. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 256 MOSSES AND FERNS CHAP. cell by a transverse wall, although this point is exceedingly difficult to determine on account of the great similarity of all the cells (Fig. 139). This group of inner cells (or the single one from which they perhaps come) constitutes the arche- sporium, and by rapid division in all directions forms a large mass of cells whose contents become denser than those of the. Fig. 140.—Ophioglossum pendulum. A, Section of a young sporangium, the arch* esporial tissue is sli
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 256 MOSSES AND FERNS CHAP. cell by a transverse wall, although this point is exceedingly difficult to determine on account of the great similarity of all the cells (Fig. 139). This group of inner cells (or the single one from which they perhaps come) constitutes the arche- sporium, and by rapid division in all directions forms a large mass of cells whose contents become denser than those of the. Fig. 140.—Ophioglossum pendulum. A, Section of a young sporangium, the arch* esporial tissue is sliaded, the inner cells with dark nuclei being the definitive sporogenous cells, X200; B, transverse section of an older sporangium; sp, sporangeous cells; t, tapetum, X about 35; C, a portion of B more highly magni- fied; D, section of nearly mature sporangial spike, X8. surrounding ones, between which and these, however, the limits are not very plain. Later, when the number of cells is com- plete, the difference between them and the sterile tissue of the sporangiophore is much more evident. The cells lying outside of the archesporium divide rapidly both by longitudinal and transverse walls, and form the thick outer wall of the sporangium. In longitudinal sections, two. 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, Douglas Houghton, 1859-1953. New York, The Macmillan Company;
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