Chapter XL: Part II: The Inhabitants of the Sea (13)

In the British seas _four_ distinct and well-marked zones of life succeed each other in vertical extension. The first of these is the _littoral zone_, equivalent to the tract between tide-marks, but quite as manifest in those portions of the coast-line where the tides have a fall of only a foot or two, or even less, as in districts where the fall is very great. This important belt, which again forms four subdivisions, and is inhabited by animals and plants capable of enduring periodical exposure to the air, to the glare of light, the heat of the sun, the pelting of rain, and often to being more or less flooded with fresh water when the tide has receded, claims many genera as well as species peculiar to itself. "The verge of continual air is generally distinguished by the abundant presence of _Fucus canaliculatus_, among whose roots may be found crowds of small varieties of the periwinkle, called _Littorina rudis_, which indeed range out of the water considerably, and may be found adhering to rocks many feet above high-water mark." The second sub-region is marked by the abundance of a small dark rigid sea-weed, called _Lichina_, painting the rock sides as if with a dingy stripe. With it we find the larger forms of _Littorina rudis_, abundance of the common limpet (_Patella vulgata_), the common mussel (_Mytilus edulis_), and myriads of small seaside barnacles, often striping the sea-wall in a broad white band. "Where the shore shelves a little, and rocky ledges decline gradually into the sea, the common mussel delights to live, firmly anchored by its byssal cable in the crevices of rocks or among masses of gravel, the pebbles of which are tied together by its silky filaments." The rock sides and the floors of transparent pools are here often thickly coated with a nullipore, forming a hard pale red crust. The region of half-tide forms a third subdivision of the littoral zone, and is exceedingly prolific in marine animals and plants. "Here we find _Fucus articulatus_, with its graceful even-edged rich brown fronds, mingled occasionally with the less elegant _Fucus nodosus_. Here limpets throng, and dog-periwinkles (_Purpura lapillus_) crawl observantly, seeking to bore more passive mollusks and extract their juicy substance. This is the home of the best of periwinkles, the large black _Littorina littorea_, gathered in thousands for the London market. On our western coasts we find it in company with the purple-striped top-shell (_Trochus umbilicatus_), and towards the south with the larger _Trochus crassus_. Here also sea-anemones love to expand their many-armed disks, often glowing with the most brilliant colours." A fourth sub-region succeeds, the lowest belt above low-water mark, and is distinguished by the presence of the black saw-toothed sea-weed (_Fucus serratus_), so much used in the packing of lobsters for market. On its fronds creeps the lowest in grade of the periwinkles, the variously tinted _Littorina neritoides_, exhibiting every colour in its obtuse and thickened shell.

"At the verge of low-water mark, immediately below it, wherever the coast is rocky, there are all round the British shores, within a space of a few inches, a remarkable series of more or less distinctly defined belts, each consisting of a different species of sea-weed. These in succession are, the _Laurencia pinnatifida_ uppermost; then the green _Conferva rupestris_; then the elegant and firm, often iridescent, fronds of _Chondrus crispus_; and, lowermost, the thong-weed or _Himanthalia lorea_."

Succeeding the shore-band, or littoral zone, we have the _region of the great laminaria or tangle forests_, or in sandy places the waving meadows of zostera, or grass-wrack. It extends from the edge of low water to a depth varying in different localities, but seldom exceeding fifteen fathoms, and is itself divided into sub-regions, marked by belts of differently tinted algæ. This zone above all others swarms with life, and is the chief residence of fishes, mollusks, crustaceans, and invertebrata of all classes, remarkable for brightness and variety of colouring. "Here," says Mr. Godwin Austen, "is the chosen haunt of the nudibranchiate mollusks, animals of exceedingly delicate texture, extraordinary shapes, elegance of organs, and vividness of painting. Their bodies exhibit hues of a brilliancy and intensity such as can match the most gorgeous setting of a painter's palette. Vermilion red, intense crimson, pale rose, golden yellow, luscious orange, rich purple, the deepest and the brightest blues, even vivid greens and densest blacks, are common tints, separate or combined, disposed in infinite varieties of elegant patterns, in this singular tribe. Our handsomest fishes are congregated here, the wrasses especially, some of which are truly gorgeous in their painting. Here are gobies and more curious blennies, swimming playfully among these submarine groves. Strange worms crawl serpent-like about their roots, and formidable crustacea are the wild beasts who prowl amid their intricacies. The old stalks, and the surfaces of the rocky or stony ground on which they usually grow, are incrusted like the trunks of ancient trees or faces of barren rocks with lichenous investments. But whereas in the air these living crusts are chiefly if not all of vegetable origin, in the sea they are more often constructed out of animal organisms. Some of them are sponges, others are true zoophytes, others polyzoa or bryozoa, beings that have proved to belong to the class of mollusks, however unlike they may seem to shell-fish.

"In the middle and lower part of the Laminarian region around our shores the tangles become less plentiful as we descend, and at last become exceptional and disappear. But other sea-weeds are very abundant, especially those that delight in red or purple hues. Tender sea-mosses, exquisitely delicate in form and colouring, abound. Where none of these are very plentiful, we often find the coral-weed or nullipore in vast quantities, and assuming many strange modifications of form. Among these vegetable corals numbers of shells and articulate animals delight to live, and probably not a few feed upon their stony fronds. The Lima, a shell-fish related to the scallop, gathers the broken branches by means of prehensile tentacles, and constructs for itself a comfortable nest lined with a woven cloth of byssal threads. Numerous fishes resort to these rugged pastures in order to deposit their spawn among the gnarled branchlets."

To the laminarian succeeds the _coralline zone_, extending in most places some thirty fathoms or more. Plants, indeed, are rare, but here the horny plant-like sertularias love to rear their graceful feathery branches, and form miniature gardens of fairy-like delicacy and beauty; and here carnivorous mollusks, whelks above all, prowl in great numbers. Bivalves of remarkable elegance, especially clams and scallops, are found buried in multitudes beneath its gravels and muddy sands; and no less plentifully congregate the spider-crabs, with many other peculiar crustaceans. As a natural consequence of this well-furnished table, fishes abound, and many of our deep sea and white fisheries owe their value to the zoological features of the coralline zone.

Last and lowest of our regions of submarine existence is that of _deep-sea corals_, so named on account of the great stony zoophytes characteristic of it in the oceanic seas of Europe. Many sea-stars and sea-urchins are likewise found in this region, in the depths of which the number of peculiar creatures is few, yet sufficient to give it a marked character.

The aspect of the British submarine fauna is in general more remarkable for elegance of form and neat simplicity than for glaring or vivid hues. "The smaller kinds of sponges are not seldom brilliantly dyed, but the more conspicuous kinds are tawny or brownish. The sea-anemones are elegantly variegated with rich colours, but the majority of zoophytes are not strikingly tinted. The star-fishes, as a group, are most remarkable among the invertebrata for gorgeous painting, but our sea-urchins are sombre when compared with their relatives from warmer seas. The jelly-fish are occasionally tinged with delicate hues, and some of the smaller kinds even showily ornamented; but those which most figure in our waters are not conspicuous on account of colour, however elegant in their contours. Our marine shells, though often pretty, are not gaudy or attractive, except in rare instances. The same may be said with almost equal truth of our marine crustaceans, though, on close inspection, the elegance of device on the carapaces of many species is exceedingly admirable."

Our fishes are not distinguished by brilliancy of colour. "Their hues are quaker-like, though sufficiently lustrous for sober tinting. The cod and flounder tribes are among the most characteristic, and such of the more common fishes as belong to families of which we have but few representatives are in most instances clothed in sober grey and silver. Beauty of no mean description may, however, be displayed by these modest vestments; as, for instance, in the mackerel and the herring. Our gorgeously decorated wrasses form the chief exception to the general rule, but these belong to a family more characteristic of the southern seas. A like deficiency in the numbers of the gurnard and mackerel tribes seriously affects the aspect of our piscine fauna when compared with denizens of the Mediterranean." The sharks and rays too are comparatively deficient, although a few species, as we have seen in a former chapter, are, to the great annoyance of our fishermen, over-abundant. The sea-eels are also few, though in the common conger and the larger sand-eel (_Ammodytes lancea_) we have two very conspicuous species.

As the surface of the British islands exhibits a transition as it were from a northern to a southern character, from the firs of Scotland to the free-growing myrtles of the Devon coast, so the inhabitants of our seas pass through a great variety of form, from a northern to a southern type. While the rorqual of the Frozen Ocean not seldom strands on our northern and eastern coasts; the flying-fish of the equinoctial seas sometimes appears within view of our southern shores; and it is this peculiar position of our insular empire, fronting the colder and the warmer seas, which enriches its waters with such a variety of marine life. "Several characteristic boreal forms find their southern limit within the northern half of our waters, and there some of the most striking and abundant kinds are chiefly developed in numbers, such as the cat-fish or sea-wolf (_Anarhicas lupus_), the scythe (_Merlangus carbonarius_), the ling (_Lota molva_), the cod (_Gadus morrhua_), the lump-sucker (_Cyclopterus lumpus_), and even the herring (_Clupea harengus_). On the other hand, along the southern shores of England we find fishes becoming frequent which are distinctly of a southern type, such as the grey and red mullets (_Mugil cephalus_ and _Mullus barbatus_), the sea-bream, and, far more plentifully, the John Dory (_Zeus aper_) and the pilchard (_Clupea pilchardus_)."[V]

[Footnote V: Godwin Austen, Natural History of the European Seas, pp. 103, 104.]

Although very inferior in beauty to the tropical fishes, our finny tribes are far superior in flavour, and may well challenge the world to produce their equals for the table. The turbot, cod, whiting, herring, whitebait, mackerel, sole, and even the salmon, though it belongs rather to fluviatile history than to the chronicles of the sea, may fairly be cited to testify to the truth of this assertion; so that surely we have no reason to complain of having been but indifferently provided for in the geographical distribution of fishes, which of all marine productions are the most important to man.

The researches of Forbes led him to believe that "as we descend deeper and deeper, the denizens of the sea become fewer and fewer, indicating our approach towards a silent and desolate abyss, where life is either extinguished or exhibits but faint glimmerings to mark its lingering presence;" but subsequent deep-sea soundings, performed with improved dredging apparatuses, have led to the surprising result that the bottom of the ocean, even in its abyssal depths, far from being a dreary void, as was formerly imagined, is in reality a busy scene, absolutely teeming with life. And in this case, as in so many others, we have a fine instance of the truth of the observation that every new invention or discovery casts a new light upon some other province of human knowledge; for to the submarine telegraph we are indebted for the first certain proof of the existence of highly organised animals living at abyssal depths.

In 1860 the submarine cable between Sardinia and Bona, on the coast of Africa, having completely failed, was picked up from a depth exceeding one thousand fathoms, and found encrusted with various shells and corals. All previous observations with reference to the existence of living creatures at extreme depths had been liable to doubt from two sources. In the first place the methods of deep-sea soundings were still so imperfect that there was always a possibility, from the action of deep currents upon the sounding-line or from other causes, of a greater depth being indicated than really existed; and, secondly, there was no absolute certainty that the animals entangled on the sounding instrument had actually come up from the bottom. They might have been caught on the way.

But now all doubt was removed. A submarine cable lies on the ground throughout its whole length. Before laying it, its course is carefully surveyed and the real depth accurately ascertained. Fishing it up is a delicate and difficult operation, and during its progress the depth is checked again and again. When, therefore, as in this case, the animals dragged up with a cable from depths of upwards of one thousand fathoms are found, not sticking loosely to it, but moulded upon its outer surface, or cemented to it by horny or calcareous excretions, it is evident that they must have lived and grown upon it at the bottom of the deep sea.

The subsequent dredging cruises of H.M.SS. "Porcupine" and "Lightning" in 1868, 1869, and 1870, under the scientific direction of Dr. Carpenter, Professor Wyville Thomson, and Mr. Gwyn Jeffreys, afforded additional and convincing proofs that life abounds in the abyssal regions of the ocean. During these several cruises 57 hauls of the dredge were taken at depths beyond 500 fathoms, and 16 at depths beyond 1,000 fathoms, and in all cases life was abundant. In 1869 two casts were taken in depths greater than 2,000 fathoms, and proved equally successful in bringing up specimens of deep-sea life. With the deepest cast, 2,435 fathoms, off the mouth of the Bay of Biscay, living, well-marked, and characteristic specimens of all the five invertebrate sub-kingdoms were taken. "And thus," says Professor Wyville Thomson,[W] "the question of the existence of abundant animal life at the bottom of the sea has been finally settled, and for all depths, for there is no reason to suppose that the depth anywhere exceeds between three and four thousand fathoms; and if there be nothing in the conditions of a depth of 2,500 fathoms to prevent the full development of a varied fauna, it is impossible to suppose that even an additional 1,000 fathoms would make any great difference."

[Footnote W: The Depths of the Sea. London, 1873.]

It may be asked how the deep-sea animals bear the enormous pressure at these great depths, which seems at first sight alone sufficient to put any idea of life out of the question? There was a curious popular notion that on descending deeper and deeper the sea water became gradually, under the pressure, heavier and heavier, so that at last it became more weighty than molten gold. But water is, in fact, almost incompressible; so that its density at 2,000 fathoms is scarcely appreciably increased. Any free air suspended in the water, or contained in any compressible tissue of an animal at 2,000 fathoms, would of course be reduced to a mere fraction of its bulk; but the animals subject to the pressure of the deep seas, being permeated throughout their whole organisation by incompressible fluids at the same pressure, are consequently as capable of bearing it as we do the pressure of the atmosphere. The absence of light seemed another circumstance incompatible with the existence of animal life at abyssal depths, as all plants depend upon light for their growth, and their absence apparently involves that of vegetable food, which, as we all know, forms everywhere the substratum of animal existence. We have as yet very little exact knowledge as to the distance to which the sun's light penetrates into the water of the sea. According to some recent experiments it would appear that the rays capable of affecting a delicate photographic film are very rapidly cut off, their effect being imperceptible at the depth of only a few fathoms; and though probably some portions of the sun's light possessing certain properties may penetrate to a much greater distance, it is certain that, beyond the first fifty fathoms, plants to whose existence light is essential are barely represented, and after two hundred fathoms entirely absent.

But though plant-life is thus limited to the more superficial parts of the ocean, the analysis of sea water, taken in all localities and at all depths, has shown that it everywhere contains a very appreciable and very uniform quantity of organic matter in solution and in suspension. It is thus quite intelligible that numberless protozoa--whose distinctive character is that they are capable of being supported by the absorption of organic matter through the surface of their bodies--are able to exist in the dark abysses of the sea, and in their turn afford nourishment to more highly organised animals.

After these general remarks on the creatures of the deep, I will now give a brief account of their various groups.

Over an enormous extent the abyssal ocean bottom is found covered with a sheet of almost formless beings, absolutely devoid of internal structure, and consisting merely of living and moving expansions of jelly-like matter. Whether this form of life, still more simple than the Amœba,[X] to which Professor Huxley has given the name of _Bathybius Haeckelii_, be continuous in one vast sheet or broken up into circumscribed individual particles, it is equally an object of wonder; and as no living thing, however slowly it may live, is ever perfectly at rest, it shows us that the bottom of the sea is, like its surface, the theatre of perpetual change.

[Footnote X: See Chapter XVIII., p. 380.]

Living among and upon this Bathybius we find a multitude of other protozoa, foraminifera and other rhizopods, radiolarians, and sponges.

Such is the countless number of the Foraminifera inhabiting the deep seas, that their remains form the chief mass of the soft oozy bottom of the ocean. In the surface layer of the deposit the shells of _Globigerina bulloides_, the prevailing species, are found fresh, whole, and living, and in the lower layers dead and gradually crumbling down by the decomposition of their organic cement and by the pressure of the layers above. Countless generations are thus piled one upon the other; and each successive stratum, weighing upon those of older date, is laying the foundation of future rocks, which subsequent revolutions may perhaps heave out of the deep and raise in towering pinnacles to the skies.

Sponges[Y] of wonderful beauty and lustre appear to extend in endless variety over the whole of the bottom of the sea. Some (_Holtenia Carpenteri_) anchor in the ooze by means of a perfect maze of delicate glassy filaments, like fine white hair, spreading out in all directions through the sea's fluid mud; while others (_Hyalonema_) send right down a coiled whisp of strong spicules, each as thick as a knitting-needle, which open out into a brush as the bed gets firmer, and fix the sponge in its place somewhat on the principle of a screw-pile. "A very singular sponge, from deep water off the Loffoden Islands, spreads into a thin circular cake, and adds to its surface by sending out a flat border of silky spicules, like a fringe of white floss silk round a little yellow mat; and the lovely Euplectella, whose beauty is imbedded up to its fretted lid in the grey mud of the seas of the Philippines, is supported by a frill of spicules standing up round it like Queen Elizabeth's ruff."[Z]

[Footnote Y: Ibid. pp. 385-389.]

[Footnote Z: The Depths of the Sea, p. 73.]

The stalked sea-stars, which, as the fossil pentacrinites and encrinites testify, abounded in the past periods of the earth's history, were, until now, supposed to be on the verge of extinction; but when we consider that the first few scrapes of the dredge at great depths have brought new species to light, we are entitled to believe that they constitute an important element in the abyssal fauna, and probably pave large tracts of the sea-bottom with a carpet of animated flowers. Freely-moving sea-stars and sea-urchins have likewise been hauled up in great numbers from abyssal depths; crustaceans have not been found wanting, and the captured shell-fish have shown that the deep-sea molluscs are by no means deficient in colour, though as a rule they are paler than those from shallow water.

_Dacrydium vitreum_, dredged from 2,435 fathoms, a curious little mytiloïd shell-fish, which makes and inhabits a delicate flask-shaped tube of foraminifera and other foreign bodies cemented together by organic matter and lined by a delicate membrane, is of a fine reddish-brown colour dashed with green, and the animals of one or two species of Lima from extreme depths are of the usual vivid orange scarlet.

Some of the abyssal molluscs have even been found provided with organs of sight. A new species of Pleurotoma, from 2,090 fathoms, had a pair of well-developed eyes on short foot-stalks, and a Fusus from 1,207 fathoms was similarly provided. The presence of organs of sight at these great depths leaves little room to doubt that light must reach even these abysses from some source, and as from many considerations it can scarcely be sunlight, Professor Wyville Thomson throws out the suggestion "that the whole of the light beyond a certain depth may be due to phosphorescence, which is certainly very general, particularly among the larvæ and young of deep-sea animals."

Thus many of the creatures dredged in the Northern Atlantic, off the west coast of Ireland,[AA] in depths varying from 557 to 584 fathoms, were most brilliantly phosphorescent. In some places nearly everything brought up seemed to emit light, and the mud itself was perfectly full of luminous specks. The alcyonarians, the brittle-stars, and some annelids were the most brilliant. The Pennatidæ, the Virgulariæ, and the Gorgoniæ shone with a lambent white light, so bright that it showed quite distinctly the hour on a watch, while the light from _Ophiacantha spinulosa_ was of a brilliant green, coruscating from the centre of the disk, now along one arm, now along another, and sometimes vividly illuminating the whole outline of the star-fish. While the Ophiacantha shines like a star of the most vivid uranium green, the sea-pen (_Pavonaria quadrangularis_) is resplendent with a pale lilac phosphorescence like the flame of cyanogen gas, not scintillating like the green light of Ophiacantha, but almost constant, sometimes flashing out at one point more vividly, and then dying gradually into comparative dimness, but still sufficiently bright to make every portion of the polyp visible.

[Footnote AA: Ibid., Chapter III. Cruise of the "Porcupine," pp. 98-149.]

Such numbers of the Pavonaria were brought up at one haul of the dredge in the Sound of Skye, that the "Porcupine" had evidently passed over a forest of them. While the darkness of winter frowns over the surface of the Northern Atlantic, the animated shrubs at its bottom are thus glowing with light, and a kind of magical day prevails in depths which were supposed to be shrouded with perpetual night. But it might have been better for many of the luminous denizens of the abyss if a more obscure existence had been their lot; for in a sea swarming with predaceous crustaceans with great bright eyes phosphorescence must surely be a fatal gift.

Off the coast of Portugal there is a great fishery of sharks (_Centroscymnus Cœlolepis_), carried on at a depth of 500 fathoms. If an animal so highly organised as a shark can thus bear without inconvenience the enormous pressure of more than half a ton on the square inch existing at that depth, it is a sufficient proof that the pressure is applied under circumstances which prevent its affecting it to its prejudice, and there seems to be no reason why it should not tolerate equally well a pressure of one or two tons, or why many other fishes--though the dredge, in consequence of their facility of locomotion, will hardly ever be able to bring them to light--should not abound in the still waters of the abyssal deep.

The "Challenger" Exploring Expedition will no doubt reveal to us still many an unknown wonder of those interesting regions, and make us acquainted with a world of new animals which even the profundity of the ocean vainly strives to hide from the curiosity of man.

CHAP. XXI.

THE PHOSPHORESCENCE OF THE SEA.

Its Causes.--Noctiluca miliaris.--Phosphorescent Annelides and
Beroës.--Intense Phosphorescence of the Pyrosoma atlantica.--Luminous
Pholades.--The luminous Shark.--Phosphorescent Algæ.--Citations from
Byron, Coleridge, and Crabbe.

He who still lingers on the shore after the shades of evening have descended, not seldom enjoys a most magnificent spectacle; for lucid flashes burst from the bosom of the waters, as if the sea were anxious to restore to the darkened heavens the light it had received from them during the day. On approaching the margin of the rising flood to examine more closely the sparkling of the breaking wave, the spreading waters seem to cover the beach with a sheet of fire. Each footstep over the moist sands elicits luminous star-like points, and a splash in the water resembles the awakening of slumbering flames.

The same wonderful and beauteous aspect frequently gladdens the eye of the navigator who ploughs his way through the wide deserts of ocean, particularly if his course leads him through the tropical seas.

"When a vessel," says Humboldt, "driven along by a fresh wind, divides the foaming waters, one never wearies of the lovely spectacle their agitation affords; for, whenever a wave makes the ship incline sideways, bluish or reddish flames seem to shoot upwards from the keel. Beautiful beyond description is the sight of a troop of dolphins gambolling in the phosphorescent sea. Every furrow they draw through the waters is marked by streaks of intense light. In the Gulf of Cariaco, between Cumana and the peninsula of Maniquarez, this scene has often delighted me for hours."

But even in the colder oceanic regions the brilliant phenomenon appears from time to time in its full glory. During a dark and stormy September night, on the way from the Sea-lion island, Saint George, to Unalaschka, Chamisso admired as beautiful a phosphorescence of the ocean as he had ever witnessed in the tropical seas. Sparks of light, remaining attached to the sails that had been wetted by the spray, continued to glow in another element. Near the south point of Kamtschatka, at a water-temperature hardly above freezing point, Ermann saw the sea no less luminous than during a seven months' sojourn in the tropical ocean. This distinguished traveller positively denies that warmth decidedly favours the luminosity of the sea.

At Cape Colborn, one of the desolate promontories of the desolate Victoria Land, the phosphoric gleaming of the waves on the 6th September, when darkness closed in, was so intense that Simpson assures us he had seldom seen anything more brilliant. The boats seemed to cleave a flood of molten silver, and the spray dashed from their bows, before the fresh breeze, fell back in glittering showers into the deep.

Mr. Charles Darwin paints in vivid colours the magnificent spectacle presented by the sea, while sailing in the latitudes of Cape Horn on a very dark night.

There was a fresh breeze, and every part of the surface, which during the day is seen as foam, now glowed with a pale light. The vessel drove before her bows two billows of liquid phosphorus, and in her wake she was followed by a milky train. As far as the eye reached, the crest of every wave was bright, and the sky above the horizon, from the reflected glare of these livid flames, was not so utterly obscure as over the rest of the heavens.

While "La Venus" was at anchor before Simon's Town, the breaking of the waves produced so strong a light that the room in which the naturalists of the expedition were seated was illumined as by sudden flashes of lightning. Although more than fifty paces from the beach where the phenomenon took place, they tried to read by this wondrous oceanic light, but the successive glimpses were of too short duration to gratify their wishes.

Thus we see the same nocturnal splendour which shines forth in the tropical seas, and gleams along our shores, burst forth from the arctic waters, and from the waves that bathe the southern promontories of the old and the new worlds.

But what is the cause of the beautiful phenomenon so widely spread over the face of ocean? How comes it that at certain times flames issue from the bosom of an element generally so hostile to their appearance?

Without troubling the reader with the groundless surmises of ancient naturalists, or repeating the useless tales of the past, I shall at once place myself with him on the stage of our actual knowledge of this interesting and mysterious subject. It is now no longer a matter of doubt that many of the inferior marine animals possess the faculty of secreting a luminous matter, and thus adding their mite to the grand phenomenon. When we consider their countless multitudes, we shall no longer wonder at such magnificent effects being produced by creatures individually so insignificant.

In our seas it is chiefly a minute gelatinous animal, the _Noctiluca miliaris_, most probably an aberrant member of the infusorial group, which, as it were, repeats the splendid spectacle of the starry heavens on the surface of the ocean. In form it is nearly globular, presenting on one side a groove, from the anterior extremity of which issues a peculiar curved stalk or appendage, marked by transverse lines, which might seem to be made use of as an organ of locomotion. Near the base of this tentacle is placed the mouth, which passes into a dilatable digestive cavity, leading, according to Mr. Huxley, to a distinct anal orifice. From the rather firm external coat proceed thread-like prolongations through the softer mass of the body, so as to divide it into irregular chambers. This little creature, which is just large enough to be discerned by the naked eye when the water in which it may be swimming is contained in a glass jar exposed to the light, seems to feed on diatoms, as their loricæ may frequently be detected in its interior. It multiplies by spontaneous fission, and the rapidity of this process may be inferred from the immensity of its numbers. A single bucket of luminous sea-water will often contain thousands, while for miles and miles every wave breaking on the shore expands in a sheet of living flame. It was first described by Forster in the Pacific Ocean; it occurs on all the shores of the Atlantic, and the Polar Seas are illuminated by its fairy light. "The nature of its luminosity," says Dr. Carpenter, "is found by microscopic examination to be very peculiar; for what appears to the eye to be a uniform glow is resolvable under a sufficient magnifying power into a multitude of evanescent scintillations, and these are given forth with increased intensity whenever the body of the animal receives any mechanical shock."

The power of emitting a phosphorescent light is widely diffused both among the free-swimming and the sessile Cœlenterata. Many of the Physophoridæ are remarkable for its manifestation, and a great number of the jelly-fishes are luminous. Our own _Thaumantias lucifera_, a small and by no means rare medusid, displays the phenomenon in a very beautiful manner, for, when irritated by contact of fresh water, it marks its position by a vivid circlet of tiny stars, each shining from the base of a tentacle. A remarkable greenish light, like that of burning silver, may also be seen to glow from many of our Sertularians, becoming much brighter under various modes of excitation.

Among the Ctenophora the large _Cestum Veneris_ of the Mediterranean is specially distinguished for its luminosity, and while moving beneath the surface of the water gleams at night like a brilliant band of flame.

The Sea-pens are eminently phosphorescent, shining at night with a golden-green light of a most wonderful softness. When touched, every branchlet above the shock emits a phosphoric glow, while all the polyps beneath remain in darkness. When thrown into fresh water or alcohol, they scatter sparks about in all directions, a most beautiful sight; dying, as it were, in a halo of glory.

But of all the marine animals the Pyrosomas, doing full justice to their name (fire-bodies) seem to emit the most vivid coruscations. Bibra relates in his "Travels to Chili" that he once caught half a dozen of these remarkable light-bearers, by whose phosphorescence he could distinctly read their own description in a naturalist's vade-mecum. Although completely dark when at rest the slightest touch sufficed to elicit their clear blue-green light. During a voyage to India, Mr. Bennett had occasion to admire the magnificent spectacle afforded by whole shoals of Pyrosomas. The ship, proceeding at a rapid rate, continued during an entire night to pass through distinct but extensive fields of these molluscs, floating and glowing as they floated on all sides of her course. Enveloped in a flame of bright phosphorescent light, and gleaming with a greenish lustre, the Pyrosomes, in vast sheets, upwards of a mile in breadth, and stretching out till lost in the distance, presented a sight, the glory of which may be easily imagined. The vessel, as it cleaved the gleaming mass, threw up strong flashes of light, as if ploughing through liquid fire, which illuminated the hull, the sails, and the ropes, with a strange unearthly radiance.

In his memoir on the Pyrosoma, M. Péron describes with lively colours the circumstances under which he first made its discovery, during a dark and stormy night, in the tropical Atlantic. "The sky," says this distinguished naturalist, "was on all sides loaded with heavy clouds; all around the obscurity was profound; the wind blew violently, and the ship cut her way with rapidity. Suddenly we discovered at some distance a great phosphorescent band stretched across the waves, and occupying an immense tract in advance of the ship. Heightened by the surrounding circumstances, the effect of this spectacle was romantic, imposing, sublime, rivetting the attention of all on board. Soon we reached the illuminated tract, and perceived that the prodigious brightness was certainly and only attributable to the presence of an innumerable multitude of largish animals floating with the waves. From their swimming at different depths they took apparently different forms: those at the greatest depth were very indefinite, presenting much the appearance of great masses of fire, or rather of enormous red-hot cannon balls; whilst those more distinctly seen near the surface perfectly resembled incandescent cylinders of iron.

"Taken from the water, these animals entirely resembled each other in form, colour, substance, and the property of phosphorescence, differing only in their sizes, which varied from three to seven inches. The large, longish tubercles with which the exterior of the Pyrosomes was bristled were of a firmer substance, and more transparent than the rest of the body, and were brilliant and polished like diamonds. These were the principal scene of phosphorescence. Between these large tubercles, smaller ones, shorter and more obtuse, could be distinguished; these also were phosphorescent. Lastly, in the interior of the substance of the animal, could be seen, by the aid of the transparency, a number of little, elongated, narrow bodies (viscera), which also participated in a high degree in the possession of the phosphoric light."

In the Pholades or Lithodomes, that bore their dwellings in the hard stone, as other shell-fish do in the loose sands, the whole mass of the body is permeated with light. Pliny gives us a short but animated description of the phenomenon in the edible date-shell of the Mediterranean (_Pholas dactylus_):--

"It is in the nature of the pholades to shine in the darkness with their own light, which is the more intense as the animal is more juicy. While eating them, they shine in the mouth and on the hands, nay, even the drops falling from them upon the ground continue to emit light, a sure proof that the luminosity we admire in them is associated with their juice." Milne-Edwards found this observation perfectly correct, for wishing to place some living pholades in alcohol, he saw a luminous matter exude from their bodies, which on account of its weight sank in the liquid, covering the bottom of the vessel, and there forming a deposit as shining as when it was in contact with the air.

Several kinds of fishes likewise possess the luminous faculty. The sun-fish, that strange deformity, emits a phosphoric gleam; and a species of Gurnard (_Trigla lucerna_) is said to sparkle in the night, so as to form fiery streams through the water.

With regard to the luminosity of the larger marine animals, Ermann, however, remarks that he so often saw small luminous crustacea in the abdominal cavity of the transparent _Salpa pinnata_, that it may well be asked whether the phosphorescence of the larger creatures is not in reality owing to that of their smaller companions.

According to Mr. Bennett, "Whaling Voyage round the Globe," a species of shark first discovered by himself is distinguished by an uncommonly strong emission of light. When the specimen, taken at night, was removed into a dark apartment, it afforded a very interesting spectacle. The entire inferior surface of the body and head emitted a vivid and greenish phosphorescent gleam, imparting to the creature by its own light a truly ghastly and terrific appearance. The luminous effect was constant, and not perceptibly increased by agitation or friction. When the shark expired, (which was not until it had been out of the water more than three hours,) the luminous appearance faded entirely from the abdomen, and more gradually from other parts; lingering longest around the jaws and on the fins.

The only part of the under surface of the animal which was free from luminosity was the black collar round the throat; and while the inferior surface of the pectoral, anal, and caudal fins shone with splendour, their superior surface (including the upper lobe of the tail fin) was in darkness, as were also the dorsal fins, and the back and summit of the head.

Mr. Bennett is inclined to believe that the luminous power of this shark resides in a peculiar secretion from the skin. It was his first impression that the fish had accidentally contracted some phosphorescent matter from the sea, or from the net in which it was captured; but the most rigid investigation did not confirm this suspicion, while the uniformity with which the luminous gleam occupied certain portions of the body and fins, its permanence during life, and decline and cessation upon the approach and occurrence of death, did not leave a doubt in his mind but that it was a vital principle essential to the economy of the animal. The small size of the fins would appear to denote that this fish is not active in swimming; and, since it is highly predaceous and evidently of nocturnal habits, we may perhaps indulge in the hypothesis, that the phosphorescent power it possesses is of use to attract its prey, upon the same principle as the Polynesian islanders and others employ torches in night-fishing.

Some of the lower sea-plants also appear to be luminous. Thus, over a space of more than 600 miles (between lat. 8° N. and 2° S.), Meyen saw the ocean covered with phosphorescent Oscillatoria, grouped together into small balls or globules, from the size of a poppy-seed to that of a lentil.

But if the luminosity of the ocean generally proceeds from living creatures, it sometimes also arises from putrefying organic fibres and membranes, resulting from the decomposition of those living light-bearers. "Sometimes," says Humboldt, "even a high magnifying power is unable to discover any animals in the phosphorescent water, and yet light gleams forth wherever a wave strikes against a hard body and dissolves in foam. The cause of this phenomenon lies then most likely in the putrefying fibres of dead mollusks, which are mixed with the waters in countless numbers."

Summing up the foregoing in a few words, it is thus an indisputable fact, that the phosphorescence of the sea is by no means an electrical or magnetic property of the water, but exclusively bound to organic matter, living or dead. But although thus much has been ascertained, we have as yet only advanced one step towards the unravelling of the mystery, and its proximate cause remains an open question. Unfortunately, science is still unable to give a positive answer, and we are obliged to be contented with a more or less plausible hypothesis. When we consider that the phosphorescence most commonly resides only in the outward mucous covering of the body, in which a number of particles cast off by the skin are continually undergoing decomposition, the phenomenon seems to be a simple chemical process, during which more or less phosphorus may be disengaged, which by agitation or friction gives rise to the emission of light. It is more difficult to explain those cases in which the entire mass of the body is luminous (as in Pholas), or the muscular substance (as in some Annelides), or the vibratory cilia (as in the Beroës); and here we do better to confess our entire ignorance, than to resort to the hypothesis of electrical discharges, extremely improbable in an element which is so excellent an electrical conductor, and particularly when we consider that no emission of light takes place in the few and powerful electrical fishes we are acquainted with.

We know as little of what utility marine phosphorescence may be. Why do the countless myriads of Mammariæ gleam and sparkle along our coasts? Is it to signify their presence to other animals, and direct them to the spot where they may find abundance of food? So much is certain, that so grand and wide-spread a phenomenon must necessarily serve some end equally grand and important.

As the phosphorescence of the sea is owing to living creatures, it must naturally show itself in its greatest brilliancy when the ocean is at rest; for during the daytime we find the surface of the waters most peopled with various animals when only a slight zephyr glides over the sea. In stormy weather, the fragile or gelatinous world of the lower marine creatures generally seeks a greater depth, until the elementary strife has ceased, when it again loves to sport in the warmer or more cheerful superficial waters.

In the tropical zone, Humboldt saw the sea most brilliantly luminous before a storm, when the air was sultry, and the sky covered with clouds. In the North Sea we observe the phenomenon most commonly during fine tranquil autumnal nights; but it may be seen at every season of the year, even when the cold is most intense. Its appearance is, however, extremely capricious; for, under seemingly unaltered circumstances, the sea may one night be very luminous, and the next quite dark. Often months, or even years, pass by without witnessing it in full perfection. Does this result from a peculiar state of the atmosphere, or do the little animals love to migrate from one part of the coast to another?

It is remarkable that the ancients should have taken so little notice of oceanic phosphorescence. The "Periplus" of Hanno contains perhaps the only passage in which the phenomenon is described. To the south of Cerne the Carthaginian navigator saw the sea burn, as it were, with streams of fire. Pliny, in whom the miracle (_miraculum_, as he calls it) of the date-shell excited so lively an admiration, and who must often have seen the sea gleam with phosphoric light, as the passage proves where he mentions in a few dry words the luminous gurnard (_lucerna_) stretching out a fiery tongue, has no exclamation of delight for one of the most beautiful sights in nature. Homer also, who has given us so many charming descriptions of the sea in its ever-changing aspects, and who so often leads us with long-suffering Ulysses through the nocturnal floods, never once makes them blaze or sparkle in his immortal hexameters.

Even modern poets mention the phenomenon but rarely. Camoens himself, whom Humboldt, on account of his beautiful oceanic descriptions, calls, above all others, the "poet of the sea," forgets to sing it in his Lusiad. Byron in his "Corsair" has a few lines on the subject:

"Flash'd the dipt oars, and, sparkling with the stroke,
Around the waves phosphoric brightness broke;"

but contents himself, as we see, with coldly mentioning a phenomenon so worthy of all a poet's enthusiasm. In Coleridge's wondrous ballad of "The ancient Mariner" we find a warmer description:

"Beyond the shadow of the ship
I watch'd the water-snakes:
They moved in tracks of shining white,
And, when they rear'd, the elfish light
Fell off in hoary flakes.

"Within the shadow of the ship
I watch'd their rich attire--
Blue, glossy green, and velvet black:
They coiled and swam, and every track
Was a flash of golden fire."

These indeed are lines whose brilliancy emulates the splendour of the phenomenon they depict, but even they are hardly more beautiful than Crabbe's admirable description:

"And now your view upon the ocean turn,
And there the splendour of the waves discern;
Cast but a stone, or strike them with an oar,
And you shall flames within the deep explore;
Or scoop the stream phosphoric as you stand,
And the cold flames shall flash along your hand;
When, lost in wonder, you shall walk and gaze
On weeds that sparkle, and on waves that blaze."

Or than the graphic numbers of Sir Walter Scott:

"Awak'd before the rushing prow,
The mimic fires of ocean glow,
Those lightnings of the wave;
Wild sparkles crest the broken tides.
And flashing round, the vessel's sides
With elfish lustre lave;
While, far behind, their livid light
To the dark billows of the night
A blooming splendour gave."

CHAP. XXII.

THE PRIMITIVE OCEAN.

The Giant-Book of the Earth-rind.--The Sea of Fire.--Formation of a
solid Earth-crust by cooling.--The Primitive Waters.--First awakening
of Life in the Bosom of the Ocean.--The Reign of the Saurians.--The
future Ocean.

The greatest of all histories, traced in mighty characters by the Almighty himself, is that of the earth-rind. The leaves of this giant volume are the strata which have been successively deposited in the bosom of the sea, or raised by volcanic powers from the depths of the earth; the wars which it relates are the Titanic conflicts of two hostile elements, water and fire, each anxious to destroy the formations of its opponent; and the historic documents which bear witness to that ancient strife lie before us in the petrified or carbonified remains of extinct forms of organic existence--the medals of creation.

It is only since yesterday that science has attempted to unriddle the hieroglyphics in which the past history of our planet reveals itself to man, and it stands to reason that in so difficult a study truth must often be obscured by error; but although the geologist is still a mere scholar, endeavouring to decipher the first chapters of a voluminous work, yet even now the study of the physical revolutions of our globe distinctly points out a period when the molten earth wandered, a ball of liquid fire, through the desert realms of space. In those times, so distant from ours that even the wildest flight of imagination is unable to carry us over the intervening abyss, the waters of the ocean were as yet mixed with the air, and formed a thick and hazy atmosphere through which no radiant sunbeam, no soft lunar light, ever penetrated to the fiery billows of molten rock, which at that time covered the whole surface of the earth. What pictures of desolation rise before our fancy, at the idea of yon boundless ocean of fluid stone, which rolled from pole to pole without meeting on its wide way anything but itself. Ever and ever in the dark-red clouds shone the reflection of that vast conflagration, witnessed only by the eye of the Almighty, for organic life could not exist on a globe which exclusively obeyed the physical and chemical laws of inorganic nature.

But while the fiery mass with its surrounding atmosphere was circling through the icy regions of ethereal space (the temperature of which is computed to be lower than 60° R. below freezing point), it gradually cooled, and its hitherto fluid surface began to harden to a solid crust. Who can tell how many countless ages may have dropped one after the other into the abyss of the past, ere thus much was accomplished; for the dense atmosphere constantly threw back again upon the fiery earth-ball the heat radiating from its surface, and the caloric of the vast body could escape but very slowly into vacant space?

Thus millions of years may have gone by before the aqueous vapours, now no longer obstinately repelled by the cooling earth-rind, condensed into rain, and, falling in showers, gave birth to an incipient ocean. But it must not be supposed that the waters obtained at once a tranquil and undisturbed possession of their new domain, for, as soon as they descended upon the earth, those endless elementary wars began, which, with various fortunes, have continued to the present day.

As soon as the cooling earth-rind began to harden, it naturally contracted, like all solid bodies when no longer subject to the influence of expanding heat, and thus in the thin crust enormous fissures and rents were formed, through which the fluid masses below gushed forth, and, spreading in wide sheets over the surface, once more converted into vapours the waters they met with in their fiery path.

But after all these revolutions and vicissitudes which opposed the birth of ocean, perpetually destroying its perpetually renewed formation, we come at last to a period when, in consequence of the constantly decreasing temperature of the earth-rind, and its increasing thickness, the waters at last conquered a permanent abode on its surface, and the oceanic empire was definitively founded.

The scene has now changed; the sea of fire has disappeared, and water covers the face of the earth. The rind is still too thin, and the eruptions from below are still too fluid to form higher elevations above the general surface: all is flat and even, and land nowhere rises above the mirror of a boundless ocean.

This new state of things still affords the same spectacle of dreary uniformity and solitude in all its horrors. The temperature of the waters is yet too high, and they contain too many extraneous substances, too many noxious vapours arise from the clefts of the earth-rind, the dense atmosphere is still too much impregnated with poisons, to allow the hidden germs of life anywhere to awaken. A strange and awful primitive ocean rises and falls, rolls and rages, but nowhere does it beat against a coast; no animal, no plant, grows and thrives in its bosom; no bird flies over its expanse.

But meanwhile the hidden agency of Providence is unremittingly active in preparing a new order of things. The earth-rind increases in thickness, the crevices become narrower, and the fluid or semi-fluid masses escaping through the clefts ascend to a more considerable height.

Thus the first islands are formed, and the first separation between the dry land and the waters takes place. At the same time no less remarkable changes occur, as well in the constitution of the waters as in that of the atmosphere. The farther the glowing internal heat of the planet retires from the surface, the greater is the quantity of water which precipitates itself upon it. The ocean, obliged to relinquish part of its surface to the dry land, makes up for the loss of extent by an increase of depth, and the clearer atmosphere allows the enlivening sunbeam to gild here the crest of a wave, there a naked rock.

And now also life awakens in the seas, but how often has it changed its forms, and how often has Neptune displaced his boundaries since that primordial dawn. Alternately rising or subsiding, what was once the bottom of the ocean now forms the mountain crest, and whole islands and continents have been gradually worn away and whelmed beneath the waves of the sea, to arise and to be whelmed again. In every part of the world we are able to trace these repeated changes in the fossil remains embedded in the strata that have successively been deposited in the sea, and then again raised above its level by volcanic agencies, and thus, by a wonderful transposition, the history of the primitive ocean is revealed to us by the tablets of the dry land. The indefatigable zeal of the geologists has discovered no less than thirty-nine distinct fossiliferous strata of different ages, and as many of these are again subdivided into successive layers, frequently of a thickness of several thousand feet, and each of them characterised by its peculiar organic remains, we may form some idea of the vast spaces of time required for their formation.