HuTTON. — On Modifications in Ca])sules of Mosses. 343 



fruit-stalk is sometimes straight, but often curved, so that the capsule is 

 inclined or pendulous (fig. 13), with the mouth turned downward and thus 

 protected from rain. . In some mosses the same effect is obtained by the 

 capsule itself being cernuous, while the fruit-stalk is straight. 



In order to give some method to the remarks that follow I shall divide the 

 mosses into (1) those in which the capsule alone is used ; (2) those in which 

 the peristome is used ; and (3) those in which the columella is used, combined 

 either with the operculum or with the peristome. 



1. Mosses in which the capsule alone is used. 



In the lowest forms, the family Phascei, the capsule decays and bursts 

 open irregularly so that the spores are quite exposed, except in those species 

 where the capsule is immersed in the perichsetial leaves. But it must be 

 remarked that in Phascum cuspidatum, which is the only species in which I 

 have been able to make the observation, the perichsetial leaves open when wet 

 and close when dry, so that the protection thus afforded can be but slight. 

 They have, however, very few spores in a capsule, Phascum alternifolium only 

 having about sixteen, and P, serratum about one hundred, so that it would 

 hardly be necessary to protect so few from being all blown away together. 

 These mosses are all inhabitants of the plains, and grow on ditch banks and 

 other sheltered situations j but there is another family, the Andreoiece, which 

 lives on exposed rocks on mountains, and yet has the capsule not much more 

 complicated than in the humble Phascei. In this family when the spores are 

 ripe the capsule divides longitudinally into four or more parts, the upper 

 extremities of which adhere together. These parts bend downward when dry, 

 and allow the spores to escape through the open fissures (fig. 86), but on the 

 air getting damp they straighten and close up the capsule again quite tight 

 (fig. ^a), and thus prevent the spores being blown away in wet weather. 



The first step towards a more complicated state of things is when the 

 capsule, instead of bursting through decay, is furnished with an operculum, 

 which falls off when the spores are ripe, thus leaving them to some extent 

 protected by the vase-like form of the capsule. Some genera of mosses, such 

 as Braunia, Physcomitrium, and Aulacopilum, have no further provision 

 against all their spores being knocked out at once ] but in others, as Hedwigia 

 and Leptangium,'^ the capsule is immersed in the leaves. In the genus 

 Sjjhagnum, when the capsule is ripe, the operculum and spores are said to be 

 driven off with violence to a distance of six or seven inches. The next step is 

 the formation of a flexible ring of very hygroscopic cells, called the annulus (fig. 

 14), interposed between the mouth of the capsule and the operculum, as in 

 (Enectangium and Galomnion, which protects in some measure the spores from 



* Leptangium is said by Dr. Hooker to have the mouth of the capsule closed lq by a 

 membrane. I have had no opportunity of examining it personally. 



