m 



THE JUNGERMANNIALES 



97 



brought about by a periclinal wall in each of the four terminal 

 cells, dividing each into an inner archesporial cell, and an 

 outer wall-cell. (Fig. 47, D.) 



The capsule wall in Fossomhronia is two cells in thickness, 

 except at the apex, where it may be three cells thick. The 

 inner layer of cells, when the capsule is ripe, have irregular 

 thickened bars developed upon the surface of the radial cell- 

 walls. 



The development of the sporogonium is best known in 

 Pellia epiphylla (Kienitz-Gerloff (i), Hofmeister (i) ). Here 

 the first wall, as in Aneura, separates a lower cell, which sim- 

 ply forms an appendage, from the upper cell, from which the 



B. 



Fig. 47. — Fossomhronia longiseta. Development of the embryo, X525; B, E, cross- 

 sections; D, shows one of the primary archesporial cells. Figures drawn by 

 Mr. H. B. Humphrey. 



stalk and capsule develop. In the latter the first wall is ver- 

 tical, and is followed in each of the resulting cells by horizontal 

 walls, by which the separation of the capsule from the seta is 

 effected. These four cells are now divided by vertical walls, 

 so that two layers of four cells each are present. The first 

 periclinal walls in the apical group of cells separate the arch- 

 esporium from the wall of the capsule. 



