in 



THE JUNGERMANNIALES 



95 



cells, each composed of four equal quadrant cells. According 

 to Leitgeb (i), the upper tier, from which the capsule develops, 

 is formed by the first transverse wall in the up])er part of the 

 embryo. This upper tier is next divided by nearly transverse 

 walls into four terminal cover cells, and four larger ones below, 

 and these latter are again divided each into three cells, an inner 

 one and two outer ones, so that the capsule consists of four 

 central cells, the archesporium, and twelve wall cells (Fig. 45, 

 A). A similar division in the lower tiers results in the forma- 

 tion of four axial rows and a single outside layer of cells in 

 the stalk. In the lowest tiers the divisions are much less regu- 

 lar, and the foot, which is not very largely developed, shows 



A 



Fig. 45.^A, Young embryo of Aneura midtifida, optical section, X235 (after Leit- 

 geb); B, median longitudinal section of an older sporogonium of A. pingnis, X35\ 

 C, upper part of B, X200; sp, sporogenous cells; el, young elater,s; m, apical group 

 of sterile cells. 



no definite arrangement of the cells. The part of the wall of 

 the capsule formed from the four cover cells later become two- 

 layered, but the rest remains but one cell thick. In Metzgcria 

 (Leitgeb (7), III.) the wall becomes later two-layered. The 

 archesporium divides first into two layers. In the upper 

 cells the divisions are more regular than in the lower one, 

 and later the archesporium is made up of cells arranged in 

 more or less regular lines, starting from just below the apex 

 and radiating from this point, extending to the base of the 

 capsule. These cells are at first of similar form, and with 



