BOOK I. STRUCTURE OF IMPERFECT PLANTS. 141 



botany, who is attracted perhaps only by what is specious in the plant or flower, but who, 

 when the desire of botanical knowledge shall have inspired him with a relish for micro- 

 scopical observation, will find the study of the mosses to be no less interesting than that 

 of the more perfect plants, and the form and texture of their parts to be no less beautiful 

 and elegant than that of the most gaudy flowers. (Jig. 44.) 



SUBSECT. 3. Hepaticee. 



599. The hepatlcte are a tribe of small and herbaceous plants resembling the mosses, but 

 chiefly constituting fronds, and producing their fruit in a capsule that splits into longi- 

 tudinal valves. The name is derived from a Greek word signifying the liver, because 

 perhaps some of them were formerly employed as a remedy in diseases of the liver ; or 

 because some of them exhibit, in their general aspect, a slight resemblance to the lobes 

 of the liver. In their habitations, they affect for the most part the same sort of situations 

 as the mosses, being found chiefly in wet and shady spots, by the sides of springs and 

 ditches, or on the shelving brinks of rivulets, or on the trunks of trees. Like the mosses, 

 they thrive best also in cold and damp weather, and recover their verdure, though dried, 

 if moistened again with water. The hepaticae and the mosses are indeed so nearly al- 

 lied, that they have generally been regarded as constituting but one family, and classed 

 together accordingly ; the latter under the title of musci frondosi, and the former under 

 that of musci hepatici. Such was the division even of Hedwig ; but later botanists have 

 found it to be more consonant to the principles of sound and scientific arrangement, 

 to separate the hepaticae from the mosses altogether, and to convert them into a distinct 

 tribe. 



SUBSECT. 4. Algce and Lichencz. 



GOO. The term algce, or sea-weeds, among modern botanists, includes not merely marine 

 and many other immersed plants, but also a great variety of plants that are not even 

 aquatics. All the algae, or, according to the Jussieuean terminology, algeae, however, 

 agree in the common character of having their herbage frondose, or but rarely admitting 

 of the distinction of root, stem, and leaf, and their fructification imbedded either in the 

 substance of the frond itself, or in some peculiar and generally sessile receptacle. The 

 algeae were formerly divided into the six following genera, lichen, tremella, fucus, ulva, 

 conferva, byssus ; but now the genus lichen forms an order of itself. 



601. The utility of the algae is obviously very considerable, whether we regard them as 

 furnishing an article of animal food, or as applicable to medicine and the arts. The 

 fucus edulis, and several other fuci, are eaten and much relished by many people, whether 

 raw or dressed, and it is likely that some of them are fed upon by various species of fish. 

 The fucus lichenoides {Turner, c. 118.) is now believed to be the chief material of the 

 edible nests of the East India swallows, which are so much esteemed for soups, that they 

 sell in China for their weight in gold. When disengaged from their placaof growth and 

 thrown upon the sea-shore, the European algae are often collected by the farmer and used 

 as manure. They are often also employed in the preparation of dyes, as well as in the 

 lucrative manufacture of kelp, a commodity of the most indispensable utility in the im- 

 portant arts of making soap and glass. . 



602. The utility of the lichena is also worthy 

 of. notice. The lichen rangiferinus (Jig. 45.) 

 forms the principal nourishment of the rein-deer 

 during the cold months of winter, when all other 

 herbage fails. The lichen islandicus is eaten 

 by the Icelanders instead of bread, or used in 

 the preparation of broths, and like the lichen 

 pulmonarius, has been lately found to be bene- 

 ficial in consumptive affections. Many of them 

 are also employed in the preparation of some of 

 our finest dyes, or pigments ; and it is from the 

 lichen parellus that the chemical analysist ob- 

 tains his litmus. The lichens and the mosses 

 seem instituted by nature to provide for the uni- 

 versal diffusion of vegetable life over the whole 

 surface of the terrestrial globe. The powdery 

 and tuberculous lichens attach themselves even 

 to the bare and solid rock. Having reached 



the maturity of their species, they die and are converted into a fine earth, which forms a 

 soil for the leathery lichens. These again decay and moulder into dust in their turn ; 

 and the depth of soil, which is thus augmented, is now capable of nourishing and support- 

 ing other tribes of vegetables. The seeds of the mosses lodge in it, and spring up into 



