. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. X THE HOMOSPOROUS LEPTOSPORANGIAT^ 377 enia. In the Hymenophyllacese no cap cell is formed, but as in Osmunda and Gleichenia, the upper cell is divided by walls running over the apex. The divisions in the central cell and the structure of the spermatozoids, so far as these have been studied, correspond with those of the other Leptosporangiatse. A single archegonial cushion is not formed, but the arche- gonia occur in small groups at different points upon the margin. Goebel (10) has shown, howe
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. X THE HOMOSPOROUS LEPTOSPORANGIAT^ 377 enia. In the Hymenophyllacese no cap cell is formed, but as in Osmunda and Gleichenia, the upper cell is divided by walls running over the apex. The divisions in the central cell and the structure of the spermatozoids, so far as these have been studied, correspond with those of the other Leptosporangiatse. A single archegonial cushion is not formed, but the arche- gonia occur in small groups at different points upon the margin. Goebel (10) has shown, however, that these archegonial groups arise first near the growing point of the prothallial branch, and that they are simply separated by the intervention of zones of sterile tissue. At the point where they arise the prothaUium becomes more than one cell thick, and in all cases where the development could be certainly followed, the archegonium arose from one of the ventral cells, and never directly from a marginal cell. The details of the development have not been. Fig. 218.—Part of the filamentous prothallium and archegoniophores of Trichomanes rigidum. (After Goebel.) followed, and whether there is any division of the neck canal cell is not known. The neck is straight, as in Osmunda and Gleichenia. In Trichomanes the archegonial meristem (archegonio- phore) may be formed as a short branch, directly upon the fila- mentous prothallium. The lateral walls of the prothallial cells are in all the species thicker than is the case in most Ferns, and there are distinct pits in them. In the rhizoids a parasitic fungus is frequently found. The embryogeny is almost unknown (Janczewski (2)), but the first divisions and the very young sporophyte correspond. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Campbell, Dougla
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