As I have said, it appeared to me delicious. Was it the Provençal dish, the savoury bouillabaise, which contributed to my appreciation of the humble sea-urchin of the Mediterranean? Was not the marvellous view which I enjoyed from the heights of my empyreum of glass the indirect cause of it? This is a tender and charming problem which I love to leave floating in the clouds, half evanescent, of my youthful recollections.
Holothuria.
The ignorant, like you and I, call the Holothuria the Cornechou, or Sea-cucumber, and perhaps, for two reasons, they are not far wrong. The term sea-cucumber expresses with wonderful exactness the shape of the animal, and its habitation, the sea; and, again, it would puzzle the most learned to explain the word Holothuria. The body of this strange creature presents the form of an elongated and worm-like cylinder; its dimensions are so variable that, while some species are only an inch or two in length, others attain thirty and even forty. In general, the skin of the Holothuria is thick and leathery; it includes muscles, and is armed occasionally with small projecting hooks or fangs, which enable the creature to hang for a few seconds on to foreign bodies. From this coriaceous envelope issue tentacular feet analogous to those described in the sea-urchin and sea-star.
When we open a Holothuria we find nearly the whole internal cavity occupied with little white tubes. We know that the fabulous cucumber spoken of in the "Arabian Nights" was stuffed with pearls by the talking-bird. With our poor animal this, alas! is not so. These are no pearls, but simple prosaical tubes containing the ova. The mouth opens at the extremity of the body; it forms a sort of funnel, and is surrounded, as by a glory, with an elegant circle of tentacula. In the living animal, when it feels itself in security, these tentacles expand themselves like the corolla of a flower. When the fisherman seizes a Holothuria in the water this crown of tentacles ceases to appear, for the animal has the power of withdrawing it quite suddenly, and now it resembles nothing so much as a common leech. If, however, it is preserved in fresh sea-water and left in peace—if we treat it, in short, with the regard due to its elegant crown of tentacula—this elegant ornament will be expanded in all its glory. Immediately below the mouth is a muscular pharynx, which is contained in a long intestine, with many convolutions, which terminate in the posterior part of the body in an orifice whence is thrown from time to time a little jet of water. The terminal portion of the intestinal canal in these animals is enlarged, introducing us to a system of numerous tubes which branch off into the visceral cavity, receiving the water from without while breathing by its posterior extremity; the animal can at will fill this reservoir or eject the water, and it is by these alternate movements of aspiration and its reverse that it renews the oxygen necessary for respiration. The circulation appears to form a complete circle, there being no heart or central agent; but a ring round the gullet, from which issue five principal nervous chords, represents the nervous system.
The Holothurias are of separate sexes, and they differ from the sea-urchins and asterias in this: that their larvæ are converted bodily into a young Holothuria without losing their organs. The bodies of certain species are lubricated by an acrid and corrosive liquid: thus H. oceania, described by Lesson, which is about forty inches in length, secretes at the surface of its body an irritating fluid, which produces an intolerable itching in the finger which touches it. Nor can the inhabitants of the South Sea Islands look at it without loathing. Fig. 119 represents H. lutea, or the Stychopus luteus of Brandt, who describes as its distinctive character three rows of tentacular feet on the ventral surface.
Fig. 119. Holothuria lutea (Quoy and Gaimard).
We have spoken of the strange suicidal tendency of the sea-stars: the Holothuria exhibits the same phenomena, but, having no brittle envelope like the asterias, it cannot break itself into bits in the presence of its disconcerted enemy; but kills itself in this manner: having some cause of grief and trouble—such, for instance, as the attack of an enemy or the pursuit of some fisherman—by a sudden and unexpected movement it ejects its teeth, its stomach, its digestive apparatus, and reduces itself to a simple empty membranous sac, with an unfurnished mouth; and, as a singular fact, this empty sac still shrinks and contracts in the hand which grasps it. It must be admitted that this is a strange mode of evading its enemies: the soldier rarely throws his arms away in the moment of danger! But the Holothurias possess a wonderful recuperative power also; and it is probably quite conscious, when it thus empties itself to disappoint its pursuer, that it can promptly replace the organs which it has voluntarily parted with.
Dr. Johnston relates that he had forgotten for some days to supply a Holothuria with a change of water. The creature, in consequence, ejected its tentacles, its buccal apparatus, digestive tubes, and a portion of its ovaries. Still it was not dead, but was sensible to the least movement, and lived to reproduce all its organs anew.
Not only do the Holothurias eject their organs and afterwards renew them, but they divide themselves spontaneously into two portions. Their two extremities are first enlarged; then their middle parts gradually become straight, like a thread: finally, this thread breaks, and each separate part of the animal becomes a perfect Holothuria. It has been cut into two pieces, and each of these species becomes a new being.