. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VII PTERIDOPHYTA—FILICINEM—OPHIOGLOSSACE^ 255 arate an inner archesporium from the outer cells, destined to form the wall of the sporangium. Between the young spo- rangia the cells form sterile septa. The cell-groups which form archesporia, and those which develop into sterile septa, are sister-cell groups. All of the sporogenous tissue cannot be traced back to the primary archesporial cell, as later secondary sporogenous tissue may be formed by further periclinal divisions in the outer cells
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VII PTERIDOPHYTA—FILICINEM—OPHIOGLOSSACE^ 255 arate an inner archesporium from the outer cells, destined to form the wall of the sporangium. Between the young spo- rangia the cells form sterile septa. The cell-groups which form archesporia, and those which develop into sterile septa, are sister-cell groups. All of the sporogenous tissue cannot be traced back to the primary archesporial cell, as later secondary sporogenous tissue may be formed by further periclinal divisions in the outer cells of the sporangium. A transverse section of the very young sporangiophore is. Fig. 139.—^A, Very young; B, older sporangia of O. pendulum; transverse sections, X260. somewhat triangular, the broader side corresponding to the outer surface of the sporangiophore. The cells are very irreg- ular in form, and no differentiation of the tissues is to be observed. Sections of somewhat older stages show in some cases, at least, a large epidermal cell occupying nearly the centre of the shorter sides of the triangular section. This cell has a larger nucleus than its neighbours, and is decidedly broader. The next stage was not observed, but a somewhat more advanced one shows a small group of inner cells (shaded in the figure), which appear to have arisen from the 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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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
