. The structure and development of mosses and ferns (Archegoniatae). corre-spond closely in origin and structure to the other Bryales. Thedevelopment of the sporogonium in its early phases is also thesame, and the differences only appear at a late stage. Theseparation of endothecium and amphithecium is apparently ex-actly the same as in other Bryales, and from the former is de-rived the archesporium, which like that of Funaria has the formof a hollow cylinder through which the columella passes. Be-tween, the outer spore-sac and the wall of the sporogonium anintercellular space is also formed,
. The structure and development of mosses and ferns (Archegoniatae). corre-spond closely in origin and structure to the other Bryales. Thedevelopment of the sporogonium in its early phases is also thesame, and the differences only appear at a late stage. Theseparation of endothecium and amphithecium is apparently ex-actly the same as in other Bryales, and from the former is de-rived the archesporium, which like that of Funaria has the formof a hollow cylinder through which the columella passes. Be-tween, the outer spore-sac and the wall of the sporogonium anintercellular space is also formed, but the separation of the cellsis complete, and there are no filaments connecting the spore-sacand the sporogonium wall as in Funaria. The cells of thearchesporium are few in number and correspondingly large(Fig 115, E), and before the division into the spores takesplace all the central tissue of the columella is absorbed, andthe spore mother cells occupy the whole central space, wherethe division of the spores is completed, and at maturity the VI. THE BRYALES 21. Fig. 115.—A, Longitudinal section of the young sporogonium of Pleuridium subulatum,X8o; B, part of the same, X600; sp, archesporium; C, young embryo of Phasciimcuspidatum, optical section, X17S; D, cross-section of an older embryo of thesame, X350; sp, archesporium; E, longitudinal section of the central part of theyoung sporogonium of Ephemerum pliascoides, X350; sp, archesporium. C, D,after Kienitz-Gerloff; E, after MuUer. 2l6 MOSSES AND FERNS CHAP. whole of the capsule is filled with the large spores, and no traceof the columella remains. Nanomitrium (Goebel (22), p. 374), closely resemblesEphemerum in the development of the sporophyte. The highest members of the Cleistocarpse, such as Phascumand Pleiiridhim (Fig. 116), approach very closely in structurethe stegocarpous Bryales. In these the gametophore is muchbetter developed than in Ephemerum, and the protonema notso conspicuous. The leaves also frequently have
Size: 1270px × 1968px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
