BRYOPHYTA. 



703 



away the spores are ripe, and the columella, &c., have dried up and collapsed. The 

 teeth of the peristome are exceedingly varied in pattern in the various genera of 

 Mosses ; typically there are two series of them forming an outer and an inner peri- 

 stome (cf. fig. 397 9 ), but they are differently thickened, fused, and divided, and one 

 or even both series (e.g. Gymnostomum), may be absent. They are very hygro- 

 scopic, and their function will be alluded to later on when we are discussing the 



10 



Fig. 399. Spore-capsules of Mosses. 



1 Splachnum luteum. 2 An unripe capsule of the same. ' A ripe and open capsule of the same. * Splachnum vasculosum. 

 6 Longitudinal section of a ripe capsule of this moss, showing the large apophysis below containing lacunae, and traversed 

 in the middle by the columella; above is the capsule proper with persistent columella, spore-sac, and peristome. 

 Splachnum ampullaceum. 7 An unripe capsule. A ripe capsule of the same. and w Schistostega osmundacea. 

 11 A ripe capsule of the same. 1, , , " natural size ; a, x 2 ; *, , x 10 ; " x 15 ; x 100. 



distribution of spores. In the Polytricheae the peristome is not quite the same as in 

 other Mosses. In this group the teeth are very numerous and quite short, and from 

 their apices a membrane (the epiphragm) remains stretched after the fall of the lid 

 {cf. fig. 397 4 ). The spores here tumble out between the teeth. 



The position of the sporogonium is of course determined by that of the female 

 "flowers"; where these are terminal the sporogonium will be terminal (acrocarpous), 

 -similarly where lateral (pleurocarpous). The number of genera of Bryacese is so 



