. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE JUNGERMANNIALES 8i antheridium body (Fig. 33, D). At this stage and the one preceding it Sphcerocarpus recalls the structure of the anther- idium of the Characeas, although the succession of walls is not exactly the same. The divisions of the central cells are ex- tremely regular, walls being formed at right angles, so that the sperm cells are almost perfectly cubical, and the limits of the primary central cells are recognisable for a long time. The development of the antheridial envelope
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE JUNGERMANNIALES 8i antheridium body (Fig. 33, D). At this stage and the one preceding it Sphcerocarpus recalls the structure of the anther- idium of the Characeas, although the succession of walls is not exactly the same. The divisions of the central cells are ex- tremely regular, walls being formed at right angles, so that the sperm cells are almost perfectly cubical, and the limits of the primary central cells are recognisable for a long time. The development of the antheridial envelope begins much earlier than that about the archegonium, but in exactly the same way. By the time that the wall of the antheridium is formed the envelope has already grown up above its summit, and as the antheridium develops it extends far beyond it like a flask, at the bottom of which the antheridium is placed, and through whose neck the spermatozoids escape. These are A B £. Fig. 33.—Spharocarpus sp (?). Development of the antheridium. A-D, Median lon- gitudinal sections, X450: E, an older one, X225; F, a spermatozoid, killed with osmic acid, X900. very much like those of the other Hepaticse, and in size exceed those of most of the Marchantiacese, but are smaller than is usual among the Jungermanniales. Leitgeb studied the germination of the spores in ^. terres- tris, which remain permanently united in tetrads. He found that all the spores of a tetrad were capable of normal develop- ment, which does not differ from that of Riccia or other thal- lose Liverworts. A more or less conspicuous germ tube is found at the end of which the young plant develops, one of the octants of the original terminal group of cells becoming, appar- ently, the apical cell for the young plant. The latter rapidly grows in breadth and soon assumes all the characters of the 6. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colo
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
