72 



MOSSES WITH A HAND-LENS 



known as teeth, as in Fig. 31, or of 

 a double row as in Fig. 43. In 

 the latter case the entire fringe is 

 still the peristome, but the term is 

 also applied in a particular sense 

 to the outer row ; the outer row is 

 often spoken of as the exostome 

 (b), and the inner as the endostome 

 (c). The inner row consists of as 

 many projections as the outer, but 

 alternating with them; these are 

 known as processes or segments 

 (c). Between the segments there 

 are often one or more slender hair- 

 like processes known as cilia. 

 (Fig. 43. d; fig. 36, c.) 



Moss peristomes, viewed with a 

 compound microscope, are among 

 the most beautiful of natural ob- 

 jects. They are not composed of 

 cells (except in the Polytrichaceae and a few other small families), 

 but of thickened cell walls. The cross markings on the teeth, 

 segments, and cilia are the lines of junction of the transverse cell 

 walls with the longitudinal cell walls forming the peristome. The 

 radial walls are rarely thickened so as to appear in any way ; the 

 divisural line shows the place of their attachment to the teeth and 

 segments. 



The researches of Philibert have shown that the endostome, 

 not the exostome, corresponds to the peristome of the mosses 

 having a single row of teeth. 



Processes, see under perist07ne. 

 Rost el late, (operculum) with a short beak. 

 Rostrate, (operculum) with a long beak. (Figs. 30 and 32.) 

 Rough, same as papillose. 

 Scabrous, same as papillose. 

 Segments, see under peristome. 



Seta, the stalk on which the capsule is borne. (Figs. 30, 35, 

 and 40. ) 



Sporangium, often applied to the capsule, but by some 

 authors restricted to the spore sac, or inner sac of the capsule 

 containing the spores. 



