82 



times necessary to make a microscojDic examination in order to 



make sure. 



In the young pro thallium there is often developed a single 

 two-sided apical cell as in most other ferns. There is a strong 

 tendency to the formation of a solid cell])ody at first in many 

 cases. While the young prothallium is nsually smooth in out- 

 line, the older ones usually show more or less conspicuous 

 lobing of the margins such as is found to a greater or less 

 extent in the large prothallia of all species. 



Of the four species studied by the writer only one, G: pol^- 

 podioides Sm., belongs to the section Eugleichenia, the others 

 belonging to the section Mertensia Willd. (=-- Dicranopteris Bernh.). 

 The prothallia of the former were collected on the lower slope 

 of Table Mountain not far from Capetown, and thanks are due 

 to Professor H. H. W. Pearson, who took me to the place 

 where the ferns grew. The prothallia were found in crevices 

 of the ledges where the sporophyte was growing, and although 

 the number obtained was not very large, it was sufficient to 

 show the structure of the prothallium itself and the reproduc- 

 tive organs. The prothallium is this species (PI. IX, Figs. 38,41 

 and 42) is much broader relatively than that of the other species 

 studied and resembles more nearly that of the t3^pical Poly- 

 podiaceae. The archegonial cushion or midrib, however, is often 

 very massive and develops very early. The margin of the pro- 

 thallium is nearly smooth and the leaf-like lobes characterizing 

 the other species are almost entirely absent. The stiff brown 

 rhizoids are conspicuous. The prothallia of other species were 

 found upon banks beneath overhanging masses of the spore- 

 bearing [)lants. In all three species, i. e. (r. dichotoma, G. pec- 

 tinatii and (r. laevit/nta, the elongated form of the prothallium 

 is marked except in the very youngest stages, and in all of 

 them the formation of the leaf-like marginal lobes is more or 

 less striking. As Rauwkntioef found in some of the species 

 studied by him (loc. cit., p. 40), all species showed a tendency 

 to produce very large prothallia, which, for some imexplained 

 reason, do not produce embryos, although archegonia are pre- 



