minute varieties of tint and form contributed by the lower orders of vegetation-the starry flower, the plumy fern, or the umbrella-like fungus upon the ground, and the clustered moss and trailing lichen upon the tree; and yet it is with these small and apparently insignificant objects that nature shades the picture, balances and contrasts the colouring, clothes the nakedness, and softens down the irregularities and deformities of the whole scene, which would otherwise be stiff and hard as a forest-piece painted by a Chinese artist.

Lichens are exceedingly diversified in their form, appearance, and texture. Upwards of four hundred and fifty different kinds have been found in Great Britain alone, while altogether between two and three thousand species have been discovered in different parts of the world by the zealous researches of naturalists. In their very simplest rudimentary forms, they consist apparently of nothing more than a collection of powdery granules, so minute that the figure of each is scarcely distinguishable, and so dry and utterly destitute of organization that it is difficult to believe that any vitality exists in them. Some of these form ink-like stains on the smooth tops of posts and felled trees; others are sprinkled like flower of brimstone or whiting over shady rocks and withered tufts of moss; while a third species is familiar to every one, as covering with a bright green incrustation the trunks and boughs of trees in the squares and suburbs of smoky towns, where the air is so impure as to forbid the growth of all other vegetation. It also creeps over the grotesque figures and elaborate carving on the roofs and pillars of Roslin Chapel, near Edinburgh, and

E

gives to the whole an exquisitely beautiful and romantic appearance. One species, the Lepraria Jolithus, is associated with many a superstitious legend. Linnæus, in his journal of a tour through Eland and East Gothland, thus alludes to it :-" Everywhere near the road I saw stones covered with a blood-red pigment, which on being rubbed turned into a light yellow, and diffused a smell of violets, whence they have obtained the name of violet stones; though, indeed, the stone itself has no smell at all, but only the moss with which it is dyed." At Holywell, in North Wales, the stones are covered with this curious lichen, which gives them the appearance of being stained with blood; and of course the peasantry in the neighbourhood allege, that it is the ineffaceable blood which dropped from St. Winnifred's head, when she suffered martyrdom on that sacred spot. A higher order of lichens (Boomyces) is furnished, besides this powdery crust, with solid, fleshy, club-shaped fructification; while a singularly beautiful genus (Calicium), usually of a very vivid yellow colour, spreading in indefinite patches over oaks and firs, is provided with capsules somewhat like those of the mosses. These capsules, though thickly scattered over the crust, are so minute as to be scarcely distinguishable by the naked eye, but under the microscope they present a truly lovely appearance. They are cup or urn-shaped, of a coal-black colour, and supported by a slender stalk about the thickness of a horse-hair. At an early stage they are covered with a very delicate veil, which stretches completely over their mouth; but this soon vanishes, and exposes to view a mass of black or brown seeds, like the ovule in an acorn,

which the slightest touch of the tiniest insect's wing can dislodge, and send away on the breeze in search of a habitat for another colony.

Most of the crustaceous lichens are merely grey filmy patches inseparable from their growing places, indefinitely spreading, or bounded by a narrow line-like border, which always intervenes to separate them when two species closely approximate, and studded all over with black, brown, or red tubercles. The foliaceous species, again, are usually round rosettes of various colours, attached by dense black fibres all over their under-surface, or by a single knot-like root in the centre. Some are dry and membranaceous; while others are gelatinous and pulpy, like aërial sea-weeds left exposed on inland rocks by the retiring waves of an extinct ocean. Some are lobed with woolly veins underneath; and others reticulated above, and furnished with little cavities or holes on the undersurface. The higher orders of lichens, though destitute of anything resembling vascular tissue, exhibit considerable complexity of structure. Some are shrubby, and tufted, with stem and branches, like miniature trees; others bear a strong resemblance to the corallines of our sea-shores; while a third class, "the green-fringed cupmoss with the scarlet tip," as Crabbe calls it, is exceedingly graceful, growing in clusters beside the black peatmoss or under the heather tuft,

"And, Hebe-like, upholding

Its cups with dewy offerings to the sun."

As an illustration of the extraordinary appearances which lichens occasionally present, I may describe the Opegrapha or written lichen (Fig. 7), perhaps the most

curious and remarkable member of this strange tribe. In her cactuses1 and orchids sportive nature often displays a ludicrous resemblance to insects, birds, animals, and even the "human face and form divine;" but this is one of the few instances in which she has condescended to imitate in her vegetable productions the written language of man. The crust of this curious autograph of nature is a mere white tartareous film of indefinite extent,

FIG. 7.-OPEGRAPHA SCRIPTA.

sometimes bounded by a faint line of black like a mourning letter. It spreads over the smooth bark of trees, particularly the beech, the hazel, and the oak. On the birch-tree—whose smooth, snow-white, vellum-like bark seems designed by nature for the inscription of lovers' names and magic incantations-it may often be seen covering the whole trunk. The fructification consists of long wavy black lines, sometimes parallel like Runic inscriptions; sometimes arrow-headed, like the cuneiform characters engraved upon the monumental stones of Persepolis and Assyria; and sometimes gathered together

1 As, for instance, Cactus senilis.

in groups and clusters, bearing a strong resemblance to Arabic and Chinese letters.

In that well-known and interesting work, "Travels in Tartary, Thibet, and China," by the French Lazarists Huc and Gabet, there is a long description of a very remarkable phenomenon called the "Tree of Ten Thousand Images," found by them near the town of Koumboum in Thibet. For the sake of those who may not have access to the original work, I shall quote the description entire. "At the foot of the mountain on which the Lamasery stands, and not far from the principal Buddhist temple, is a great square enclosure, formed by brick walls. Upon entering this, we were able to examine at leisure this marvellous tree, some of the branches of which had already manifested themselves above the wall. Our eyes were first directed with earnest curiosity to the leaves, and we were filled with an absolute consternation of astonishment at finding that in point of fact, there were upon each of the leaves well formed Thibetian characters, all of a green colour, some darker, some lighter than the tree itself. pression was a suspicion of fraud on the Lamas; but after a minute examination of we could not discover the least deception. The characters all appeared to us portions of the leaf itself, equally with its veins and nerves; the position was not the same in all; in one leaf they would be at the top, in another in the middle, in a third at the base or at the side; the younger leaves represented the characters only in a partial state of formation. The bark of the tree, and its branches-which resemble that of the plane-tree-are

Our first im

part of the

every detail,