Page:The Botany of the Antarctic Voyage.djvu/494

458 with a very thin cuticular layer of the frond. The presence of this cuticle is owing to the peculiar manner in which the superficial or sporiferous cells of the frond dehisce transversely, allowing the dispersion of the spores (shown in the dissection of Macrocyst'is, given at Plate CLXIX., CLXX. Fig. 2).

This and the following are truly wonderful Alga, whether seen in the water or on the beach ; for they are arborescent, dichotomously branched trees, with the branches pendulous and again divided into sprays, from which hang linear leaves 1-3 feet long. The trunks usually are about 5-10 feet long, as thick as the human thigh, rather contracted at the very base, and again diminishing upwards. The individual plants are attached in groups or solitary, but gregarious, like the pine or oak, extending over a considerable surface, so as to form a miniature forest, which is entirely submerged during high-water or even half-tide, but whose topmost branches project above the surface at the ebb. To sail in a boat over these groves on a calm day affords the naturalist a delightful recreation; for he may there witness, in the Antarctic regions, and below the surface of the ocean, as busy a scene as is presented by the coral reefs of the tropics. The leaves of the Lessonia are crowded with Sertulariee and Mollusca, or encrusted with Flustra ; on the trunks parasitic Alga abound, together with Chitons, Patella, and other shells ; at the bases, and amongst the tangled roots swarm thousands of Crustacea and Radiata, whilst fish of several species dart amongst the leaves and branches. But it is on the sunken rocks of the outer coasts that this genus chiefly prevails, and from thence thousands of these trees are flung ashore by the waves, and with the Macrocystis, and D'Urvillea, form along the beach continued masses of vegetable rejectamenta, miles in extent, some yards broad, and three feet in depth; the upper edge of this belt of putrefying matter is well in-shore, whilst the outer or seaward edge dips into the water, and receives the accumulating wreck from the sub-marine forests throughout its whole length. Amongst these masses the best Alga of the Falklands are found, though if the weather be mild, the stench, which resembles putrid cabbage, is so strong as to be almost insufferable. The ignorant observer at once takes the trunks of Lessonia thus washed up for pieces of drift-wood, and on one occasion, no persuasion could prevent the captain of a brig from employing his boat and boat's crew, during two bitterly cold days, in collecting this incombustible weed for fuel!

The trunks, which contract to one-fourth of their original dimensions when dry, and become deeply furrowed, are perfectly smooth and cartilaginous when fresh. On being cut across, the curious appearance of concentric elliptical rings, in many respects similar to, though very different from, those of an Exogenous trunk, is very evident. These rings surround a lance-shaped pale line, which occupies the broad axis of the compressed stem, without reaching across it, and appears to afford some rude indication of the age of the plant, though of this we could by no means satisfy ourselves. It is singular that this, the most arborescent of the Alga, and the beautiful Usnea melaxantlia, the most tree-like in form of the Lichens, are nearly the only plants of the Orders to which they respectively belong, conspicuously presenting even a semblance, if it be no more, to a growth that indicates an increase by periodical accessions to the circumference.

The substance of the trunk of the Lessonia is very usefully employed by the Gauchoes, for knife-handles ; the haft of the instrument is plunged into a rudely-shaped piece of this weed, which contracts into a substance harder than horn. The range of the present species is from the Falkland Islands to Cape Horn, and thence north along the coasts of South America probably to Valparaiso.

Plate CLXVII. — CLXYIII. A. — apex of a branch and fronds, of the natural size ; A. 1, portion of stem showing layers of cellular tissue and air-cell : — magnified.

2. Lessonia nigrescens, Bory, in Dwperrey Yoy.Bot. Crypt, p. 80. t. 5. Post, et Ruppr. Illust. Alg. pp. 2 et 4. t. 4 et 39. f. 11 et 13. (Tab. CLXVII.— CLXVIII. C.)

Hab. Hermite Island, Cape Horn, and the Falkland Islands; very abundant, with the former species.

A species very similar to the preceding in general appearance, but of a different consistence and colour.