Next to the algæ in ascending order are those fantastic products of decay, the quick-growing, short-lived _Fungi_, animal-like in their mode of nutrition, plant-like in their fixity; then the _Lichens_, which, it is now generally agreed, are composite plants, being a special kind of parasite fungi growing on algæ. These are widely spread, living after the adaptive manner of simple forms, where nothing else can live, unwithered by the heat, unsmitten by the frost; redeeming the earth’s desolate places, from treeless desert flats far as the lines of enduring snow; spreading their flowerless patches of richest colors in metallic-like stain over rock and ruin; incrusting the trees with tint of freshness or touch of age, with hoary fringe or mock hieroglyph; and in their decay yielding rich soil wherein fern and flowering tree may strike root. In the _Mosses_, whose glossy, many-colored masses weave softest carpet over the earth, sharing in the service rendered by the humble lichens, the cells have become more developed into rudimentary root, stem, and leaf, manifesting still further transition toward unlikeness in parts due to division of function. But the structure is still cellular--_i. e._, there are no tissues and fibres. The mosses represent the intermediate form between the lowest and the highest cryptogams, between the green algæ--out of which the liverworts were probably developed--and the ferns, which arose out of liverworts. In the _Ferns_, the larger number of cells have joined together to form fibrous vessels, lengthening of thickening in varying shape and texture, according to the functions to be discharged by them, resulting in the woody tissue which enters into the structure of all the higher plants. The cells which are thus converted into tissue cease to grow; the formative protoplasm becomes the formed, having given up its life for the plant, and locked up in the compacted material a store of energy for service both within the plant and by the agency of the plant. The ferns and club-mosses and horsetails of the present day are the dwarfed representatives of the stately and luxuriant, although sombre, flowerless trees that composed the dense jungles of green vegetation in the _Devonian_ and succeeding _Primary_ periods. These are distinguished as the Era of Fern Forests, during which our fossil fuel was chiefly formed; and although the palm-like vegetation of the tropics more nearly approaches its _Devonian_ prototype, it falls far behind it in size and abundance. II. The _Phanerogams_ have their flowers with stamens and pistils conspicuous, and are divided, according to the formation of their seeds, into: 1. _Gymnosperms_, or naked-seeded, the ovules not being inclosed within a seed-vessel or ovary, but carried upon a cone, as in pines and allied species. 2. _Angiosperms_, or cover-seeded, the ovules being inclosed within an ovary.