. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. X THE HOMOSPOROUS LEPTOSPORANGIAT^ 357 As in Onoclea the primary organs are established by the first two walls, and the next divisions form octants, but there is somewhat less regularity in the later divisions, in which respect Osmunda is intermediate between the Polypodiacese and the Eusporangiatse. As in the former, the two epibasal quadrants develop stem and cotyledon, the hypobasal ones, root and foot. At this stage the cells of the young embryo contain but little granular cytoplasm, and t
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. X THE HOMOSPOROUS LEPTOSPORANGIAT^ 357 As in Onoclea the primary organs are established by the first two walls, and the next divisions form octants, but there is somewhat less regularity in the later divisions, in which respect Osmunda is intermediate between the Polypodiacese and the Eusporangiatse. As in the former, the two epibasal quadrants develop stem and cotyledon, the hypobasal ones, root and foot. At this stage the cells of the young embryo contain but little granular cytoplasm, and there are large vacuoles. As the embryo grows older the granular cell contents increase in quan- tity. The subsequent divisions follow very closely those in the embryo of Onoclea, but are less regular, and the embryo retains for a longer time its original nearly globular Fig. 199.—Three sections of one embryo of O. cinnamomea in whicli tlie root (r) is especially well marked, X260. Lettering as in the last. The direction of growth of the cotyledon is determined in part by the first walls in its primary octants. The outer octant usually becomes at once its apical cell, and if its first segment is formed on the side next the octant wall, this throws the axis of growth very much to one side, so that the axis of the, leaf, may be almost at right angles to the median line of the embryo. Otherwise it nearly coincides with this. The original three- sided apical cell persists for a long time, and it could not be positively shown whether or not it was afterwards replaced by. 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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