MOSSES. 



333 



hygronietrica symmetrically, corresponding to the part in Fig. 245, C, designated a ; 

 ^ ^ is the reddish-brown epidermis strongly thickened on the outside ; at the part where 

 it bulges its cells are of a peculiar shape, forming the ring or annulus ; se is the tissue 



Fig 250. — Futt.tria hy^rotnetrica ; part of a longitudinal 

 section of an unripe theca. 



Fig. I'^x.—Funaria hygronietrica ; part of a transverse section 

 through the operculum. 



FIG. 252.—^ longitudinal section of the theca of Poly- 

 trichum piliferunt (after Lantzius-Beninga, X15) ! B the 

 transverse section (x about s) ; ™ wall of the theca, cii 

 operculum, c c columella, p peristome, ep epiphragm, a a 

 annulus, i t the air-cavities penetrated by alga-like cel- 

 lular filaments, s spore-sac, containing the primary mother- 

 cells of the spores, st the seta, the upper part of which 

 forms the apophysis ap. 



lying between the epidermis of the theca and the air-cavity h ; the large-celled tissue p 

 is the prolongation of the columella within the cavity of the operculum ; at S are seen 

 the uppermost spore-mother-cells ; directly above the air-cavity h rises the layer of cells 



