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 Marchantiaceae are much alike, and as Targionia 

 was found to be an especially satisfactory form 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 paralkd? 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- 

 gionia, and probably his error arose 

 X3oo 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 

 that, in section, would appear like the two-sided apical cell of 

 the Moss embryo. The regular formation of octants was ob- 

 served by me in Fimbriaria Calif ornica, and by Kienitz-Gerloff 



FIG. 22. Corsinia march an 

 tioides. Young s p o r o g o 

 nium, optical section. 

 (Leitgeb). 



