374 



FRUCTIFICATION OF MOSSES : PERISTOME. 



at length tears across the walls of the flask-shaped archegonium 

 by a circular fissure, carrying the higher part upwards as a Calyptra 



or Hood (Fig. 

 Fig. 184. 182, B, c) upon 



its summit, 

 while the lower 

 part remains to 

 form a kind of 

 collar round the 

 base of the stalk. 

 277. The Urns 

 or Spore - Cap- 

 sules of Mosses, 

 which are thus 

 the immediate 

 product of the 

 Generative act, 

 and which must 

 really be con- 

 sidered as the 

 offspring of the 

 plants that bear 

 them (although 

 grafted on to these, and drawing their nourishment from them), 

 are closed at their summit by Opercida or lids (Fig. 182, b, o, o), 

 which fall off when the contents of the capsules are mature, so as 

 to give them free exit ; and the mouth thus laid open is sur- 

 rounded by a beautiful toothed 



Mouth of Capsule of Funaria, showing the 

 Peristome in situ. 



Fig. 185. 



fringe, which is termed the 

 Peristome. This fringe, as seen 

 in its original undisturbed posi- 

 tion, is shown in Fig. 184, and 

 is a beautiful object for the 

 Binocular Microscope ; it is very 

 hygrometric, executing when 

 breathed on a curious move- 

 ment, which is probably con- 

 cerned in the dispersion of the 

 spores. In Figs. 185-187 are 

 shown three different forms of 

 Peristome, spread out and de- 

 tached, illustrating the varieties 

 which it exhibits in different 

 genera of Mosses, — varieties 

 whose existence and readiness 

 of recognition render them 

 characters of extreme value to the systematic Botanist, whilst they 

 furnish objects of great interest and beauty for the Microscopist. 

 The Peristome seems always to be originally double, one layer 



Double Peristome of Fontinalis 

 antijpyretica. 



