. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 6o MOSSES AND FERNS CHAP. capsule, which in Boschia at maturity develops upon the inner cell walls thickened bars. Only a portion of the cells of the central part produce spores; the remainder do not divide after the spore mother cells are formed, but remain either as simple slightly elongated nourishing cells (Corsinia) or elaters (Boschia). The other Marchantiacese are much alike, and as Targionia was found to be an especially satisfactory forni for study, on account of the readiness with wh
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 6o MOSSES AND FERNS CHAP. capsule, which in Boschia at maturity develops upon the inner cell walls thickened bars. Only a portion of the cells of the central part produce spores; the remainder do not divide after the spore mother cells are formed, but remain either as simple slightly elongated nourishing cells (Corsinia) or elaters (Boschia). The other Marchantiacese are much alike, and as Targionia was found to be an especially satisfactory forni for study, on account of the readiness with which straight sections of the embryo could be made, it was taken as a type of the higher Marchantiales. The first division wall (basal wall) is trans- verse, and divides the embryo into two nearly equal parts. This is followed in both halves by nearly vertical walls (quadrant walls), and these and the basal wall are then bisected by the octant walls, so that as in Riccia the young embryo is formed of eight nearly equal cells. In Targionia, even at this period, the embryo is always somewhat elongated instead of globular. The next division walls vary a good deal in different individuals. Fig. 23, C shows a very regular arrangement of cells, where the first divisions were much the same in all the quadrants. Here all the secondary walls were nearly parallel with the basal wall, and intersected the quadrant and octant walls; but quite as often, especially in the upper half of the embryo, these secondary walls may intersect the basal wall. In no cases seen was there any indication of a two-sided apical cell such as Hofmeister figures for Tar- sia. 22.—Corsinia march an- . , - ^, , . tioides. Young sporogo- gioHta, and probably his error arose nium, optical section. X300 from a study of forms where the quad- " ^^ ' rant walls were somewhat inclined, in which case the intersection of one of the secondary walls with it might cause the apex of the embryo to be occupied by a cell th
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
