. Carnegie Institution of Washington publication. 120 l II1 MAR VTT1 \ s equal parts (fig. 87, A). A rhizoid may be an of! either before or after this first transverse \\;< 11 is developed, but frequently no rhizoids are formed until a much later period, as in Ophioglossum. I hi- primar] rhizoid, when present, is formed much as in the typical ferns, the papilla from which it develops being cut off from the largei cell, and it contains little 01 no chlorophyll. I- ach of the primary prothal- lial cells divides, in typical casts, h\ a longitudinal wall, so that the young gameto- phyte cons
. Carnegie Institution of Washington publication. 120 l II1 MAR VTT1 \ s equal parts (fig. 87, A). A rhizoid may be an of! either before or after this first transverse \\;< 11 is developed, but frequently no rhizoids are formed until a much later period, as in Ophioglossum. I hi- primar] rhizoid, when present, is formed much as in the typical ferns, the papilla from which it develops being cut off from the largei cell, and it contains little 01 no chlorophyll. I- ach of the primary prothal- lial cells divides, in typical casts, h\ a longitudinal wall, so that the young gameto- phyte consists of four cells, arising quadrant-wise (fi<;. XX, A), and closely resembling corresponding stages 111 Ophioglossum, except for the absence of chlorophyll in the latter. Where the young plants are crowded or light is deficient, as for instance when the germination occurs within the sporangium, then- is a tendency to the development of a filament, a phenomenon often met with also in the typical ferns. Usually one of the upper pan of cells in the four-celled stage assumes the role of an apical cell, and for some time, as in the typical ferns, there is growth from a two-sided apical cell (fig. XX, C). As soon as the apical cell is established, it »rows. I 1,.. s \. Two germinating spores ol Marattia frax inea Smith. â 200. The remains oi the spore meml li. Young gametophyte ol ame 1 -;. (A,B,after Jonkmann). i . Marattia tambucina Blume. X I) II. Baker. 1)1', . 1.,-; 1;, H, x-,. G,H, show the young sporophytc. I) and E represent the same prothallium aftei an interval of about .1 pear. F 1^ tin- ventral riew of E. k, adventitious bud. very much as it does in such a liverwort as Aneura and produces a thallus of the same form and structure. But as the prothallium grows older a periclinal wall is formed in the apical cell, and in the outermost of the two cells thus produced there is a longitudinal wall dividing it into two equal cells, and from this time on i
Size: 2005px × 1246px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1911
