CHAP, VII 



THE BRYINE.-E 



207 



which Hke that of Funaria has the form of a hollow cylinder 

 through which the columella passes. Between the outer 

 spore-sac and the wall of the sporogonium an intercellular 

 space is also formed, but the separation of the cells is 

 complete, and there are no filaments connecting the spore-sac 

 and the sporogonium wall as in Funaria. The cells of the 

 archesporium are few in number and correspondingly large 

 (Fig. 103, E), and before the division into the spores takes 

 place all the central tissue of the columella is absorbed, and 

 the spore mother cells occupy the whole central space. Here 

 the division of the spores is completed, and at maturity the 

 whole of the capsule is filled with 

 the large spores, and no trace of the 

 columella remains. 



The highest members of the 

 Cleistocarpae, such as Phascum and 

 Pleuridiiun (Fig. 104), approach 

 very closely in structure the stego- 

 carpous Bryineae. In these the 

 gametophore is much better devel- 

 oped than in Ephemerum, and the 

 protonema not so conspicuous. The 

 leaves also frequently have a well- 

 developed midrib which is wanting 

 in the leaves of EpJiemeriim. 



Kienitz - Gerloff ^ has carefully 

 studied the embryogeny of Phascum 

 cuspidatuvi, and except in a few 



minor details it corresponds very closely to that of Funaria, ex- 

 cept, of course, as regards the operculum and peristome, which 

 are absent. In Phascum, however, the archesporium is differen- 

 tiated earlier than in Funaria. In each of the four primary cells 

 of the endothecium, as seen in transverse section, a periclinal 

 wall arises which at once separates the archesporium from the 

 columella (Fig. 103, D). The outer spore-sac has but two 

 layers of cells, and the capsule wall three, and between them 

 the large lacuna is formed as in Funaria ; but in Phascum as 

 in EpJiemerum, the separation of the cells is complete. In the 

 seta a slightly-developed central cylinder of conducting tissue 

 is developed, derived, as in Funaria, from the endothecium, 



1 Kienitz-Gerloff (2). 



Fig. 104. — Plciiridium siihulatuin, X 20. 



