234 



BOTANY 



has the cells forming its margin much thickened. Above these is a ring of 

 large, thin- walled cells, the Annulus, which finally are destroyed, and effect the 

 separation of the operculum from the theca. 



B. 



i. 



FIG. 197. Funaria hygrometrica. A, longitudinal section of a nearly ripe capsule 

 (X 200) ; per, peristome ; r, annulus; t, thickened cells forming the rim of the 

 theca. B, sporogenous cells, shortly before the final division (x 400) ; i, inner, 

 o, outer, spore-sac. C, longitudinal section of a mature capsule (x 30) ; s, seta; 

 a, apophysis ; sp, spores ; col, columella ; r, annulus ; o, operculum. 



Beneath the operculum there are developed, in most Bryales, the 

 peculiar structures forming the "Peristome." The peristome is 

 usually composed of the remains of the thickened cell-walls of special 

 cells, which are separated from the wall of the operculum by two or 

 three layers of thin-walled cells which wither away as the capsule 

 ripens. The peristome usually has the form of teeth fringing the 

 margin of the theca. These generally are in two rows, representing 



