The structure & development of the mosses and ferns (Archegoniatae) . d vertical division walls in the central cells alter-nate with great regularity, so that there is little displacementof the cells, and up to the time of the separation of the spermcells the four primary divisions are still plainly discernible, andthe individual sperm cells are cubical in form. In the peri-pheral cells hardly less regularity is observable. Except near 1 Leitgeb (7), vol. v. p. 17. 124 MOSSES AND FERNS CHAP. the apex none but radial walls are formed after the first trans-verse wall has divided the body of the
The structure & development of the mosses and ferns (Archegoniatae) . d vertical division walls in the central cells alter-nate with great regularity, so that there is little displacementof the cells, and up to the time of the separation of the spermcells the four primary divisions are still plainly discernible, andthe individual sperm cells are cubical in form. In the peri-pheral cells hardly less regularity is observable. Except near 1 Leitgeb (7), vol. v. p. 17. 124 MOSSES AND FERNS CHAP. the apex none but radial walls are formed after the first trans-verse wall has divided the body of the antheridium into twotiers, and when complete the wall consists of three well-markedtransverse rows of cells, the lower being derived from the upper-most tier of stalk cells. At the apex the cells are not quite soregular (Figs. D, E). In its younger stages the antheridiumis very transparent and perfectly colourless. In each peripheralcell a chloroplast is evident, but at this stage it is quite colour-less and the nucleus is very easily seen in close contact with Fig. 58.—Ajithoccros fusifor7nis (Aust.)- Development of the antheridium ; D, E, drawn fromliving specimens, the others microtome sections; D, t, shows the single chloropla-st in each of thewall cells;_and the secondary antheridium (s) budding out from its base ; 2 is an optical sectionof the same ; E, surface view of fuU-gi^own antheridium ; F, cross-section of a younger one. , E X225, the others X450. As the antheridium grows the chloroplasts develop with it,becoming much larger and elongated in shape, and at the sametime develop chlorophyll. The mature chloroplast is a flattenedplate that nearly covers one side of the cell, and its colour haschanged from green to a bright orange as in the antheridiumof many Mosses. The sperm cells are discharged through anopening formed by the separation of the apical cells of theantheridium. These cells do not become detached, and returnto their original position, so tha
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