1544. The component parts of the fungi are either perfectly indifferent, mucous or gelatinoid matter; or they are of an alcaline nature, being acrid, poisonous, and such like. Their odour is usually dead, disagreeable, and loathsome, or analogous to their essential process of decomposition. _CLASS II._ _Vessel-or Duct-plants--Mosses._ 1545. The intercellular passages or succigerent vessels of plants make their first appearance in a state of perfection, when, the cells being extended lengthways, have become hexagonal and are placed in regular juxtaposition. In these plants therefore we meet with regular cellular tissue, but still without spiral vessels or tracheæ. 1546. As the vessels or ducts constitute the fundamental tissue of the liber, while this is the principal system of the stalk; so now does the stem begin to be manifested and separated from the fruit. The seeds are no longer therefore distributed in the present class throughout the whole trunk, but developed in a special involucrum or theca, which corresponds to the puff-ball, or to the pileus of the higher organized fungi. 1547. Plants with vessels, and consequently a cauliform formation, have at once also the commencement of a bark, and next the green colour. The vascular are the first green plants, and differ chiefly through that character from the fungi. They are the _Fucacæ_ or _Sea-wracks_. 1548. They have the colour of the water, because the course of the sap corresponds to the aqueous process; they are aquatic, just as the brown fungi are terrestrial, plants. Their component parts are aqueous, indifferent, mucous, and filose. Their habitation is the water itself or bogs. If they occupy dry situations, they live only when it rains. 1549. They likewise pass through the five stages of vegetation, and form therefore five orders. 1550. Order 1. The lowest or _Tissue-mosses_, corresponding to the Uredines; are again naught but cells or mucous pellicles, but, from growing in water, and being consequently exposed to light and a stronger oxydation, they are green--_Tremellini_. 1551. They multiply by subdivision, since new vesicles or granules are developed in their interior, which become separated, and subsist or continue to grow for themselves. They therefore originate also by æquivocal generation, but by such an one as constantly occurs in water and light. 1552. The second order, or the _Vascular mosses_ corresponds to the sheaths, or to the Hyphomycetes. They are long filaments replete with granules, growing in water, and therefore green--_Confervaceæ_. These plants begin to ramify, and either increase by this means or by effusion of granular matter.