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, £, F; the shaded cells in C are tannin cells. 



Figure 151 shows longitudinal sections of a young sporophyte of D. elltptica, 

 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 advanced. 



Fig. 153. — 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. X150. 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 (r'). A is z nearly median section, passing through the stem apex, 

 whose large and conspicuous apical cell is shown in fig. 152, B. The apex of the 

 fifth leaf is seen just above this and a more enlarged figure of this is shown in fig. 

 152, J. 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 traces from the fourth and fifth leaves 

 respectively. These are joining the central bundle of the stem near the junction 



