"The number of living creatures, of all orders, whose existence intimately depends on the kelp, is wonderful. A large volume might be written, describing the inhabitants of one of these beds of sea-weed. Almost every leaf, except those that float on the surface, is so thickly incrusted with corallines as to be of a white colour. We find exquisitely delicate structures, some inhabited by simple hydra-like polypi, others by more organised kinds and beautiful compound ascidiæ. On the flat surfaces of the leaves, various patelliform shells, trochi, uncovered mollusks, and some bivalves are attached. Innumerable crustacea frequent every part of the plant. On shaking the great entangled roots, a pile of small fish, shells, cuttle-fish, crabs of all orders, sea-eggs, star-fish, beautiful holothuriæ (some taking the external form of the nudibranch mollusks), planariæ, and crawling nereidous animals of a multitude of forms, all fall out together. Often as I recurred to a branch of the kelp, I never failed to discover animals of new and curious structure. In Chiloe, where, as I have said, the kelp did not thrive very well, the numerous shells, corallines, and Crustacea were absent, but there yet remained a few of the Flustraceæ, and some compound ascidiæ; the latter, however, were of different species from those in Tierra del Fuego. We here see the fucus possessing a wider range than the animals which use it as an abode.
"I can only compare these great aquatic forests of the southern hemisphere with the terrestrial ones in the intertropical regions. Yet, if the latter should be destroyed in any country, I do not believe nearly so many species of animals would perish, as under similar circumstances would happen with the kelp. Amidst the leaves of this plant numerous species of fish live, which nowhere else would find food or shelter; with their destruction the many cormorants, divers, and other fishing-birds, the otters, seals, and porpoises, would soon perish also; and lastly the Fuegian savage, the miserable lord of this miserable land, would redouble his cannibal feast, decrease in numbers, and perhaps cease to exist."
For many a day's sail before reaching Cape Horn, large bundles of the macrocystis detached by the storm announce to the navigator that he is approaching the desolate coasts of Tierra del Fuego.
"We succeeded," says Professor Meyen, in his Reise um die Welt, "in getting hold of one of these floating islands, which, amid loud acclamations, was hauled upon deck by the exertions of five men. It was quite impossible to disentangle the enormous mass; we could only detach, to the length of about sixty feet, what we considered to be the chief stem; the branches were from thirty to forty feet long, and as thick as the principal trunk from which they sprang. We estimated the total length of the plant at about two hundred feet; the pear-shaped air vessels at the basis of the leaves were often six or seven inches long, and the leaves themselves measured seven or eight feet. On these swimming fucus-islands lived a vast multitude of various animals; thousands upon thousands of barnacles and sertulariæ, of crustaceans and annelides.
"The admiration which the gigantic sea-weeds of Tierra del Fuego excited in our minds equalled that which had been raised by the exuberant vegetation of the virgin forests of Brazil. One single plant of the Macrocystis pyrifera would suffice, like one of the mammoth-trees of those luxuriant woods, to cover a large space of land with its leaf-like substance. The quantity of small algæ, of sertularias, cellarias, and other minute animals dwelling on these swimming islands, surpasses in variety the multitude of parasitical plants bedecking the trees in a tropical forest. It seems as if, in these desolate and dreary regions, the generative powers of the planet were solely confined to the gigantic growth of submarine vegetation."
On the rocky coasts of the Falkland Islands are found no less astonishing masses of enormous sea-weeds, chiefly belonging to the genera Macrocystis, Lessonia, and Durvillea. Rent from the rocks to which they were attached, and cast ashore, they are rolled by the heavy surf into prodigious vegetable cables, much thicker than a man's body and several hundred feet long. Many of the rarest and most beautiful algæ may be here discovered, which have either been wrenched from inaccessible rocks far out at sea, along with the larger species, or have attached themselves parasitically to their stems and fronds. Many of them remind the botanist, by some similarity of form, of the sea-weeds of his distant home, while others tell him at once that he is far away in another hemisphere. The gigantic lessonias particularly abound about these islands. Their growth resembles that of a tree. The stem attains a height of from eight to ten feet, the thickness of a man's thigh, and terminates in a crown of leaves two or three feet long, and drooping like the branches of a weeping-willow. They form large submerged forests, and, like the thickets of the macrocystis, afford a refuge and a dwelling to countless sea animals.
A similar abundance of colossal algæ is found in the Northern Pacific, about the Kurile and Aleutic Islands, and along the deeply indented and channel-furrowed north-west coast of America.
Thus the Nereocystis lutkeana forms dense forests in Norfolk Bay and all about Sitcha. Its stem, resembling whipcord, and often above 300 feet long, terminates in a large air-vessel, six or seven feet long, and crowned with a bunch of dichotomous leaves, each thirty or forty feet in length. Dr. Mertens assures us that the sea-otter, when fishing, loves to rest upon the colossal air-vessels of this giant among the sea-weeds, while the long tenacious stems furnish the rude fishermen of the coast with excellent tackle. The growth of the nereocystis must be uncommonly rapid, as it is an annual plant, and consequently develops its whole gigantic proportions during the course of one brief summer.
Before proceeding to the third chief group of marine plants, the red sea-weeds, or Rhodosperms, I must mention the enormous fucus banks, or floating meadows of the Atlantic, which form undoubtedly one of the greatest wonders of the ocean.
We know that the mighty Gulf Stream, which rolls its indigo-blue floods from America to the opposite coasts of the Old World, flows partly southwards in the neighbourhood of Azores, and is ultimately driven back again to America. In the midst of these circuitous streams, from 22° to 36° N. lat., and from 35° to 65° W. long., extends a sea without any other currents than those resulting from the temporary action of the winds. This comparatively tranquil part of the ocean, the surface of which surpasses at least twenty times that of the British Isles, is found more or less densely covered with floating masses of Sargassum bacciferum. Often the sea-weed surrounds the ship sailing through these savannas of the sea, in such quantities as to retard its progress, and then again hours may pass when not a single fucus appears. While Columbus was boldly steering through the hitherto unknown fields of the Sargasso Sea, the fears of his timorous associates were increased by this singular phenomenon, as they believed they had now reached the bounds of the navigable ocean, and must inevitably strike against some hidden rock, if their commander persevered in his audacious course.