures, and in the dorsal segments the leaves are at first simple rows of cells; but a little later the leaves show plainly their two-lobed character, each being made up of two rows of cells united at the base. From the ventral segments the amphigastria develop gradually, being quite absent in the earlier ones. Chiloscyphus closely resembles Lophocolea, but. Fig. 59.—^A, Germination of Lejeunia serpyllifolia; B, young plant of Radula com- planata; x, the optical cell (all the figures after Goebel). the filamentous protonema is longer, and is often branched. A similar filamentous protonema is present in Cephalosia (Jun- germannia) bicuspidata and other species. Lejeunia (Goebel (13) ) shows a most striking resem- blance in its early stages to the simple thallose Jungerman- niaceas. The germinating spore forms either a short filament or a cell surface (Fig. 59, A). In either case, at a very early stage, a two-sided apical cell is established, and for a time the young plant has all the appearance of a young Metzgeria or Aneura. This two-sided apical cell gives place to the three- sided one found in the older gametophyte, and the leaves and stem are gradually developed as in Lophocolea. In Radula (Hofmeister (i), p. 55), and according to. Please note that these images are extracted from scanned page images that may have been digitally enha
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