. The structure and development of mosses and ferns (Archegoniatae). m consistsof eight central cells and eight peripheral ones, and the stalkof two cells, of which the upper one forms the base of the Ill THE JUNGERMANNIALES 8i antheridium body (Fig. 33, D). At this stage and the onepreceding it SpJiccrocarpiis recalls the structure of the anther-idium of the Charace?e, although the succession of walls isnot exactly the same. The divisions of the central cells are ex-tremely regular, walls being formed at right angles, so thatthe sperm cells are almost perfectly cubical, and the limits ofthe p
. The structure and development of mosses and ferns (Archegoniatae). m consistsof eight central cells and eight peripheral ones, and the stalkof two cells, of which the upper one forms the base of the Ill THE JUNGERMANNIALES 8i antheridium body (Fig. 33, D). At this stage and the onepreceding it SpJiccrocarpiis recalls the structure of the anther-idium of the Charace?e, although the succession of walls isnot exactly the same. The divisions of the central cells are ex-tremely regular, walls being formed at right angles, so thatthe sperm cells are almost perfectly cubical, and the limits ofthe primary central cells are recognisable for a long time. The development of the antheridial envelope begins muchearlier than that about the archegonium, but in exactly thesame way. By the time that the wall of the antheridium isformed the envelope has already grown up above its summit,and as the antheridium develops it extends far beyond it likea flask, at the bottom of which the antheridium is placed, andthrough whose neck the spermatozoids escape. These are A B £. Fig. 33.—Sphcerocarpus sp (?). Development of the antheridium. A-D, Median lon-gitudinal sections, X450; E, an older one, X22S, F, a spermatozoid, killed withosmic acid, X900. very much like those of the other Hepaticae, and in size exceedthose of most of the Marchantiaceae, but are smaller than isusual among the Jungermanniales. Leitgeb studied the germination of the spores in ^. tcrres-tris, which remain permanently united in tetrads. He foundthat 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 isfound at the end of which the young plant develops, one of theoctants 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 the6 §2 MOSSES AND FERNS CHAP. older plant. Leitgeb
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