294 



THE PERISTOME OF THE CAPSULE 



cells, known as the peristome, extends across the capsule and 

 becomes greatly thickened on its outer and usually on its inner 

 walls. This layer of cells is firmly attached to the walls of the 

 capsule by rather short thick-walled cells (Figs. 210, 3, p; 211, 

 6-8, p). When the spores are mature, the more delicate cells 

 break down, leaving little more than a loose mass of spores and 

 the peristome within the capsule. The cells of the peristome 

 break apart into teeth-like segments (Fig. 211, 7) and being 



Fig. 212. Germination of the spore: 3, early stage in the germination. 

 4, character of the branching, alga-Uke filaments that are finally developed 

 from the spore — r, rhizoids which penetrate the ground; h, bud which will 

 develop into a leafy moss plant. 



very hygroscopic, cooperate with the contracting capsule in forc- 

 ing off the operculum. After the removal of the operculum the 

 mouth of the capsule is covered by the peristome which now ap- 

 pears as a fringe of teeth radiating out from the walls of the 

 capsule (Fig. 210, 4). The teeth of the peristome are always in 

 multiples of two and form one or more, usually two layers, ac- 

 cordingly as only the outer or both surfaces of the peristome cells 

 are thickened. These teeth are so variously marked and fash- 

 ioned that they furnish one of the most characteristic features 

 of the various genera of the mosses. The peristome closes the 



