NUTRITIVE ORGANS OF CELLULAR PLANTS. 309 



any observer, but some have thought that they have 

 perceived stomata in the capsule of Splaclmum. I have, 

 I confess, some doubt upoii this observation, which I 

 have not been able to verify ; but at least, it remains 

 certain that stomata are absent from all the nutritive 

 organs of Mosses. The stem, nerves, and the parts in 

 general, which in other plants present vessels only, here 

 offer bundles of elongated cellules, which replace the 

 vessels in appearance, and probably also in use. The 

 stem of Mosses is generally cylindrical ; and when it 

 appears compressed, as in Hypnum Schreheri, or tetra- 

 gonal, as in Bryum tetragonum, it is owing to the dispo- 

 sition of the leaves. The stems are sometimes very 

 long, as in Polytricha and Hypnum; sometimes very 

 short, as in several kinds of Weissia; sometimes so 

 short that they almost escape notice, and are only repre- 

 sented by a kind of little bulb, from which spring the 

 floral organs, as, for example, in several species of 

 Phascum, Buxhaumia, &c. These differences of size 

 are analogous to what we have above remarked, (Chap. I. 

 Sect. I.) on comparmg the stems of Draccena, for ex- 

 ample, with the bulbs of Liliaceae. 



The stem of Mosses is sometimes frequently simple, 

 as in JVebera pyriformis, and then the plant is almost 

 always annual. When it is branched, either by pro- 

 ducing young shoots at its base, or emitting lateral or 

 terminal branches, each of these shoots denotes generally 

 the growth of a year, and it is in this sense that Hedwig 

 has given them the name of Innovationes. But the 

 peculiar mode of growth of Mosses and of their ramifi- 

 cations has been but little studied. It appears that the 

 elongation of the stem or branch of a year is caused by 

 an extension which takes place principally at the upper 

 part, and which stops at a fixed period in each species, 

 nearly as in the branches of Dicotyledons : there must 



