168 MORPHOLOGY. 



The rootless Agamce agree so far with the Gymnosporce, that they show- 

 no trace of a distribution of the fluid from a definite point through the 

 plant, or even appear to admit of the possibility of such a thing. Indeed 

 they do not need liquid water for the nutrition of all their separate parts, 

 yet they require an atmosphere saturated with vapour. A plant of 

 Polyfrichium, for instance, with its lower extremity in water, and its 

 surface protected from evaporation by oil, or exposed to a dry atmosphere 

 in a state of agitation, will fade as far down as it is out of the water, and 

 decay, but will vegetate vigorously again as soon as it is surrounded, by 

 means of a glass bell, with an atmosphere saturated with aqueous vapour. 



a. Rootless Agam&. 

 IV. LIVERWORTS (Musci HEPATICI). 



97. The developed plant, like the Mosses, has no proper root. 

 The stem manifests two main forms : first, the ordinary one, analo- 

 gous to the stem of the Mosses ; and secondly, another in which it 

 is expanded into flat and more riband-like form, instead of in a linear 

 direction. The former has always fronds (leaves), the latter, only the 

 rudiments of such, or none at all. The former is seldom upright, 

 but recumbent ; the latter (caulis frondosus) is either partially 

 developed in a filamentous form, and only flattened at the extre- 

 mity, or wholly and entirely flat ; in both cases it is differently 

 formed, but most frequently forked or digitate, and very rarely 

 pinnate. In a small number, for instance, Riccia fluitans, Antho- 

 ceros l&vis, &c., the whole plant consists only of tolerably uniform 

 flattened cells, ranged side by side, which can neither be considered 

 as stem or frond. Here the bifurcated division predominates very 

 considerably, and the manner in which the plants grow in all 

 directions from one point gives the Ricciecc in part a great resem- 

 blance to Lichens, Fronds (leaves) occur in all Liverworts, at 

 least as parts of the fructification, although in the case of the last- 

 mentioned this is somewhat doubtful. The forms of the leaves are 

 very various. With but few exceptions, the leaves are so directed 

 that they lie in one plane on either side of the stem ; on a flat stem 

 they are very stunted, and occur upon the lower surface only. The 

 leaves are occasionally cut into filiform segments, more rarely simple, 

 frequently multifariously lobed at the margin, either bifid or multi- 

 fid. In the bifid we often find a large and a smaller lobe (^auricula), 

 and the leaf folded together in the line of division between them. 

 The stem has frequently two kinds of leaves ; larger ones above, 

 which appear to be in two lines on a depressed surface, and smaller 

 ones varying in form, and which occur only upon the lower side of 

 the stem (amphigastria y stipules). In the axils of the leaves, buds are 

 developed, and from these ramifications which give not unfrequently 

 a pinnate appearance to the stem, owing to the leaves expanding 

 in one plane surface. Even in Liverworts, particular cells occa- 

 sionally emancipate themselves from the general combination of 

 individuality, and become developed into new plants; whilst in 



