VI. 



THE BRYALES 



205 



be first divided by a median wall into two equal cells. In 

 Fiinaria usually the next division wall is periclinal, and at once 

 separates endothecium and amphithecium. In most other 

 Bryineae that have been examined, however, and this may also 

 occur in Fimaria (see Fig. 107, A), the second walls formed in 

 the young segments are anticlinal, and it is not until the third 

 set of walls is formed that the separation of endothecium and 

 amphithecium is complete. The next divisions (Fig. 107, C), 

 are in the amphithecium, and separate it into two layers. In 

 the endothecium a series of walls is next formed, almost exactly 

 repeating the first divisions in the original segment (Figs. D, 



N 



Fig. 107. — Five transverse sections of a young embryo of F. hygrometrica. A, Just 

 below the apex, the others successively lower down; en, endothecium, X450' . 



E), and transforming it into a group of four central cells and 

 eight peripheral ones. Each of the latter divides twice by in- 

 tersecting walls, so that a group of about sixteen cells (Fig. 

 108, A), occupies the middle of the endothecium. The eight 

 peripheral cells divide by radial walls, after which each of these 

 cells is divided by a periclinal wall into an outer and an inner 

 cell (Fig. 108, B), and the outer cells divide rapidly by radial 

 walls and form the archesporium. The single layer of cells 

 immediately within, and therefore sister cells of the primary 

 archesporial ones, is the inner spore-sac. 



The account of the development of the endothecium here 

 given differs slightly from the account of Kienitz-Gerloff (2), 



