The peculiar colouring of the Red Sea, from which it has derived its name, is owing to the presence of a microscopic alga, sui generis, floating at the surface of the sea and even less remarkable for its beautiful red colour than for its prodigious fecundity.
I could add many more examples, where, either from minute algæ or from small animals, the deep blue sea suddenly appeared in stripes of white, yellow, green, brown, orange or red. For fear, however, of tiring the reader's patience, I shall merely mention the olive-green water, which covers a considerable part of the Greenland seas. It is found between 74° and 80° N. lat., but its position varies with the currents, often forming isolated stripes, and sometimes spreading over two or three degrees of latitude. Small yellowish Medusæ, of from one-thirtieth to one-twentieth of an inch in diameter are the principal agents that change the pure ultramarine of the Arctic Ocean into a muddy green. According to Scoresby, they are about one-fourth of an inch asunder, and in this proportion a cubic inch of water must contain 64, a cubic foot 110,592, a cubic fathom 23,887,872, and a cubic mile nearly twenty-four thousand billions! From soundings made in the situation where these animals were found, the sea is probably more than a mile deep; but whether these substances occupy the whole depth is uncertain. Provided, however, the depth to which they extend be about 250 fathoms, the immense number of one species mentioned above may occur in a space of two miles square; and what a stupendous idea must we form of the infinitude of marine life, when we consider that those vast numbers, beyond all human conception, occupy after all only a small part of the green-coloured ocean which extends over twenty or thirty thousand square miles! It is here that the giant whale of the north finds his richest pasture-grounds, which at the same time invite man to follow on his track. A small red crustacean (Cetochilus australis) which forms very extensive banks in the Pacific, and in the middle of the Atlantic about 40° S. lat., affords a similar supply of food to the whales frequenting those seas, and exposes them to the same dangers.
When the sea is perfectly clear and transparent, it allows the eye to distinguish objects at a very great depth. Near Mindora, in the Indian Ocean, the spotted corals are plainly visible under twenty-five fathoms of water. The crystalline clearness of the Caribbean sea excited the admiration of Columbus, who in the pursuit of his great discoveries ever retained an open eye for the beauties of nature. "In passing over these splendidly adorned grounds," says Schöpf, "where marine life shows itself in an endless variety of forms, the boat, suspended over the purest crystal, seems to float in the air, so that a person unaccustomed to the scene easily becomes giddy. On the clear sandy bottom appear thousands of sea-stars, sea-urchins, molluscs, and fishes of a brilliancy of colour unknown in our temperate seas. Fiery red, intense blue, lively green, and golden yellow perpetually vary; the spectator floats over groves of sea-plants, gorgonias, corals, alcyoniums, flabellums, and sponges, that afford no less delight to the eye, and are no less gently agitated by the heaving waters, than the most beautiful garden on earth when a gentle breeze passes through the waving boughs."
With equal enthusiasm De Quatrefages expatiates on the beauties of the submarine landscapes on the coast of Sicily. "The surface of the waters, smooth and even like a mirror, enabled the eye to penetrate to an incredible depth, and to recognise the smallest objects. Deceived by this wonderful transparency, it often occurred during my first excursions, that I wished to seize some annelide or medusa, which seemed to swim but a few inches from the surface. Then the boatman smiled, took a net fastened to a long pole, and, to my great astonishment, plunged it deep into the water before it could attain the object which I had supposed to be within my reach. The admirable clearness of the waters produced another deception of a most agreeable kind. Leaning over the boat, we glided over plains, dales, and hillocks, which, in some places naked and in others carpeted with green or with brownish shrubbery, reminded us of the prospects of the land. Our eye distinguished the smallest inequalities of the piled-up rocks, plunged more than a hundred feet deep into their cavernous hollows, and everywhere the undulations of the sand, the abrupt edges of the stone-blocks, and the tufts of algæ were so sharply defined, that the wonderful illusion made us forget the reality of the scene. Between us and those lovely pictures we saw no more the intervening waters that enveloped them as in an atmosphere and carried our boat upon their bosom. It was as if we were hanging in a vacant space, or looking down like birds hovering in the air upon a charming prospect. Strangely formed animals peopled these submarine regions, and lent them a peculiar character. Fishes, sometimes isolated like the sparrows of our groves, or uniting in flocks like our pigeons or swallows, roamed among the crags, wandered through the thickets of the sea-plants, and shot away like arrows as our boat passed over them. Caryophyllias, Gorgonias, and a thousand other zoophytes unfolded their sensitive petals, and could hardly be distinguished from the real plants with whose fronds their branches intertwined. Enormous dark blue Holothurias crept along upon the sandy bottom, or slowly climbed the rocks, on which crimson sea-stars spread out immoveably their long radiating arms. Molluscs dragged themselves lazily along, while crabs, resembling huge spiders, ran against them in their oblique and rapid progress, or attacked them with their formidable claws. Other crustaceans, analogous to our lobsters or shrimps, gambolled among the fuci, sought for a moment the surface waters to enjoy the light of heaven, and then by one mighty stroke of their muscular tail, instantly disappeared again in the obscure recesses of the deep. Among these animals whose shapes reminded us of familiar forms appeared other species, belonging to types unknown in our colder latitudes: Salpæ, strange molluscs of glassy transparency, that, linked together, form swimming chains; great Beroës, similar to living enamel; Diphyæ hardly to be distinguished from the pure element in which they move, and finally, Stephanomiæ, animated garlands woven of crystal and flowers, and which, still more delicate than the latter, disappear as they wither, and do not even leave a cloud behind them in the vase, which a few moments before their glassy bodies had nearly entirely filled."
Hill at the Rapid on Bear Lake River. (North-West Territory, North America.)
[CHAP. II.]
THE WAVES OF THE OCEAN.