m THE JUNGERMANNIALES m 



Both longitudinal and transverse sections of the sporogonium 

 at this stage (Fig. 55, D) show a good deal of irregularity in 

 the arrangement of the cells, and the first periclinal walls form 

 at very different distances from the surface, so that it is clear 

 that the wall cannot be established, as in Radula for instance, 

 by the first periclinals. 



The cells of the older archesporium are arranged in more 

 or less evident rows radiating from the base (Fig. 56, A). 

 No definite relation of spores and elaters can be made out, the 

 two sorts of cells being mingled apparently without any regu- 

 lar order. Some of the cells cease dividing and grow regu- 

 larly in all directions, while others may divide further and 

 grow mainly in the plane of division, so that they become 

 elongated. The former are the young spore mother cells, the 

 latter the elaters (Fig. 56, C). The division of the spores 

 begins while the cells of the archesporium are still united, 

 although at this time the swollen and strongly striated cell 

 walls of the mother cells (Fig. 56, C) show that they are be- 

 coming mucilaginous. At this stage sections through the 

 archesporium show the deeply-lobed spore mother cells with 

 the elongated elaters packed in between them, the pointed ends 

 of the latter fitting into the interstices between the spore 

 mother cells. The latter are somewhat angular and the wall 

 distinctly striated. It is the inner layer only of the wall that 

 projects into the cavity of the cell and forms the characteristic 

 lobes marking the position of the four spores. The cell cavity 

 is filled with crowded granules, some of which are chloroplasts. 

 The nucleus, which is of moderate size, and rich in chromatin, 

 has a distinct nucleolus. The elaters have thinner walls than 

 the spore mother cells, and the contents are more finely granu- 

 lar. A distinct nucleus staining strongly with the usual 

 reagents is present. The further history of spores and elaters 

 corresponds closely with that of the forms already described. 

 The ripe spores have only a thin wall, which is coloured brown, 

 and has delicate granular thickenings. 



In a paper by Le Clerc du Sablon (3) the statement is 

 made, and figures are given, showing that at an early stage in 

 the development of the spores and elaters of a number of He- 

 paticse the walls of the cells are completely destroyed, so that 

 the young spore .mother cells and elaters are primordial cells. 

 A great many carefully stained microtome sections of a large 



