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They attach themselves to stones, and other solid bodies, and are concretions, formed by the Polype insects which inhabit them. They are, generally, of a plant-like form, with elevated branches, and exhibit an elegant appearance from their symmetry and proportions, being generally subdivided, calcareous, and composed of little joints, like beads strung on a necklace; which peculiarity easily distinguishes them from the Coral family. The joints are generally perforated, or full of minute cells; and in these the Polypes reside, the openings serving them as doorways, through which to seize their prey. When a branch is immersed in vinegar, the calcareous crust dissolves, and leaves the interior uninjured, by which means its beautiful formation may be easily examined.
This elegant species is highly ornamental in collections of natural history; and one of them, the Corallina Officinalis, is valuable in medicine. Fiftyseven species are well known ; some of which, are extremely beautiful; and others, of rare occurrence. They vary both in size and structure; for Nature is ever prodigal in the profusion of her embellishments :
« Some present
And fledged with snowy feathers, nod superb.”
of these interesting marine productions. They are often left by the receding of the tide upon the shore; and as often are seen to float by, on the sparkling waves, either attached to a group of thickly-matted sea-weed, a broken piece of wood, or the empty shell of a muscle. Some appear like little tufts of green grass, floating and trembling in the waves; others resemble bunches of hair-like tubes, varying from a greenish-brown to white: a few may be compared to clusters of diminutive beads, and a large proportion to long brown filaments, covered with a calcareous crust. Each of these is the separate habitation of a constructing agent, a minute world, enclosing joys and griefs, peculiarly its own; and as little or no difference subsists between the formation of Corals and Corallines by their respective inhabitants, I shall briefly state a few observations, with regard to the former.
These bodies, which previous naturalists imagined to be flowers, are ascertained to be insects inhabiting the Coral ; for upon taking a branch from the water, the seeming flowers, which proceed from a number of minute points answering to the holes that pierce the bark, and resemble the flower of an olive tree, enter into the bark, and disappear; but upon being again put into the water, they presently shoot forth. The openings in the bark, or rather of the stony crust, correspond to small cavities upon the substance of the Coral, and when removed, a variety of little tubes become visible, which connect the bark with the inner substance, as well as numerous glands that adhere to them. From these glands the milky juice of Coral issues; the holes in the bark, as already noticed, being the openings through which the Polypes come out. These curious insects dwell within the tubes, and the milky juice is always more abundant, in proportion to their health and vigour. This juice, or liquor, runs along the furrows, which are perceptible upon the substance of the Coral, and gradually becoming hard and fixed, changes into stone, and causes the Coral to increase in every direction.
In forming Coral, and other marine productions of a similar description, Polypiferous insects labour according to their species; while their proportions vary in accordance with their several forms, magnitudes, and colours. In short, Corals and Corallines have the same relation to the Polypes united with them, as subsists between the shell of the snail, and the snail itself.
These Polypes expand in water, and contract in air ; they evince considerable sensation when touched with the hand, or when exposed to the action of acids: they have even been seen to move their claws, and to expand themselves, when the water which contained them, was placed near the fire. A considerable number resemble, snails and lobsters, whilst others are slender, and several feet in length. The most common are wheel-shaped, with arms from four to six inches long, which they move rapidly, in order, as it is supposed, to catch food. Some are slow in their motions, a few exceedingly active. Some are of a dark colour; others are blue; and others again, bright yellow. Those of the Mediterranean are either red or white, or vermilion ; and on the shores of the island which Harvey has thus beautifully described, Captain Flinders saw a considerable number that glowed with the vivid colours of the rainbow :
" Where life in all her myriad mouldings plays,
Amid the beauty of the tropic blaze :
Enshrouded in the shadows of the past,
The mysterious workmen” to whose unseen labours the poet thus elegantly refers, are undoubtedly some of the most wonderful productions of the deep. Naturalists have traced the share they take in the formation of Coral and Corallines; it is also extremely probable, that many marine substances, supposed to be sea-plants, are in reality animal productions, formed by different kinds of Polypes for their abodes. Nor is it unlikely, that