. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 169 fusion of cells and not by a splitting apart of the cells and the development of secreting cells about this intercellular space. In his earlier paper Brebner states that the mucilage ducts are schizogenous, but in his later paper he admits that they may be of lysigenous origin, which certainly is the case in the species of Dancea described here. The details of the older central bundles of the sections F and G, fig. 150, are shown in fig. 153, E, F; the shaded cells in C are tannin cells. Figure 151 shows longitudinal se
. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 169 fusion of cells and not by a splitting apart of the cells and the development of secreting cells about this intercellular space. In his earlier paper Brebner states that the mucilage ducts are schizogenous, but in his later paper he admits that they may be of lysigenous origin, which certainly is the case in the species of Dancea described here. The details of the older central bundles of the sections F and G, fig. 150, are shown in fig. 153, E, F; the shaded cells in C are tannin cells. Figure 151 shows longitudinal sections of a young sporophyte of D. ellipiica, of about the same age as the sporophyte which has just been described. This also shows three fully developed leaves, while the fourth and fifth leaves are well Fig. 1 J3. Details of the vascular system of sporophyte shown in fig. 150. A. Passes through the stem apex; B and C, lower down, showing the fourth and fifth leaf traces. X150. D. A single leaf trace. X 150. E, F. Vascular bundles from the lower part of the stem, m, m, young mucilage ducts. The central bundle of the stem formed by the junction of the three first leaf traces is now conspicuous and forms a stout central strand, continuing downward into the primary root (r1). A is a nearly median section, passing through the stem apex, whose large and conspicuous apical cell is shown in fig. 152, B. I he apex of the fifth leaf is seen just above this and a more enlarged figure of this is shown in fig. 152, A. The apex of the fifth leaf (which is here cut transversely) is occupied by a small group of large cells, of which the central one may perhaps represent a single initial cell. Below the stem apex, but separated from it by a considerable amount of tissue, can be seen the bases of the leaf trans from the fourth and fifth leaves respectively. These are joining the central bundle of the stem near the junction. Please note that these images are extracted from scanned p
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