132 MOSSES AND LIVERWORTS 



for except in a few foreign species, where the 

 top of the capsule separates from the rest of 

 the capsule wall there is nothing to correspond 

 to the lid (operculum), which, as we have seen, 

 usually closes the mouth of a moss capsule (see 

 page 60) ; nor do we ever find anything in the 

 nature of the beautiful fringe of teeth (peri- 

 stome) which, in so many mosses, surrounds the 

 mouth of the capsule when the lid has fallen 

 off. As soon as the spores are ripe and ready to 

 hegin their life-work they are liberated by the 

 bursting of the capsule. Occasionally it opens 

 irregularly, as in certain species of moss ; very 

 rarely the capsule wall divides into two halves, 

 somewhat after the manner of a bean pod. But 

 in by far the greater number of cases it splits, 

 from top to bottom, into four pieces, which remain 

 attached by their lower ends to the top of the 

 fruit-stalk. Plate IX. fig. 12 gives a closed and 

 open capsule of one of the leafy liverworts, and 

 clearly illustrates the general mode of bursting 

 of the capsule wall, as above described. But 

 while in the large majority of cases there would 

 thus seem to be no similarity between the two 

 tribes in this matter of the opening of the cap- 

 sule, it is just here that we come across what 

 appears to be the most striking link between 

 them. 



I have already (p. 64) had occasion to refer, in 

 this connection, to that small group of mosses 



