xii INTRODUCTION. 



fructification advances, separates transversely at the bottom, and 

 rising up with the more advanced germen, takes the name of 

 Calyptra, or veil. It is carried up by means of a pedicel, or fruit- 

 stalk, which now develops itself, and reaches to a different height 

 in different species ; in some, being five or six inches in length. 

 When it lias attained its utmost development, the mature germen 

 becomes the perfect fruit, and is called the Capsule. The Calyp- 

 tra, with its acuminated persistent style, drops off spontaneously, 

 and exposes to view, on the top of the capsule, a lid, or opercu- 

 lum, which is variously shaped in different individuals, sometimes 

 being almost plane, sometimes conical, sometimes subulate. This, 

 in time, likewise, in almost every instance, falling away, exposes 

 the mouth of the capsule, which affords some of the most important 

 marks of distinction in the several genera of Mosses. In some, the 

 mouth is quite naked ; in others, it is furnished with a most beauti- 

 ful and curious apparatus of teeth-like processes, or sometimes 

 membranes, which some call a fringe, or peristome, and these are 

 variously cut at the extremity. These processes sometimes form 

 a single row about the mouth, and then it is called a "peristomium 

 simplex" or the row is double, whence the term "peristomium 

 duplex? 



Externally, at the base of the capsule, there is frequently a 

 swelling of a different substance from the capsule itself; this is 

 called the apophysis. 



The Capsule, when ripe, is more or less of a horny, or cartila- 

 ginous substance, extremely variable in form ; ovate, as in most 

 Mosses ; sphserical, as in some species of Phascum and Bartra- 

 mia ; quadrangular in some Polytricha ; pyriform, or pear-shaped 

 in Funaria ; oblique and gibbous beneath, and plane on the top, 

 in Buxbaumia. It is smooth in the generality of Mosses ; 

 striated, sulcated, or dotted in others. In the inside is a mem- 

 branous bag, (or inner membrane, as it is called;) from this rises 

 the inner fringe, when that is present ; and it is it which con- 



7 



