. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. ISOETACEJE' SS7 rate the sporophylls of successive years, bears a single very large sporangium, situated upon the inner surface of the expanded base. According to Goebel (3) the young sporangium consists of an elongated elevation composed of cells which have divided by periclinal w^alls; but both Bower (15) and Smith (i) state that it can be traced back to a small group of strictly superficial cells which later undergo periclinal Fig. 322.—Isoetes echinospora. A, section of young s
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. ISOETACEJE' SS7 rate the sporophylls of successive years, bears a single very large sporangium, situated upon the inner surface of the expanded base. According to Goebel (3) the young sporangium consists of an elongated elevation composed of cells which have divided by periclinal w^alls; but both Bower (15) and Smith (i) state that it can be traced back to a small group of strictly superficial cells which later undergo periclinal Fig. 322.—Isoetes echinospora. A, section of young sporophyll, X32S; /, ligule; the sporangial cells have the nuclei shown. B, section of part of a young macro- sporangium, X32S; the sporogenous cells have the nuclei shown. C, cross-section of the base of a young sporophyll, with microsporangium, X25; v, the velum; vbj vascular bundle; the trabeculse are left unshaded. (After Wilson-Smith). The very complete account of the development of the spo- rangium of /. echinospora made by Wilson-Smith (i) differs in some important details from that of Goebel. The first peri- clinal division, while it may separate a definite parietal layer, does not, as a rule, do this; but there are further periclinal divisions in the superficial layer of cells which add to the spo- rogenous tissue, much as is the case in Equisetum and Ophio- glossum. There is not, therefore, the early and definite segre- gation of the archesporium described by Goebel, nor do the archesporial cells remain independent, as Goebel states is the case in /. lacustris. Wilson-Smith finds a complete absence of the regular. 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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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
