Part 9 (2/2)
We have given the above quotation at full length, because it proves, in an interesting manner, the fact that phosph.o.r.escence, or luminosity, of the sea is actually produced by mult.i.tudes of living creatures. We cannot pa.s.s from it, however, without expressing our difference of opinion in regard to the power of the medusae to emit their light ”at will.”
It seems much more probable that the light is the result of pa.s.sion and action. When a man's feelings are strongly roused, whether pleasurably or otherwise, he usually starts into action under a sudden impulse, which sends the blood violently through his veins, causing his face to become flushed and _red_. This reddening is not the result of will. It is the unavoidable result of pa.s.sionate impulse, and could not possibly be produced by an effort of the will.
It is well known that electric fluid permeates the bodies of all animals, more or less; and it is quite conceivable that under the influence of nervous impulse one creature should become luminous, while another only becomes red. Man leaps and sings for joy; and the result is, that the actions cause his countenance to glow with _colour_. The marine animalcule, experiencing a sudden influx of delight, darts. .h.i.ther and thither under the strong impulse of its exuberant glee; and the result is, that its little body gleams with _light_. Vigorous action is the direct cause of the emission of light in the one case, just as vigorous action is the direct cause of the suffusion of the countenance in the other. But in both cases the primary cause is pa.s.sion--at least so it seems to us.
No doubt fear as well as joy may create vigorous action, and produce the same result; but as we know that, as a general rule, there is much more of joy than of fear dwelling at all times in the hearts of G.o.d's creatures, we can well believe that the amount of luminosity produced in the sea by the latter pa.s.sion is immeasurably smaller than that produced by the former. We are thus, therefore, set free to indulge in the pleasing reflection that when we behold that magnificent gleaming of the sea, which almost resembles liquid silver reflecting the stars of heaven, we are witnessing the frolicsome and joyous gambols of those myriads of little beings to whom the beneficent Creator has a.s.signed the ocean as their dwelling-place.
The theory which we have ventured to propound in regard to vigorous impulse (whether of joy or fear) being the cause of eliciting luminosity, is supported in some degree by the remark in our last quotation, that when the bucket was sharply struck, there appeared at once a number of luminous bodies, which shone for a few seconds, and then disappeared. Undoubtedly the poor little things got a fright when their residence was sharply a.s.sailed in such an unusual manner; their energies were roused, and their light emitted. Then, as they gradually calmed down, their light disappeared.
We are further told that when a drop of sulphuric acid was put into a tumbler of water, ”several bright flashes were seen.” This, we venture to think, was somewhat similar to the putting of a few drops of brandy and water into the human stomach; the usual result of which is, as we all know, to produce several bright flashes of wit, if not of light, or of something at least meant to be remarkably luminous!
But this luminosity is not entirely confined to the minute creatures of the sea. Some fish have the power of emitting light. Some species of the shark emit a greenish light; and the sun-fish is said, when seen down in the sea on a dark night, to glow like a white-hot cannon-ball.
Fish when dead and putrid frequently glow in the dark with a truly magnificent light, as can be proved by every one who will take the trouble to procure several kinds of fish, and keep them, for the purpose of proving the fact, in a dark closet.
Of all the minute inhabitants of the deep, that which is to our mind the most curious, both as to its nature and its stupendous works, is the coral insect. This creature is much too important to be dragged in at the tail of a chapter. We will, therefore, commence its history in a new one.
CHAPTER FIFTEEN.
CORAL INSECTS AND CORAL ISLANDS--POLYNESIA--OPERATIONS OF THE CORAL INSECT--GROWTH OF CORAL REEFS.
Many of the large and beautiful islands that stud the Pacific Ocean, like emeralds in a field of blue, are _artificial_; that is to say, they were made by artists--they were actually _built_ by _artisans_!
These artisans are the coral insects; and as they not only affect the face of the sea by raising large islands above it, but also, in consequence of their labours, a.s.sist in causing the circulation of the ocean, we think they are justly ent.i.tled to very special attention.
The great archipelago called Polynesia covers an area of the Pacific nearly 5000 miles in length, and not far short of 2000 in breadth. Some of the islands of this group are of volcanic origin, and some are crystal; but by far the greater number are of coral formation--the work of those curious little insects, which are so small that they inhabit a dwelling sometimes little larger than a pin-point.
The manner in which these islands are made is, to some extent, a matter of uncertainty. The most generally received opinion is, that the insects fasten round the summit of a submarine mountain, and build upwards until they reach the surface of the sea, where they die, and their labours cease. As, however, the sea is sometimes unfathomable close to those islands, it has been supposed that the submarine islands on which the corallines began to build have gradually subsided, and that, as they did so, the insects always built a little more, so as to keep the top of their structures on a level with the sea. Above the sea they cannot build. To be washed by the waves is essential to their existence.
We do not think this a very satisfactory theory, because it supposes a prolonged subsiding of these islands, and then an unaccountably sudden stoppage. For although the corallines might continue to build during the whole time of subsidence, it were utterly impossible that the coral _island_, with its luxuriant herbage, could be formed until that subsidence should have ceased. The manner in which the islands are formed makes this obvious.
When the coral reef, as it is called, reaches the surface, it advances no further. Soon the action of the waves breaks off the branches of the upper portions of coral, which are tossed upon the reef, and pulverised into fine sand. This goes on increasing until the island rises a little above the waves.
When this happens, birds alight there; sea-drift is carried thither; seeds are blown to it by the wind; and gradually a few green blades arise. From this little beginning it is easy to conceive the process by which at last a flouris.h.i.+ng island springs up. At the same time, it is not easy to see how such islands could ever be formed on the supposition that the submarine rocks on which they were founded were perpetually subsiding.
But be that as it may, we have no difficulty in understanding the fact that the coral insect does build those islands. It possesses the power of secreting the lime held in solution by sea water, and depositing the same on the rocks below the waves. The coral rock is the edifice of the coralline. The insect itself is a soft and very minute worm, which, when washed by the waves, thrusts its head out of its tiny little door, and spreading abroad its numerous feelers, so that it resembles a beautiful little star, moves these about as if enjoying itself--though, doubtless, it is actually engaged in the process of manufacturing its little atom of coral rock.
It is extremely interesting to think of the immense power of _union_ thus exhibited. Singly, those little creatures could not produce a sufficient result to attract the attention of any creature save such as chanced to come in direct and close contact with its little cell.
United, they have formed vast islands, which have become the abode of man, and which, in the aggregate, form no inconsiderable portion of the globe.
The consideration of this leads us to perceive that G.o.d has ordained that units cannot, separately, accomplish much; and that united effort, in order to be successful, requires the harmonious action of units. ”A house divided against itself cannot stand.” The innumerable and eminently beautiful isles of the Pacific had never stood where they now stand if the curious, and separately insignificant, little architects that reared them had not wrought unitedly upon a fixed and systematic plan--each insect working its utmost from the hour of its birth until that of its death.
There are various kinds of coral insects, which form varied species of coral rock. Some kinds of coral a.s.sume the form of rounded ma.s.ses; some are like a branching shrub; others are in layers, or thin plates; and some are shaped like the human brain, from which they derive their name--brainstones. These different kinds differ also in colour, and thus present a beautiful appearance when seen at the bottom of clear and shallow water.
In regard to the rate at which the corallines build their cells there is some diversity of opinion--some a.s.serting that the process is imperceptible, while others state as positively that it is rapid. There can be no doubt that some localities and positions are more favourable to the growth of coral than others. Dr Allan, while at Madagascar, made several experiments to test this. He selected several ma.s.ses of coral, each weighing about ten pounds, and of different species. These he placed three feet below the surface of the sea, and staked them in to prevent removal. In a little more than six months they were found to have risen nearly to the surface, and to have attached themselves to the solid rock.
There is also a case mentioned of a s.h.i.+p in the Persian Gulf which, in the course of twenty months, had her copper encased with living coral to the thickness of two feet.
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