176 



MORPHOLOGY. 



131 



to the stem. On isolating a 

 young plant of Funaria hygrome 

 trica (fig. 131.), it will appear 

 to be merged below into the Con- 

 ferva-like cells of the proem- 

 bryo (b, b\ or rather grown into 

 it, and only separated with mor- 

 phological distinctness in an up- 

 ward direction (a). This justi- 

 fies the definition of frondose 

 Mosses as rootless Agamce. My 

 investigations into the develop- 

 ment of the leaf, which are un- 

 fortunately still very imperfect, 

 show with certainty, at least in 

 Sphagnum, that the leaf as in the 

 Phanerogamia is protruded from 

 the axis, and that, consequently, 

 the idea of a leaf and stem, as I 

 define them, may be fully applied 

 to Mosses. The stalks often 

 range themselves irregularly, especially in the upright stem (here they 

 are sometimes pyramidal), but likewise in the recumbent and floating 

 stem ; they are more rarely (apparently) pinnate (as, for instance, even in 

 Hypnum molluscum and Crista castrensis &c.) in most stems pressed to 

 the ground. The condition of the highly hygroscopic leaves, when per- 

 fectly dry, is also peculiar and important with respect to the determina- 

 tion of species, as they curl up in a very definite and diversified manner (as, 

 for instance, in Orthotrichum crispum). In Mosses growing in the water, 

 the central nerve remains frequently upon the stem, as a little point 

 (caulis spinulosus, in 

 Fontinalis) after the 

 destruction of the sub- 

 stance of the lamina. In 

 some Mosses small la- 

 mellae are found, placed 

 lengthwise, either upon 

 the central nerves (Ca- 

 tharinea) (fig. 132.), 

 ( Schistidium), or upon 

 the whole surface of 

 the leaf (Polytrichum). 

 We but rarely find 

 different leaves upon the same Moss, as in Sphagnum. Here the lateral 

 stalks are collected in little bundles, two generally hanging down, while the 

 others stand straight out : these latter have always differently formed, nar- 

 rower leaves than the former, and both generally deviate regularly in their 

 form from the stem leaves. Occasionally the leaves first originating in ger- 

 mination differ from those subsequently formed upon the full-grown plant 



131 Funaria hygrometrica. The little plant (a) has arisen in such a manner from the 

 filaments of the proembryo (6 6), that no distinctly marked radical extremity is to be 

 defined below, the plant passing gradually into the filiform cells of the proembryo. 



132 Section through middle of leaf of Catharinea undulata. Upon the central nerves 

 (c) are lamellae, placed lengthwise (a) ; at b, leaf-cells. The central nerve consists 

 of much thickened, liber-like cells, and other larger thinner- walled cells enclosed by it. 



132 



