Ferns, the highest order of cryptogamous plants, forming a natural group distinguished for beauty and elegance, and much cultivated for ornament. Ferns are leafy plants producing a stem or rhizome, which creeps below or upon the surface of the earth, and sometimes rises to the height of 50 ft. as a tree trunk, crowned with terminal leaves or fronds. The rhizome is a fibrous woody cylinder, growing only at the end, and so of equal diameter throughout, giving out rootlets anywhere on its surface, and presenting on a cross section a hard fibrous rind composed of the angular bases of fallen fronds, enclosing a cellular tissue with a ring of woody plates, folded and curled, which are in fact the bases of the leaf stalks, and in the centre a cellular mass or highly developed pith. The stem is in fact a consolidated bundle of leaf stalks. The frond is circinate or coiled in vernation, and when unfolded is often of great size (25 ft. long). From this and the minute subdivision of the frond it has been considered rather a leaf-bearing branch than a proper leaf; but there are all gradations from an entire frond to one most minutely divided, and in the latter case the membranous portion proves on examination to be one, however deeply incised.

The petiole is never sheathing or articulated at the base, although in some tropical species the base is much enlarged and forms an elastic joint, quite edible. The size of the fronds varies from a diameter of less than a quarter of an inch to an expansion unequalled by any other vegetable except some seaweeds. In several cases buds spring out on the surface or edges of the frond, and thus multiply the species; this is the case in the walking fern, camptosorus, where the tip of the elongated hastate frond bends to the earth and takes root, giving rise to new plants. The veins of the pinnae or leaflets of the fronds are variously arranged, and usually so definitely in each genus as to be used in generic distinctions. The fructification of ferns is always on the lower face of the fronds, which sometimes under its influence are reduced to simple supports in the shape of a spike or panicle; it consists of sporangia or capsules, each containing many spores, and usually attached to the nerves or veins, but sometimes covering the whole surface.

These capsules are grouped in clusters of various forms called sori, and each cluster is often covered until ripe by a fold of the leaf membrane called an indusium.-The order of ferns is divided into suborders, most botanists recognizing as many as eight, founded upon the structure, manner of attachment, and mode of opening of the sporangia. By far the largest of these suborders is the polypodiaceae, or true ferns, which includes the great majority of those with which we are familiar in the wild state or in cultivation. In ferns of this suborder the structure of the sporangium is curious. A little bundle of cellular pores on a stem of the same cell formation is clasped around by a ring of thick and elastic segments, each resembling a U with the rounded part inward and the sides united. While the sporangium is alive and full of sap the arms of the remain almost parallel; but as the ring dries the arms shrink together, and the capsule is ruptured, often with force enough to throw the minute spores to some distance. The position of the sporangia on the frond is an important generic distinction.

In the common rock fern {polypodium) they are round, cinnamon-colored dots in rows each side of the midrib; in hart's tongue (scolopendrium) they form numerous obliquely transverse lines; in maidenhair (adiantum) a bit of the edge of the frond folds over the capsules; in the brake (pteris) the whole edge is folded over; and in the asplenium and many other ferns the sporangia are in oblong masses pinnately arranged each side of the midrib of the smaller divisions of the frond. In hymenophyllum, of a different suborder, the capsules are contained in a calyxlike urn springing from the terminal veins. In the ophioglossacece, which include our common adder's tongue and moon wort, the sporangia are entirely without the elastic ring, and open by a transverse slit into two valves. The spores are very minute and of various shapes, and form the brown (rarely green) dust which falls when a ripe frond is shaken. The mode in which ferns are fecundated is a modern discovery, but the process may be watched under the microscope by sowing the spores of any common fern in a moist place.

The spore swells with the moisture and ruptures its walls; a little radicle or rootlet is thrown out, consisting of a single cell, and at the same time another cell spreads out as a tube of irregular form, which soon forms partitions through its mass, and by multiplication of these cells becomes a small green leaflike expansion called a prothallus. On the under surface of this spring organs of two kinds, the antheridia and archegonia. The former are tilled with minute spiral bodies called an-therozoids, which have cilia and the power of motion in water, which is always abundant on the under side of the prothallus; when mature they pass into the archegonia, which are cup-like organs, open when mature, and containing one or more cells which the contact of the antherozoids causes to develop, and soon a root appears, then the first frond, and so on until the complete fern is the result.-The species of ferns at present described are 2,235, although some botanists make the number above 3,000. In the earlier geological ages ferns formed a most important part of the vegetation, as is plainly seen in the coal fields, where numerous fronds and stems are preserved; but from the general absence of fructification on these remains, it is often impossible to distinguish the species.

They are now found all over the world, but especially in the warmer and moister climates; thus in the Antilles they comprise 1/10 of the vegetation, in Oceanica 1/4 or 1/5, in St. Helena 1/8, in Juan Fernandez 1/2, and in England 1/35. The Hawaiian islands and New Caledonia are particularly rich in species. The tree ferns are chiefly confined to the torrid zone, but Martens found them 50 ft. high in Japan, and Robert Brown found arborescent ferns at the extremity of Tasmania, and even at Dusky bay in New Zealand, near lat. 460 S. Most tree ferns are easily propagated by planting sections of their stems, which readily leaf out.-For the classification of ferns, which is very unsettled and depends on technical differences, see Hookers Genera," Hooker and Baker's "Synopsis," or Smith's"Ferns, British and Foreign;" and for local descriptions see local floras.-The uses of ferns are not very prominent. On the Hawaiian islands the stem of a tree fern is often baked in the steam cracks of the volcanoes, and by long cooking becomes quite palatable, although rather leathery, and tasteless without salt. The enlarged bases of the petioles of other species are cooked and eaten in times of scarcity: when raw they smell precisely like a raw potato.

The stems and midribs of some smaller species are woven into baskets and hats. A few species are considered medicinal, and some are aromatic and used to scent cocoanut oil.-In cultivation ferns may be adapted to a variety of localities; for, although generally found in shady places, many thrive in the full tropical sun if the air be moist, and some grow on dry rocks and even on the uninviting surface of lava streams. A compost of peat or bog earth, decayed leaf mould, yellow loam, and silver sand in equal proportions, may be used in potting ferns; but it must be well underdrained, and the addition of a few fragments of mortar or limestone is advantageous. Several species climb on rocks, like ivies; others cling to trees, or, like the beautiful climbing fern lygo-dium), run over bushes. About 1830 Mr. N. B. Ward of England, in investigating the transformations of an insect, buried its chrysalis in some earth in a closed glass bottle. A seedling fern and a grass sprang up from the soil and grew within the confined atmosphere of the vessel. This led to experiments upon the growth of plants, especially ferns, in close cases, and resulted in establishing the fact that these plants would not only grow under such conditions, but that most terns would flourish much better than in the open air.

Wardian cases, which resulted from this discovery, are now in general use for the cultivation of ferns, and are among the most popular as they are the most beautiful of household ornaments.

Rock Fern (Polypodium vulgare).

Rock Fern (Polypodium vulgare).

Hart's Tongue (Scolopendrium officinarum).

Hart's Tongue (Scolopendrium officinarum).

Maiden hair (Adiantum pedatum).

Maiden-hair (Adiantum pedatum).

Common Brake (Ptoris aquilina).

Common Brake (Ptoris aquilina).

Adder's Tongue (Ophio glossuin vulgatum).

Adder's Tongue (Ophio-glossuin vulgatum).

Tree Ferns.

Tree Ferns.

1. Alsophila excelsa. 2. Dicksonia arborescens. 3. Cyathea elegrans. 4. Cyathea arborea. 5. Hemitelia speciosa. 6. Drynaria coronans. 7. Platycerium grande. 8. Bird's nest fern. 9. Asplenium lucidum.