The Aquarium (Gosse)/Chapter 7
Pl. IV.
P. H. Gosse. del. Hanhart Chromo lith.
THE PARASITIC ANEMONE &c.
CHAPTER VII
"I saw the peaceful main,
One molten mirror, one illumined plain,
Clear as the blue, sublime, o'erarching sky.
*****
A breeze sprang up, and with careering wing
Play'd like an unseen being on the water.
Slowly from slumber woke th' unwilling main,
Curling and murmuring, till the infant waves
Leap'd on his lap, and laugh'd in air and sunshine."
Montgomery.
A TRIP TO DURDLE-DOOR.
It was a sweet morning in July, when, intent on a trip down the Bay, we put the dredges on board the boat and made sail. A nice little air from the westward bellied out the red canvass, and we bowled away right before it. The craft in the harbour disappeared; the houses bordering the wide-spread esplanade, grew dimmer and dimmer behind us, till they were no longer distinguishable, and a slender line alone showed where they stood. This line at length faded into the general blue distant haze, that just said a belt of land was there, and that was all.
So memory of past events, as, on the rapid wings of time, we are ever borne farther and farther from them, towards the ocean of eternity, grows dim behind us. How much more faint I find the remembrance in detail of my summer at Ilfracombe, than it was a few months ago. My visit to Jamaica becomes every year more filled with hiatuses of recollection, and more and more reduces itself to a general hue; lovely and empurpled, indeed, it will ever be, but one in which it requires more and more effort to trace sequences and to separate adventures; while of early life how large a portion seems (perhaps only seems) consigned to absolute oblivion! Yet here and there, along the line of retrospective glance, there are points and prominences, which seem as if they could never die, occurrences which are, as it were, burnt-in on the memory, and which the haziness of approximate scenes and incidents serves only to place in bolder relief; just as an increase of distance often makes more conspicuous the mountain peaks, which the proximity of a multitude of minor objects concealed or obscured.
Suddenly the wind fails; ruffles up a little, then fails again; another little puff; but all in vain. The sea becomes as smooth as a table, as glassy as a mirror. There is a dancing, glimmering haze all round the horizon, which tells us it is all over with us; and the sun looking out of a sky unveiled by a cloud, pours down his ire upon our heads in the most ferocious manner possible;—and we a couple of leagues from home! I thought of the Ancient Mariner:—
"Down dropped the breeze, the sails dropped down;
Twas sad as sad could be;
And we did speak, only to break
The silence of the sea."
Nothing remained but to unstep the mast, and put out the oars. A curious perforated rock was not more than a mile or two distant, and we resolved to pull in for it, as I had heard of its singular appearance.
On approaching the shore a natural arch of imposing grandeur met the eye. The lofty cliffs of white chalk are interrupted for a little space by a huge promontory of black rock, cutting across the sandy beach, and projecting southward into the sea. The western angle of the mass sends off a spur which runs parallel with the shore, enclosing a snug little cove; and in the midst of this wall-like projection yawns a vast orifice, like an enormous arched gate-way leading into the little recess. This perforation is familiarly known as the Barn-door, or Durdle-door, and is one of the appointed places of resort to visitors. I had the advantage of seeing it in that silent solitude which is so congenial to the feelings when in the presence of some stupendous work of Divine power; no human soul being visible far or near, but the old lame and bald-headed shepherd, who had with much difficulty dragged himself down from the elevated downs above, and, having left his crutches on the sandy beach, was enjoying a bathe in the clear water. Even he disappeared, limping up a ravine in the precipice, before I could get ashore.
It was solemn to stand on the angular ledges beneath the arch, and gaze up at its magnificent span. The height of the vault and the depth of the water are sufficient to allow a vessel of considerable size to pass through, at high tide; but as it was now spring-tide and low water, our little boat could not safely thrid the bristling rocks that studded the passage, especially as there was some swell, which, though imperceptible out in the open sea, was heavy enough to bulge in the sides of a boat against these angular points and ribbed groins. We therefore rowed round the end of the wall into the little cove, and, making fast against the rock, stepped out as comfortably as if it had been a quay.
The rocky wall is about sixty yards in height, and nearly twice as long, from the angle of the promontory to its bold and almost perpendicular termination. Along the top, which appears nearly level, and is said to be a yard or two wide, it is possible to walk from the shore, and the view on each side from such a situation must present uncommon grandeur. Patches of samphire, thrift, and other cliff-loving plants, are seen adorning with verdure and gaiety the angles and dark fissures of the rock; and various species of sea fowl, among which are the guillemot, the auk, the puffin, the shag, and one or two kinds of gulls,—nestle on the shelves and ledges, and heighten by their cries the savage wildness of the scene.
Having satiated to some extent my appetite for the magnificent, I began to peer into the hollows and pools of the exposed rock beneath. From the over-shadowing darkness of the place I expected to make a good harvest; but though there were many likely cavities, and a good number of zoophytes and sea weeds, I found nothing with which I was not familiar before. I therefore set out to walk along the beach, beneath the chalk cliffs, to a somewhat similar projection of black rock, which blocks up the way about a mile off, at a place called Bat's Corner.
DURDLE DOOR.
The walk was fatiguing; the glare from the perpendicular precipice, an unbroken face of white chalk reflecting the rays of a July sun, was most oppressive to the eyes, soon inducing frontal headache; and the loose shingle alternating with looser sand afforded no firm hold for the sinking and sliding footsteps. My two lads ran before, chasing, with great glee, the young gulls, almost fledged, which had descended in some unintelligible manner, from their nest-ledges up the precipice, but were unable to fly. Cutting off their retreat to the water, the boys chased them till the poor things sought refuge in some corner of the cliff, where of course they were easily caught. They brought home two, nearly grown, which I believe they kept in their gardens for some time. They were probably the Lesser Black-backed Gull (Larus fuscus), though, as several species breed about these cliffs, which present little difference in their nesting plumage, I cannot be certain.
A heap of broken rocks, half exposed at lowest water, lies off the corner that terminates the beach. It is known to the fishermen by the name of the Cow and Calf. These rocks I wished to examine for Algæ, and found my search not fruitless. The species were growing from the broken fragments of fallen chalk in considerable abundance, and the specimens were particularly well-grown. Among them a pretty species was common, which I had not observed at Weymouth,—Chylocladia ovalis. I have compared the ramuli of C. articulata to bladders of red wine, set in chains; those of the present species are still more like such bladders, but more oval, and set in rows along the branches: the plant is also taller and more ramified.
But there were indications of a breeze springing up; clouds were forming over the land, and drifting to the southward, and "cats' paws" here and there were ruffling the silvery glaze of the sea into a deep blue. We got on board, and by the time we had pulled out a couple of hundred yards or so, down came a pleasant breeze, cool and fresh, from the north-west. The willing lads quickly stepped the mast, ran up the main-sail and jib, and, giving her a flowing sheet, put her before it; while the water began to ripple off under her quarter, with that rustling sound which a boatman loves to hear.
"Tοὶ δ' οτρύνοντος ἄκουσαν,
Ίστον δ' ἐιλάτινον κοίλης ἔντοσθε μεσόδμης
Στῆσαν ἀείραντες , κατὰ δὲ προτόνοισιν ἔδησαν,
Ἔλκον δ' ἰστία λευκὰ ἐϋστρέπτοισι βοεῦσιν.
Ἔπρησεν δ' ἄνεμος μέσον ἱστίν ὰμφὶ δε κῦμα
Στείρη πορφύρεον μεγάλ ἴαχε, νηὸς ἰούσης.
Ἤδ' ἔθεεν κατὰ χῦμα διαπρήσσουσα κέλευθον."
Od. β. 423
The dredges were quickly down; and while they were gathering their various contents, I put overboard my Medusa net, to see what the surface might produce on such a sweet summer day. No Medusæ were to be obtained, except one or two small specimens of Cydippe pomiformis, a brilliant little sphere of jelly, resembling the clearest glass, rowed along by ciliary paddles, set in eight rows, like the meridians of a globe. But the net came in loaded with tiny active creatures, which I saw, on putting some of them into a glass phial, to be the young of some Crab in one of the stages of its metamorphosis: not in that earliest state which is called Zoea, but that secondary condition known as Megalopa. Many of these minute animals I brought home, and placed in a vase, where they afforded me some entertainment.
These little creatures were about one fifth of an inch in length; they had assumed much of the form of a Crab, but the abdomen projected like a long slender tail behind, and was armed at the tip with fine radiating pencils of hairs. The eyes, which were very large, projected on each side, being set on thick footstalks; and as they were of a brilliant green hue, and very lustrous, they formed a conspicuous feature of the little animals. They manifested a sensibility to light correspondent to this development of the eyes. At night they congregated on that side of their glass prison, which was next the candle; and when I transferred the light to the opposite side, they immediately scuttled across, and crowded up as close to it as possible. They would follow the candle round and round the glass, shifting as it shifted, and stopping when it stopped. They were very nimble in swimming, generally keeping near the surface; but died off very fast: though the vessel was proportionally large, a few only out of some scores survived the first night. One or two, however, underwent the change into the Crab-form, which I was able to recognise as belonging to the genus Portunus.
I took an interesting fish in a somewhat unusual manner. Before the infant breeze had yet broken up the glassy surface of the sea, a small object was seen floating ahead, towards which we pulled. It proved to be a fine specimen of the Sordid Dragonet (Callionymus dracunculus); a fish which does not usually come to the surface, much less float there. It seemed stupified, making not the least attempt to escape, as we lifted it with the hand-net, and placed it in a pan of water. There, however, it seemed in no wise injured, but was as lively as so sluggish a fish usually is, playing on the bottom of the vessel. What could have caused it to lie in the burning rays of the sun, on the top of the sea?
The dredges yielded me a fair harvest of zoological varieties:—prettily painted Shrimps (Crangon); graceful Prawns of the genera Palæmon, Pandalus, and Hippolyte; the Tiny Cockle (Cardium eaiguum); two minute Tops (Trochus exiguus, and T. striatus); the porcellain-like Natice (N. Alderi and N. monilifera), remarkable for the enormous masses of white gelatinous flesh which they protrude when they crawl, investing and almost concealing the shell; a few Starfishes and Urchins; plenty of Ascidie and Botryllida; various Annelides;—Hermits and Spider-crabs by scores; several specimens of the beautiful Cloak Anemone (Adamsia maculata); and a few of that magnificent species, the Plumose Anemone (Actinia dianthus), as well as the Parasitic, the Daisy, and the Weymouth Anemones (A. parasitica, bellis, and clavata). Some of these I have already described; others I shall take occasion to allude to; I will here content myself with a notice of one of the most gorgeously clad of all the creatures that inhabit the deep,—the Sea Mouse.
It is not in its form that we must look for any peculiar elegance, for it is a flattened worm, of an oval outline bluntly pointed at each end;—nor in its general colour, for this is that of the pale brown sediment that water deposits. But it is in the clothing of long silky hair which covers each side, and which reflects the most brilliant and refulgent hues, equalling the splendours of the Humming-birds, or the Diamond-beetles. Hence Lamarck gave it the appellation of Halithea, or Sea-goddess; and Linnæus before him had conferred on it the name of the goddess of beauty, Aphrodite, the Greek title of Venus. The great master of Natural History thus expresses his admiration of this sea-worm. "The Aphrodite aculeata, reflecting the sun-beams from the depths of the sea, exhibits as vivid colours as the peacock itself, spreading its jewelled train."
In the Aquarium the Sea-mouse crawls restlessly to and fro, and round the margin of the bottom; once or twice I have seen it essay to burrow under the fine gravel, but generally it lives exposed. It is uninteresting in its manners, though the brilliance of its changing colours will always attract admiration. Perhaps it is most beautiful by candle-light, when red and orange reflections predominate; by day, pearly greens and blues prevail This difference is owing to the position of the light, and the angle at which it is reflected. Thus, if the eye glance along the bristles towards the light, which is reflected at an obtuse angle, the reflected rays will be lilac, passing into ultramarine; if the angle of reflection be a right-angle, the rays will be green; if the light be between the observer and the animal (not directly but obliquely, so as to make the angle of reflection more or less acute), the reflections will take yellow, orange, scarlet and crimson hues.
As it crawls, the Aphrodite usually elevates the tail, which is so folded together as to form a deep groove beneath. By watching this we see now and then ejected a stream of water, with considerable force. I found that the jet occurred once in twenty five seconds, with punctual regularity. This is a respiratory act; the grooved orifice through which the jet is poured is not the termination of the intestine, as we may at first suppose, but the exit of a capacious chamber which is external to the body, though concealed.
A very marvellous and quite unparallelled structure here comes into view. If we take a Sea-mouse into our hand, we see the whole breadth of the back occupied by a woolly substance, closely resembling felt, and formed by the interlacing of fine hairs. If we insert a pen-knife into the tail-groove and slit up this felt-like cover, we expose an ample cavity running the whole length of the animal, the floor of which is the true skin of the back, on which are set two rows of large overlapping plates, or membranous scales (elytra).
The dense tissue of interwoven hair resembling felt acts as a filter for the water to be respired, straining off the earthy particles held in it, which thus accumulate in its substance, and impart that peculiar dirty appearance which it possesses. The scales, according to Dr. Williams,[1] are periodically elevated and pressed. In the former action, the water permeates the felt, and fills the vacuum formed between them and the back. As soon as it is full, they collapse, and the filtered fluid, now deprived of its oxygen, is forcibly expelled at the anal groove. Well may the adoring Psalmist include among "the riches" of God; the "things creeping innumerable, both small and great beasts," wherewith "this great and wide sea" is filled![2]
PENNANT'S EBALIA.
A female of this quaint little Crab (Ebalia Pennantii) was obtained, the knobbed carapace of which carries a specimen of that curious pellucid Bryozoon, Alcyonidium gelatinosum. This is a fruit-like body about an inch in length, nearly cylindrical, with the tip rounded, and the base diminished to a footstalk springing from a minute point. The beautiful bell-like Polypes are projecting by hundreds from every part of the surface, distinctly perceptible even with the naked eye. Though this parasitic appendange springs from the very centre of the tuberculous cross on the back of the Crab, it projects forward over the head, a position which has relation to the burrowing habits of this liittle Crustacean.
The latter is inert, folding its legs on itself when touched, and remaining motionless for some time. It buries itself in the gravel, descending backwards: this is a somewhat slow process, suited to its usual phlegmatic habit. It brings its hindmost pairs of feet on each side together, then thrusting down their united points, opens and expands them, forcing apart the gravel: at the same moment the posterior part of the body is brought down into the hollow thus made, and the action of the feet is repeated. The process is continued until the hinder parts are covered, and the muzzle alone is visible, with the two claws. Thus it sits quite still, reminding one of a toad, the broad triangular pedipalps that fit so close, occasionally opening, like the folding doors of a tiny cabinet, and allowing the palpi to be thrust out to wipe the minute eyes. The face, when examined with a lens through the glass walls of the Aquarium, has a most funny expression, being singularly like that of an ancient man.
Like many marine animals, the Ebalia uses the hours of night as its chief season of activity. As long as the candles are in the room, it remains pretty still, but as soon as darkness reigns it sets out on its travels. Not indeed with the railway pace of some of its fellows, does our little ancient travel; he is but a "slow coach;" but he gropes about among the pebbles, and is usually found the next morning, buried at some distance from the point where the previous evening had left him. Fortunately his movements are easily traced; for the tall ventricose parasite which he carries on his back cannot easily be concealed; and this betrays the secret of his hiding-place.
I kept my little prisoner for five or six weeks; and he might have survived an indefinite time, but for the violence of a powerful neighbour. One morning I saw his shell and limbs broken to fragments, and emptied of all the soft parts. More than suspicion rested on the savage Violet Fiddler (Portunus puber), whose biography I shall presently record. The last occasion on which I had seen my little Ebalia alive was two days before, when I had routed him out of his burrow to show him to a visitor.
THE COMMON SOLDIER-CRAB.
The Soldiers (as indeed becomes their profession) are well known to be pugnacious and impudent; yet watchful and cautious. Indeed, their manners and disposition, no less than their appearance, bear the strongest resemblance to those of Spiders, a resemblance not peculiar to this genus, but more or less characteristic of all the Crabs. Two of them can scarcely approach each other without manifestations of hostility; each warily stretches out his long feet and feels the other, just as Spiders do, and strives to find an opportunity of seizing his opponent in some tender part with his own strong claws. Generally they are satisfied with the proofs afforded of mutual prowess, and each, finding the other armed at all points, retires; but, not unseldom, a regular passage of arms ensues, the claws are rapidly thrown about, widely gaping and threatening, and the combatants roll over and over in the tussle.
Sometimes, however, the aggressive spirit is more decided, more ferocious, more of the genuine Russian type. One in the Aquarium of the Zoological Gardens was seen to approach another, who tenanted a shell somewhat larger than his own, and, suddenly seizing his victim's front with his powerful claw, drag him like lightning from his house, into which the aggressor as swiftly inserted his own body, leaving the miserable sufferer struggling in the agonies of death.
The association which often exists between animals of different races and even of different classes, is always a curious phenomenon; and the motives which impel to the companionship, no less than the mode in which acquaintance is first formed, are most recondite. When this species (Pagurus bernhardus) inhabits the shells of the Whelk, it is quite common, though by no means universal, to find the spire of the shell occupied as the seat of that very fine Anemone, Act. parasitica, which rears its tall and stout form like a thick pillar, surmounted by its dense fringe of tentacles that wave, brush-like, with every vagrant movement of the Crab.
But I find that this association is not the only one that exists here. While I was feeding one of my Soldiers by giving him a fragment of cooked meat, which he having seized with one claw had transferred to the foot-jaws, and was munching, I saw protrude from between the body of the Crab and the Whelk- shell the head of a beautiful Worm, Nereis bilineata, which rapidly glided out round the Crab's right cheek, and, passing between the upper and lower foot-jaws, seized the morsel of food, and, retreating, forcibly dragged it from the Crab's very mouth. I beheld this with amazement, admiring that, though the Crab sought to recover his hold, he manifested not the least sign of anger at the actions of the Worm. I had afterwards many opportunities of seeing this scene enacted over again; indeed, on every occasion that I fed the Crab and watched its eating, the Worm appeared after a few moments, aware probably by the vibrations of its huge fellow-tenant's body, that feeding was going on, and not I think by any sense of smell, for a reason which I shall presently adduce. The mode and the place of the Worm's appearance were the same in every case, and it invariably glided to the Crab's mouth between the two left foot-jaws. I was surprised to observe what a cavern opened beneath the pointed head of the Nereis when it seized the morsel, and with what force comparatively large pieces were torn off and swallowed, and how firmly the throat-jaws held the piece when it would not yield. Occasionally it was dragged quite away from the Crab's jaws, and quickly carried into the recesses of the shell; sometimes in this case he put in one of his claws and recovered his morsel; at others he gave a sudden start at missing his grasp, which frightened the Worm and made it let go and retreat; but sometimes the latter made good his foray, and enjoyed his plunder in secret.
The worm is itself a striking and even handsome animal; and there is in its colours and their distribution,—two bright white lines running through the whole length on a light red ground,—a curious similarity to the colouring of the Crab.
I have reason to think that the partnership in question is by no means casual or exceptional, but ordinary if not constant. A second Whelk-shell in my Aquarium, surmounted also by a Parasitic Actinia, but which has been deserted by the Soldier, retains a Nereis as its tenant: and I know from experience as well as from the report of others, that this showy Worm is usually found, a co-occupant with the Soldier of old shells. The fishermen of Weymouth prize this Worm for bait more than any other; and are so well aware of its habits that they commonly break all Whelks containing Soldiers, in order to extract the Nereis which they know is within. Dr. Johnston in his description of N. bilineata (Ann. N. H. July, 1839) has alluded to their occurrence together.
Besides the interesting fact of this mutual friendship, we learn somewhat from the above observation of the rapacity and carnivorous habits of the genus Nereis, already inferred from their anatomical structure. That the senses of this Worm are not very acute I infer from the following experiment. I dropped a piece of meat into the mouth of the Whelk-shell that was tenanted only by a Nereis, and watched the result. After a time the Worm protruded, not apparently induced so to do by any expectation of food, and though its head was often brought almost into contact with the flesh, it was evidently unconscious of the proximity; for it took not the slightest notice of it, and allowed it to remain untouched all day.
The graphic description of the Soldier going about on the beach, turning over and examining shells, and now and then trying how they would fit his body,—has been so often quoted that we are apt to think it is a common sight, and may be witnessed by any stroller on a shelly beach. Yet I think the fact has been very seldom seen; and I judge so from my never having seen any other than the one well-known story, which, if I mistake not, was originally told by old Du Tertre of some American species. I have had the pleasure, however, of confirming its accuracy, at least in some points.
Looking at my Aquarium I saw that the Soldier was in a different Whelk-shell from his own. Both were surmounted, as I have said before, by the Parasitic Actinia, but a diversity in the colour of the tentacles rendered these distinguishable from each other at a glance. I shall call the Crab's own original Whelk, No. 1, and the other No. 2. My curiosity was excited of course, and I sat down to watch. The Crab kept fast hold of shell No. 1, by placing his walking feet within its aperture, all the time he was within No. 2. Presently he slipped out his plump posteriors from the new tenement, and in a moment popped back into his old one, which was indeed the larger of the two, and hobbled away.
The next day I saw the attempt renewed, and this time witnessed the procedure ab initio. The Soldier on his rambles blundered on a third Whelk-shell invested by the beautiful Adamsia, but untenanted. This he seized, rolled over, and turned about in all directions, feeling it in all parts, both within and without. The Adamsia he seemed not to like, and tried repeatedly to scrape it off the shell with his pincers, labouring hard at the work, though ineffectually: the rude operation appeared to produce little inconvenience to the soft and delicate, but tough-skinned Anemone, which withdrawing its tentacles, and contracting its body, offered a passive resistance to the persecutor. At length he was satisfied that the shell was much too small, and, relinquishing it, proceeded on his travels.
Presently he came to shell No. 2, that he had tried in vain yesterday; that essay, however, he had evidently forgotten, or at least did not recognise the shell; for he immediately began to turn it about, rolling it over and over with his sharp feet, twisting the Actinia most awry. He carefully examined the interior, feeling it all over with both claws, and trying every spot as far as he could reach; this examination he continued for perhaps five minutes, and then, as if satisfied, drewout his feet and made an essay to quit his own shell. It was apparent that the exposure of his soft person was considered somewhat dangerous, for he first felt with his antennæ in all directions around, vibrating them up and down, and partly coming out and retreating several times before he ventured. At length, however, out he popped, and into the new house as quickly, where he turned and settled himself comfortably. There was not much difference in dimensions between the shells, but, as I have said, what there was, was in favour of his original dwelling.
He remained in his new quarters for ten minutes or more, moving about a little, but never for an instant letting go his old house, on which he pertinaciously kept his feet, occasionally putting in his pincers to feel the interior. At length he decided that, inconvenient as it was, it was better than the new one; and therefore he returned to it, as he had done the previous day, and relinquished the attempt.
The day following he repeated the same process of temporary exchange, walking about for a considerable time with his new abode, and yet at length resuming the old one.
On a subsequent occason I saw another individual of the same species reduced to the condition of a "houseless wanderer". The whelk-shell which it inhabited had been laid hold of by the sucking feet of a Sea Urchin (Echinus miliaris), the Soldier having rested in unconscious proximity to this adhesive subject. The rest of the Urchin's feet were firmly moored to the solid rock, so that when the Crab attempted to walk, he found his home-shell immoveable. What was to be done? He was probably hungry after his repose, and food must be sought. After vainly dragging for a few minutes, he chose the alternative of exposure, let go his posterior hold, slipped from the shell, and wandered naked. Half a day he roamed in this defenceless state, till, meeting with a large whelk-shell empty, he gladly popped in, and, though the tenement was inconveniently ample, kept possession, wisely judging that inconvenience was preferable to danger.
It is a doubtful point whether the Soldier is a murderer and free-booter, like Ahab in Naboth's vineyard, slaying before he takes possession, whenever he happens to fancy a tenanted shell, or whether he merely makes free with a house that he finds unoccupied. Wishing to settle the point, I procured a living Whelk of about the size to suit the Crab's necessity, and put it into the tank, when the latter was in the state of uneasiness described above. But, though they were thus thrown into association for several days, the Soldier never made the least assault upon the living Mollusk, nor attempted to take his shell.
After the proceeding observations were written, my esteemed relative James A. Salter, Esq. mentioned in conversation that he had witnessed the process of the Soldier's "moving house". At my request he has favoured me with the following particulars, which, while they agree with my own observations in essential points, superadd some interesting details.
"I have many times found Hermit-crabs out of their Shells in the mingled mass of a dredge-haul, and on three occasions have watched the method in which the houseless creature domiciliates himself. These were the only occasions on which I endeavoured to observe the operation: they always seem willing enough to exhibit their housing performance.
My plan of observation was simply this:—I put a naked crab into a large glass jar of sea water with one shell, the latter of size about proportioned to the former; and then I contemplated. In each case the crab proceeded in the same way.
Appearing to see the shell in the distance the animal crawled up to it for the purpose of seeing if the house were to let; and this circumstance he discovered not by sight, but touch. Upon reaching the shell he hooked two of his legs into its open mouth, and thrusting them as far down into its cavity as possible, commenced scrambling round the edge: he was evidently probing to discover if there were already an inhabitant. In each case the crab pursued this probing operation in the same direction—commencing on the projecting side of the shell, and ending on the receding side. Having performed this process once round, he instantly, in the twinkling of an eye, erected straight his tail, and whisked himself over the smooth lip of the shell into its tube with a rapid adroitness that was perfectly marvellous. And then in his new contrasted position he looked so funny—such at-homeishness there was in it; he was so different from the poor houseless vagabond with a drivelling tail, that one had seen miserably crawling about a moment before: he looked right up in your face and said, as plainly as looks can speak, 'How d'ye do? here I am, quite at home already. I never saw it without laughing.
THE COMMON PRAWN, AND THE BULLHEAD PRAWN.
The Prawns are particularly pleasing inhabitants of the Aquarium. There is a certain lightness in the slender filiform appendages of the head, which are continually thrown into the most graceful curves, that resembles in character "the light tracery of ropes and spars" so much admired in a trimly rigged ship. Their bodies are so pellucid that a lady who was this moment looking at the Tank compared them to ghosts, and their smooth gliding movements aid the similitude. The beautiful colours which adorn them I have described elsewhere, and shall merely here say that the fine contrasts of the black-margined lines of pale yellow with the pellucid grey of the ground, show well as the animals rest on the dark stones. The two species (P. serratus and P. squilla) are so closely alike in their colours and in the distribution of these, that it is only by minute examination and comparison that we can determine what is characteristic of each. The most obvious distinction is, that in the former the outer tail-plate has a yellow line, the intermediate one no spot or rarely a minute speck; the middle plate two parallel specks also minute. In P. squilla each plate has a roundish or squarish spot of yellow, all equal in size, and forming an angular band of spots. The distinctions drawn from the form and dentition of the rostrum, and the gibbous carapace of P. squilla, I need not speak of particularly, as these are sufficiently appreciable in cabinet specimens.
When viewed with a candle the eyes of the Prawn reflect the light with a glare exactly like that seen in a cat's eyes under similar circumstances. The light, in the case of the Prawn, is seen only when the candle is held between the beholder and the insect, and becomes brighter and larger the more nearly the flame of the candle is brought to the line which unites the observer's eyes and the object. It might seem as if nothing could possibly be discerned when the flame is absolutely in this line, but it is not so; both eyes being open, the line of vision of each eye passes on one side of the candle, and we discern the two eyes of the Prawn, like two little globes of fire.
In the case of the cat the phenomenon is said to be produced by the choroid coat at the bottom of the eye (tapetum lucidum), reflecting from its polished metal-like surface the entering rays, and converging them by its concavity, as if from a concave mirror. This is simple and perfectly intelligible; but I do not see how a similar effect is produced in the compound eyes of the Crustacea, each of which is composed of a great number of conical lenses with apices inward. What is there in this structure that can represent a concave mirror? Yet no one can look at the sight I am speaking of, without feeling certain that the optical process is one of concave reflection and convergence of the rays; and that the reflecting surface is in the interior of the globose compound eye. The reflection is seen whatever part of the eye is opposite the light, (provided it be facetted of course) but is most full direct in front, where no unfacetted portion can be seen. Yet it certainly has no connexion whatever with reflection from the exterior surface, as might be suggested by any one who has not actually seen it: the effect of this would be a minute point of light, very different from this broad round gleam.
The different species of Pagurus, and Crabs, as Portunus, exhibit the same phenomenon, but in a lower degree; the disk of light being smaller and of less brilliance; though their eyes are larger. I have seen the same appearance in the eyes of Moths and other nocturnal insects; so that doubtless it is dependent on the common structure of facetted compound eyes.
It is pretty to see the Prawn fed. When a morsel of food is dropped through the water near its head, the excessively long antennæ, (especially the long filaments of the superior pair, which are carried perpendicularly upwards) seem principally to take cognizance of its presence and of its qualities. The eyes, though evidently alert, are I think less trusted. As the morsel comes within reach, the second feet, the principal organs of prehension, are stretched out, with the two fingers (pincers) widely extended; these seize it with the most easy action possible, and in a moment thrust it towards the mouth.
CLEANLINESS.
Many contemplative minds have been exercised on the immense amount of energy and time that are expended in the mere procuring of food and clothing; and the pious have bowed to the necessity as part of the curse under which the earth still groans on account of sin. "In the sweat of thy face shalt thou eat bread" was the righteous sentence on fallen man; and we know assuredly that if innocence had remained, other clothing would have been un-needed.
But possibly it may not have struck every one that almost as much of time and labour are consumed in cleansing away impurities. Our bodies, our garments, our furniture, our houses, our streets, are perpetually being cleaned: it is clean, clean, clean,-wash, scrub, scour, brush, sweep,-from morning to night, from week to week, from year to year, a constant unremitting war with dirt; a war hopeless because endless, a war with an enemy that may be kept in check, but can never be conquered. No sooner by herculean efforts have we made a successful onslaught on the foe, and apparently subdued him so that he cannot shew his face again, and begin to sit down in complacency, than lo! we descry his unsightly sappers and miners retaking all the points we thought we had secured, and we exclaim, in disappointment and despair;
"The creature's at his dirty work again!"
I incline to think that this necessity is as much a judicial sentence as the other; that it also is part of the curse. It is true we may trace it to the laws of matter; to the excretions of living beings, the natural course of decomposition in organic substances, the abrasion of inorganic surfaces by friction, the laws of motion, of gravitation, and the like. I know that all this may be said, and said truly; and yet I doubt much if this perpetual round of strife with dirt, that makes the poet's lamentable ditty,—
"There is nae luck aboot the hoose
Upon a washin' day,"
applicable to all the world and co-extensive with all time, would have been our lot, if we had maintained a Paradisiacal condition of existence.
Be it so! judgment in neither case is unmingled with mercy. It is not an unmitigated curse under which Creation groans. A Father's hand is manifest in the wisdom and love, which has made the promounced and inevitable sentence to be a corrective discipline, and not a vindictive punishment. What crimes have been prevented, what proficiency in iniquity cut short by the necessity of labour for the support of life! And in like manner tens of thousands are daily kept out of idleness, and its concomitant temptations, by the incessant demands of cleanliness upon toil. The condition of existence being what it is, a fallen condition, a state in which a proclivity to sin is the universal rule, how merciful is the appointment of a discipline which should directly minister blessing to the mass of mankind in several ways! Preventively, by limiting our opportunities of evil; temporally by giving support, directly or indirectly, to myriads of persons; and spiritually, by reminding us of an inward uncleanness, which must be effectually purged away, before we can become inhabitants of that city of light and bliss, into which shall enter "nothing that defileth!"
If this is a correct aspect of the subject, it was natural that the inferior creatures who fell federally in their lord and head, should share in the consequences of his sad lapse. Hence we find not only that the procuring of food occupies a large portion of the time and energy of the brute animals, but also that of what remains much is devoted to operations of cleanliness, personal and local. In all probability both of these occupations are to them actually pleasant, instead of burdensome; their part of the punishment (as I have elsewhere remarked) is, in many respects, indignity rather than suffering, though they have enough of the latter too. Every one has seen how much of her leisure is occupied by a cat in cleansing herself and her offspring, and the zest with which she goes through her task indicates that it is not unpleasing. Other animals perform analogous operations, varied, however, so much in the details of their purposes, modes and implements, that I am persuaded an interesting treatise might be written exclusively on animal cleanliness.
I am not going to write such a treatise, but merely to describe an example that I have noticed tenants of my Aquarium. I have before said that the second pair of feet are used by the Prawn (Palæmon) as his principal organs of prehension; and this might have been inferred from their superior length and stoutness, particularly the size of the pincers or didactyle hands. On cursory observation you are puzzled to know what is the use of the slender first pair, which are also furnished with didactyle hands, but very diminutive and feeble. See the Prawn, however, washing himself after dinner, or at any other spare moment, for he is careful to maintain his polished coat of mail most scrupulously clean. You will then see that the front feet are cleansing organs. They are beset with hairs which stand out at right angles to the length of the limb, radiating in all directions, like the bristles of a bottle-brush. You will not see them to advantage, it is true, in dried specimens; but in a living state, or even when preserved in spirits, they are conspicuous enough under a lens. These are the Prawn's washing brushes, especially applied to the cleansing of the under surface of the thorax and abdomen. When engaged in this operation, the animal commonly throws in the tail under the body, in that manner which we see assumed in the pink specimens that are brought to table, which is not, however, the ordinary posture of life, the body being nearly straight. Then he brings his forefeet to bear on the belly, thrusting the bottle-brushes to and fro, and into every angle and hollow with zealous industry, withdrawing them now and then, and clearing them of dirt by passing them between the foot-jaws. The reason of the inbending of the tail is manifest; the brushes could not else reach the hinder joints of the body, and still less the swimming plates; but by this means every part is brought within easy reach. Sometimes the brushes are inserted between the edge of the carapace and the body, and are thrust to and fro, penetrating to an astonishing distance, as may be distinctly seen through the transparent integument. Ever and anon the tiny forceps of the hand are employed to seize and pull off any fragment of extraneous matter which clings to the skin too firmly to be removed by brushing; it is plucked off, and thrown away, clear of the body and limbs. The long antennæ and all the other limbs, are cleaned by means of the foot-jaws principally.
THE SERPULA.
There is scarcely any object more familiar to the eye of one accustomed to dredge, or to pore about the water's edge at extreme low tide, than the tubes of stony or shelly substance which are found adhering, in various contortions and aggregations, to almost every stationary object that is habitually submersed. The undersides of every ledge, of every boulder, and almost every pebble, are studded with these twisting, creeping tubes, which seem to contend with the crowding Acorn-barnacles (Balanus) for the possession of every inch of space within their domain. Those that occur within tide-marks are usually of a small species, with the tube strongly carinated, and somewhat three-sided, and the exposed part of the animal banded with blueish-grey. But in deep water they are much finer, and more brilliantly coloured. I believe the former is S. triquetra, the latter S. contortuplicata; but the species of this tribe have yet to be disentangled from the confusion of closet nomenclature. It is of the deep-water species that I would speak; not the rarer solitary kind (S. tubularia), that adheres to the stone or shell by only a small portion of its tip, and rears the remainder of its tube in pillar-like erectness to the height of half a foot or more;—but of that most abundant one, which every haul of the dredge raises, on old shells, broken pottery, fragments of bottles, &c. grouped in intricately contorted and intertwisted masses, which adhere for the greater part of their length, and are free only at or near the anterior extremity.
The tubes of fine specimens are about one fourth of an inch in diameter, cylindrical, with the mouth slightly expanded. The successive stages of growth may be traced by these expansions, for the addition is evidently made, not from the expanded edge, but from a little way within, so that the general diameter of the tube is preserved, while these trumpet-lips project at irregular distances, in a foliated manner, like the bases of sheathing leaves. You would probably look with little interest on these clumps of dirty-white, rough tubes, on seeing them come up in the dredge, but in an Aquarium few objects are more attractive. As soon as the tenants of these pipes begin to feel themselves at home, they cautiously protrude. The first thing you see is what looks like a scarlet cork fitted into the mouth of the tube, as if into the neck of a bottle; by gradual steps, this is pushed a little, and a little, farther out, until at length a brilliant array of fans of the same gorgeous hue protrudes, and expands into a sort of oval funnel, defective at one side, and with the opposite margin bent inward in a sinuous form.
Take your pocket lens now, and examine the structure of these brilliant organs in detail. Presto! on the slightest movement of your hand towards him, he is gone! He has retreated like a lightning-flash into his tube. But did you notice how cleverly, as he went, he shut the door after him? A most marvellous contrivance is here. Watch it as it again carefully protrudes. There is a solid organ exactly conical, seated at the end of a long flexible stem, which forms the stopper; it is one of a pair of tentacles, but as only one could be of any service as a stopper, one only is developed; the other being minute. This stopper is very beautiful; it is always richly coloured, usually orange, or vermilion, sometimes varied with pure white: its flat extremity or top is made up of ridges, which run from the centre to the circumference, where they project in tiny teeth of the most exact regularity. The fan-like expansions are formed of radiating filaments, also very brilliant in hue, which are the breathing organs, separating oxygen from the currents of water which play along their ciliated surfaces.
There is no distinct head in these animals, but the organs I have described are protected by a sort of projecting mantle or hood, beneath which is the orifice of the stomach. Eyes it seems to have, and most sharp ones; for, as we saw, the animal is peculiarly sensitive to the approach of any object, even though this be on the outside of a glass tank, at the bottom of whose interior it is expanded. Yet I have searched in vain for any distinct organs of vision.
The mechanism by which the Serpula projects its body from its shelly tube, and by which it withdraws on alarm with such inconceivable rapidity, is wondrously curious. I will describe each of these in turn. Behind the head, (or what for convenience may be so termed) the sides of the body are cut into nipple-like feet, about seven pairs in all, which are perforated, and carry so many bundles of fine, elastic, horny bristles, like the hairs of a camel's-hair pencil, each pencil carrying from twenty to thirty bristles. By means of suitable muscles, the pencils are pushed out to their full length, or withdrawn so as to be wholly sheathed in the foot.
Now let us look at the structure of these bristles. A few are simple hairs, but the majority are instruments of elaborate workmanship, though high powers of the microscope are needful to display them well. Each bristle consists of a transparent, yellow, horny shaft, the extremity of which dilates into a slightly enlarged knob. This is cleft into four points, three of which are minute, but the fourth is developed into a long, slightly divergent, highly elastic, tapering, and finely pointed spear.
These organs come into operation when the animal would extrude its body from the mouth of its tube. Their action is manifestly that of pushing against the walls of the interior, which on close examination are seen to be lined with a delicate membrane, exuded from the animal's skin. The opposite feet of one segment protrude the pencils of bristles, one on each side, the acute points of which penetrate and catch in the lining membrane; the segments behind this are now drawn up close, and extend their bristles; these catch in like manner; then an elongating movement takes place; the pencils of the anterior segments being now retracted, they yield to the movement and are pushed forward, while the others are held firm by the resistance of their holding bristles; thus gradually the foreparts of the animal are exposed.
But this gradual process would ill suit the necessity of a creature so sensitive to alarm, when it wishes to retreat. We have already seen how, with the fleetness of a thought, its beautiful crown of scarlet plumes disappears within its stony fastness; let us now look at the apparatus which effects this movement.
If we look at a Serpula recently dead,—which we may readily do, since it is the habit of most tubicolous Annelida to come out to die,—we shall find, with a lens, a pale yellow line running along the upper surface of each foot, transversely to the length of the body. This is the border of an exessively delicate membrane, and on placing it under a high power (say 300 diameters) we are astonished at the elaborate provision here made for prehension. This yellow line, which cannot be appreciated by the unassisted eye, is a muscular ribbon, on which stand up edgewise a multitude of what I will call combs, or rather sub-triangular plates. The edge of each plate is cut very regularly into six teeth, which curve in one direction, and one other curved so as to face these. The combs stand side by side, parallel to each other, along the whole length of the ribbon, and there are muscular fibres seen affixed to the smaller end of every plate, which doubtless give it independent motion. I counted 136 plates on one ribbon; there are two ribbons on each thoracic segment, and there are seven such segments:—hence we may compute the total number of prehensile comb-like plates to be about one thousand nine hundred, each of which is wielded by muscles at the will of the animal; while, as each plate carries seven teeth, there are between thirteen and fourteen thousand teeth hooked into the lining membrane of the cell, when the animal chooses to descend. No wonder, with so many muscles wielding so many grappling hooks, that the retreat is so rapidly effected!
A group of Serpule of the species which I have been describing, is represented in Plate V.