LIVERWORTS 107 



The frond-like form of liverwort, on the other 

 hand, cannot possibly be mistaken for a moss, 

 though plants of this class are sometimes very 

 like certain of the lichens in outward appear- 

 ance, and are still more liable to be confused with 

 the early stage, or prothallium, of a fern, to which 

 some of them bear a very strong resemblance. In 

 this group the whole plant takes the form of a flat 

 green plate or frond, which grows quite close to 

 the surface of the soil or other substance to which 

 it happens to be attached. Plate VIII. figs. 1 to 

 16 are all illustrations of leafy liverworts, while 

 figs. 17 to 20 represent frond-like plants. But 

 here we are reminded again of the constantly 

 recurring fact that Nature seldom draws a hard- 

 and-fast line ; for while in some instances there 

 is no difficulty in saying at sight whether any 

 particular plant belongs to one group or to the 

 other, yet there are a few that are evidently on 

 the border line, and that clearly show how the 

 two forms merge the one into the other. 



Habitats. From what has already been said, it 

 will have been inferred that both mosses and 

 liverworts live in very similar homes, and under 

 much the same conditions. The latter, however, 

 are by no means so cosmopolitan as their relatives, 

 and are certainly much more shy of contamination 

 with smoke ; hence it is that if we would make 

 their close acquaintance it becomes necessary 

 to seek them out in localities which are specially 



