xvi INTRODUCTION. 



mination of Mosses, from the Propagula" published in the 12th 

 Volume of the Acta Acad. Natures Curios, p. 169, has satisfac- 

 torily shown, that the lines of longitudinal cellules, of which the 

 stems and leaves are composed, are a continuation of the fibrous 

 radicles that constitute the roots. The greater are the number of 

 conferva-like shoots that unite, the thicker will be the stem, or the 

 broader will be the leaf which they compose. (See the excellent 

 plates accompanying Nees' Memoir just mentioned, t. 13, and 14.) 



Such being the case, it will naturally be expected that the 

 structure of the Mosses should be of the simplest kind. The 

 Phsenogamous plants, and even the Ferns are furnished with 

 tubular vessels. In the vegetables in question, no such tubular 

 vessels appear ; all their parts are composed of but one original 

 form, that is the cellular. A mass of cellules, more or less elon- 

 gated, constitutes the whole plant ; varying, however, infinitely in 

 size and shape. Sometimes they are roundish, or oblong, or 

 linear ; sometimes decidedly hexagonal. Even in the unripe 

 capsules and fruitstalks of these plants, the structure is as apparent 

 as in the stems and leaves. 



The want of tubular vessels is, however, compensated by the 

 softness, delicacy, and absorbent property of the cellular tissue ; 

 and, indeed, in no other plants are the elegant and beautiful 

 forms of that texture so distinctly displayed as in the Mosses ; 

 except, indeed, it be in the JungermannicB, which, in the formation 

 of their cellules, bear a close similarity with those I am now 

 describing. 



The roots of the Mosses, are universally composed of ex- 

 tremely minute, simple, or branching fibres, generally thickly 

 matted together. In the creeping plants, as in the Hypnum tribe, 

 they grow from various parts, on the under side, of nearly the 

 whole length of the stem. Even some that are of an upright 

 growth, have this character, as Bartramia arcuata; in the case 

 of this Moss, the plants become thickly matted together, from the 



