. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 322 MOSSES AND FERNS CHAP. embryo into the anterior epibasal half and the posterior hypo- basal. The former produces the stem and cotyledon, the latter the primary root and foot. The early divisions are extremely regular, and offer a marked contrast to those in the eusporangiate embryo. The second wall is the transverse (quadrant) wall, separating the leaf and stem in the epibasal part, and the root and foot in the hypobasal. The next walls are the median or octant walls, but they do not corre
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 322 MOSSES AND FERNS CHAP. embryo into the anterior epibasal half and the posterior hypo- basal. The former produces the stem and cotyledon, the latter the primary root and foot. The early divisions are extremely regular, and offer a marked contrast to those in the eusporangiate embryo. The second wall is the transverse (quadrant) wall, separating the leaf and stem in the epibasal part, and the root and foot in the hypobasal. The next walls are the median or octant walls, but they do not correspond. Fig. 178.—Onoclea sensibilis. A, two-celled embryo, X about 500; B, an eight-celled embryo, longitudinal section; C, two longitudinal sections of an older embryo, X about 250; D, E, two horizontal sections of a still older embryo; F, longitudinal section of an advanced embryo; the cotyledon is beginning to project beyond the other organs; cot, cotyledon; r, root; st, stem; f, foot. (All figures drawn from sections made by Dr. W. R. Shaw.) exactly in all the quadrants. While in the cotyledon and stem they are almost exactly median, in the root especially, the octant wall diverges often a good deal from the median line, and the two resulting octants are unequal in size. The following divisions correspond for a short time in all the octants, but soon show characteristic differences. For a short time each octant shows a definite apical growth, the segments being cut off by walls formed successively parallel to the three primary. 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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