The Aquarium (Gosse)/Chapter 10
CHAPTER X.
THE TRUMPET LUCERNARIA.
The summer was over, but I still lingered at Weymouth. Spring-tides came and went with tantalizing regularity; but, though the sea receded far below the lowest level reached in summer, it was almost unavailable to me. Day after day I used to go down and look upon the ledges, but fierce autumnal gales blew with characteristic violence and pertinacity, and huge seas rolled in, sweeping over the flats, shooting up in forcible jets from the fissures, and laying bare for a moment large tracts of inviting sea-weeds, only to cover them the next a fathom deep.
In a brief interval of gentleness, however, I found an animal which had long been an object of desire to me, a normal form of the genus Lucernaria. The small, aberrant, vase-like species, L. cyathiformis, I had taken already; but I wished to see the more elegant sorts, which resemble in figure the trumpet-shaped flower of a Convolvulus, representations of which by the pencil of Mrs. Johnston I had been in the habit of admiring, in her husband's admirable "History of British Zoophytes."
It was on the 3rd of October, that I detached, at that sort of little natural pier that I have described under the Nothe cliffs, a frond of Fucus serratus with a bushy tuft of Rhodomela subfusca growing parasitically on it. To one of the branchlets of the latter plant a little mass of jelly was adhering, which, on my dropping the branch into a phial of water, presently expanded, and I had the pleasure of seeing the bell-like form of Lucernaria auricula. It was a very young specimen, not much more than one eighth of an inch in height; but I had got a clue to the search, and I subsequently obtained through the month of October many more. In spite of the gales and seas, I managed to drag up a good deal of the Fucus, which is hereabout profusely fringed with Rhodomela, and also with Ceramium rubrum; and on these, as also occasionally on the Fucus itself, and once or twice on Padina, I found the Lucernariæ.
My mode of examination was as follows. Collecting a basketful of the tufts at random, I brought them home; then one by one I waved them to and fro, in the Tank of water, between my eye and the light, whereby the animals became distinctly discernible, and were easily detached. Sometimes four or five were scattered over one tuft of the parasitic plant, and it was rare to find a Rhodomela of any size, without one at least.
The specimens were evidently the young of the season; many were no larger than I have named; but some were as much as one-third of an inch in diameter. They were very beautiful, closely resembling a bell- or trumpet-mouthed monopetalous flower, with a short flexible footstalk, and a small, expanded, sucking disk at the base. The substance was clear, transparent, gelatinous; the flower-like expansion thin and filmy, with the margin projecting into eight equidistant points. From each of these points radiated about twenty slender tentacular threads, bearing at their extremities orange or yellow globules. The ovaries radiated in eight irregular bands from the centre of the flower to the marginal points, and from the centre itself projected a little, protrusile, four-cleft mouth; closely like the peduncle of a Thaumantias. Indeed I was strongly struck with the resemblance which the creature bore to a small Medusa, and I consider it as a link that connects the normal Actiniæ with the Acalephæ.
In some specimens there were eight little oval warts which hung from the outside of the margin, placed midway between the angles or points. Montagu has made these warts the distinctive character of this species; but I think they are not to be depended on; for many of my specimens, not at all to be distinguished from these in form, colour or habit, were destitute of the least trace of the warts. It is possible that it may be a distinction of sex.
The specimens were very difficult to preserve alive. The beautiful groups of globe-headed threads soon contracted and agglutinated into shapeless masses, the hold of the foot loosened, and the animal dropped helpless to the bottom, and decayed. Indeed, I found that the hold was very readily let go, even in health; the little animal travels quickly, causing itself to adhere to any substance, either by the contact of the tentacles, of the marginal warts, or of the foot-disk.
From what O. Fabricius says of the food of this species,—"vescitur oniscis,"—I presented to one a little Gammarus locusta; the Lucernaria strove to take in the prey with its mobile mouth, and succeeded in partially embracing it, holding it for several hours, after which it dropped it. The shrimp was early rendered powerless.
In colour these delicate creatures vary much. The expanded membrane is usually colourless; but the mouth, the ovaries, the edges of the disk, and the foot display colour. This may be grass-green, olive, drab, whitish, or various shades of rose-pink. The warts are commonly whitish, and the tentacle-globules pale orange yellow. In some specimens, opaque-white specks were scattered over the disk, which in others were absolutely wanting. The nature of these I cannot conjecture.
In February of the present year (1854) Mr. Thompson of Weymouth was so kind as to send me up several specimens of what I take to be a distinct species, L. campanulata. It is less elegant, more cup- or bell-shaped, with scarcely any perceptible stalk. These specimens were about an inch in height, more dense in texture, of a dark dull green hue.
My friend has favoured me with the following notice of the habits of this species. "The Lucernariœ I find as fellows:—at extreme low water, beds of sea-grass (Zostera marina) are exposed; on some of these, little pools, four or five feet across, and eighteen inches deep, are formed, the matted roots of the Zostera having been washed away. The bottom of the pools is of clear sand, with innumerable broken tubes of a species of Sabella [Terebella?] and a few Pagurus bernhardus, all small specimens; also Venus striatula and Mactra stultorum. On the surface of these little lakes and round the edges, float the leaves of the Zostera which grow nearest the margin; and attached to these leaves on their under sides, with the mouth and tentacles downwards, rests the Lucernaria on the watch for prey; at times in a state of rest, at others in constant motion. The heads of the tentacles possess great power of adhesion, and I expect you will find the filaments or threads highly developed."
The accompanying plate represents two specimens of Lucernaria auricula attached to a pendent thread of sea-weed. In the foreground is that fine bivalve (Pectunculus pilosus), which is taken in deep water in this Bay; its summit is covered with the common Acorn-shell (Balanus balanoides); on which rests the Scarlet-lined Æsop-prawn (Pandalus annulicornis). Behind this spring two fronds of the Ladies' tresses (Laminaria phyllitis.) From the rock above the Lucernariæ is growing a bushy tuft of a coarse but curious Alga (Ceramium echionotum); and below is seen a plant of exquisite structure, one of the most simple, but one of the most lovely of sea-weeds, the Bryopsis plumosa.
Pl. VI.
P. H. Gosse. del. Hanhart Chromo lith.
THE ÆSOP PRAWN &c.
A LAST LOOK AT WEYMOUTH.
In this changing state, the brightest, like
"the darkest day,
Live till to-morrow, will have passed away;"
—the summer, only too swiftly, passes into autumn, and autumn quickly merges into gloomy winter. The sea-side has few charms in December; reluctlantly, we took our last walk upon the now bleak and spongy Nothe, our last stroll along the gusty and deserted Esplanade, and our last look at Weymouth. This, however, was a charming one. Just half-way between Weymouth and Dorchester, the hills, which rise gradually on each side, attain their greatest elevation, and the high-road passes over the summit of the ridge. Here we made the carriage halt, and for ten minutes
"cast one longing lingering look behind,"
on a widely-expanded panorama of the scenes with which we had been so familiar. The sun and sky were all that could be wished; the air more autumnal than wintry; and, as we gazed on the town and harbour, about four miles distant, the long promontory of the Nothe, the calm silvery Bay, the huge mass of Portland, like a sleeping lion, and the boundless expanse of open sea beyond, we could not help feeling that this was by far the finest prospect we had seen in Dorsetshire.
But even in London, thanks to the Aquarium, the same pleasant studies can be prosecuted that had occupied me on the coast; and thus, by means of a few specimens that I brought up with me, and by the aid of contributions forwarded to me by the kind courtesy of friends, I have yet a few more notes to add to the zoological portion of this volume. The chief of these collections were sent me by Mr. William Thompson from Weymouth, and by the Rev. C. Kingsley from Torquay; and to these gentlemen, as well as to other friends who have aided me, I beg thus to express my grateful obligations.
THE SPINOUS COCKLES.
Among a number of animals of great interest kindly sent to me in January from the vicinity of Torquay, by the Rev. C. Kingsley, were a posse of Cockles; not the plebeian sort that boys with stentorian lungs cry about the streets of sea-port towns at "twopence a quart," but those giants, Cardium aculeatum and C. tuberculatum, the real aristocracy of the Cockle kind. The favour of the kind donor was the greater, as the sands of Livermead and Paignton, whence these were procured, are almost the only British locality for the species, especially the latter, which is among the rarest as well as finest of our native bivalves.
They looked healthy when turned out of the jar, though they had performed their journey up, in that bitter, almost Arctic, weather that we had at the beginning of January; and, under the excitement of the genial atmosphere of the parlour, they presently grew quite frisky. Many persons are aware that the Common Cockle can perform gymnastic feats of no mean celebrity, but the evolutions of Signor Tuberculato are worth seeing. Some of the troupe I had put into a pan of sea-water, others I had turned out into a dish dry, as knowing that an occasional exposure to the air is a contingency that they are not unused to. By and by, as we were quietly reading, our attention was attracted to the table where the dish was placed, by a rattling uproar, as if flint stones were rolling one over the other about the dish. "Oh! Look at the Cockles!" was the exclamation; and they were indeed displaying their agility, and their beauty too, in fine style. The valves of the largest were gaping to the extent of three quarters of an inch; but the intermediate space was filled up by the spongy-looking, fleshy mantle, of a semi-pellucid orange hue. At one end protruded the siphons, two thick, short tubes, soldered as it were into one, and enveloped on all sides in a shaggy fringe of cirri or tentacles. The circular orifices of these tubes,—small holes perfectly round, with a white border,—had a curious appearance as we looked at the heart-shaped end of the valves. The discharging orifice, however, was but rarely visible; being usually closed, while the other remained constantly open. But these things were what we afterwards saw: for some time we could look at nothing but the magnificent foot, and the curious manner in which it was used.
The two lips of the mantle suddenly separate, and, gaping widely all along the front, recede nearly to the valves; while, at the same moment, a huge organ is thrust out somewhat like a tongue, nearly cylindrical, but a little flattened, and tapering to a point. Its surface is smooth and brilliantly glossy; and its colour a fine rich scarlet, approaching to orange; but a better idea of it than can be conveyed by any description will be obtained by supposing it to be made of polished carnelian. This beautiful and versatile foot is suddenly thrust out sideways, to the distance of four inches from the shell. Then, its point being curved backwards, the animal pushes it strongly against any opposing object, by the resistance of which the whole animal, shell and all, makes a considerable step forwards. If the Cockle were on its native sands, the leaps thus made would, doubtless, be more precise in their direction, and much more effective; but, cooped up with its fellows in a deep dish, all these herculean efforts availed only to knock the massive shells against the sides, or roll them irregularly over each other.
It was curious to notice the extent to which the interior of the Cockle was revealed, when the mouth gaped, and the foot was thrust out. By the aid of a candle we could see the interior surfaces of both valves, as it seemed, almost to the very backs. I say, as it seemed, for so thin is the mantle where it lines the shell, and so closely does it adhere to it, that every character of the valves, whether as regards colour or irregularity of surface, was distinctly visible; and thus we were able to distinguish the species, not only by their external marks, but by one character drawn from the interior;—the ribs in tuberculatum extending only half-way across the valves, while in aculeatum they reach back to the beaks.
The former is much the finer species; the valves are more globose, and of a warmer colour; those that I have are even more spinous. The mantle is of a rich deep orange, with elevated ribs, corresponding to those of the valves, of a yellow hue. These ribs of the mantle are visible in aculeatum also, but in tuberculatum, they are much more strongly marked, both in form and colour. The siphons display the same orange hue as the mantle-lips, and have a finer appearance than in the other species; the interior of the orifices, in both, is covered with a layer of white pearly substance, almost luminous. In the foot of tuberculatum, which agrees in the particulars already mentioned with that of its congener, I observed a beautiful opalescent gleam, when under water.
I had supposed that they would display their instincts to more advantage if placed in circumstances more accordant to their habits. I therefore first imitated the sandy beach from which the tide has just retired, by laying my protegès on a bowl of wet sand; and afterwards placed them in a large vessel of sea water with a sandy bottom of several inches deep. But in neither case was there any correspondent action in the animals; they did not attempt to burrow, nor were they so active as when in the clean dish. Most of them soon died; one only, a large specimen of C. aculeatum, lived about ten days, in the circumstances last mentioned, content to lie submerged on the top of the sand; though the siphons, mantle, and foot indicated health, until the last day or two of its life. Sickness is marked, in these animals, by the lax state of the mantle, which permanently recedes from the foot, and gapes; by the softness of the foot, which is partially protruded; and by the shrinking of the siphons.
A considerable number of those sent up we "killed to save their lives;" making gastronomical use of them. The scalloped Cockles of Paignton we had known only by reputation; we tried them in this way, and found them worthy of their fame.
Mr. Kingsley has favoured me with the following observations on the respiration of these species. "Whether Mr. Clark be right or not in saying that the water is received through both siphons, he is right against Mr. Alder and Mr. Cocks, in saying that it is expelled through both. What I see is this. From the small anal siphon, the water is expelled in steady periodic currents, forming a ripple (under three inches of water) several inches off. From the large siphon it is expelled seldom and capriciously, in a violent jet; give ten a minute to the small, one in four or five minutes to the large. If disturbed they commonly jet the water from the large tube.
"The large siphon opens periodically,—I think answering to the jets of the small siphon,—till it is quite circular. The small one almost always keeps an oval form: I can see no inward current in either. Clark is right in saying that they lie long without using the siphons; sometimes they are not out for a whole day.
"What is the use of the fringes? They cannot strain the water in so large an animal as this Cockle, which, when the siphon is open, has a inch pipe fully patulous."
THE ROUGH SYRINX.
When once we have begun to look with curiosity on the strange things that ordinary people pass over without notice, our wonder is continually excited by the variety of phase, and often by the uncouthness of form, under which some of the meaner creatures are presented to us. And this is very specially the case with the inhabitants of the sea. We can scarcely poke and pry for an hour among the rocks at low-water mark, or walk with an observant downcast eye along the beach after a gale, without finding some oddly-fashioned, suspicious-looking being, unlike any form of life that we have seen before. The dark, concealed interior of the sea becomes thus invested with a fresh mystery; its vast recesses appear to be stored with all imaginable forms, and we are tempted to think there must be multitudes of living creatures whose very figure and structure have never yet been suspected.
"O Sea! old Sea! who yet knows half
- Of thy wonders or thy pride!"
Yet so full and close has been the attention with which the naturalists of the last hundred years have studied the forms and affinities of organic existence, that all these strange beings find their place in the arranged systems of Nature; and it is rare indeed to discover an animal or plant so diverse from those already familiar to us, that we are compelled to isolate it, or even to express uncertainty as to its general relations.
Among the treasures sent me by Mr. Kingsley was a specimen of the Rough Syrinx (Syrinx nudus), called by Pennant the Tube Worm. I presume it must be an unusually fine one of its kind, for, though it was my first acquaintance with the strange creature, and I therefore have no data for comparison derived from personal observation, Professor Forbes gives its length as ranging from six to eight inches. My specimen, however, measured eleven inches in length, though the posterior extremity was contracted, and the proboscis was but little everted, so that under other circumstances its length would certainly have exceeded a foot. The measurement was made, too, when the animal was at perfect rest, and not elongated by crawling. Its thickness was just 58ths of an inch, uniformly cylindrical, without any noticeable contractions or enlargements, except the swelling of the tail, and the diminution to form the proboscis.
The surface of the body can scarcely be called rough, for, though it is reticulated, the skin is delicately smooth, glossy, and iridescent. The reticulations are produced by longitudinal and transverse lines, the former about 112th, the latter 18th of an inch apart, very regular. Both series are indented striæ, becoming evanescent by being pressed out, when the body is swollen or bent. The hinder extremity, for about an inch, is nearly smooth, forming a swollen oval sac, the furrows of both series being lost on its upper half in irregular corrugations. This part is pearly white, but the whole body besides is of a dull greyish buff, the skin reflecting opaline tints.
The anterior extremity is suddenly diminished into a proboscis of about half the diameter of the body, which is capable of being concealed within the body, or protruded by being turned inside out like a stocking. Prof. Forbes says its surface is minutely granulated, but this expression does not convey a correct idea of its structure. It is densely covered with very minute triangular scaly spines, somewhat imbricate, the points of which are blunt, and are recurved. The resemblance borne by this organ to the proboscis in the parasitic Entozoa and Epizoa, is remarkable, and not only shows the affinity of the Syrinx to the vermiform classes, but suggests some analogy of purpose to which the spines are subservient. What the nature of the food is in the Syrinx, and what is the mode in which it is procured, I have no knowledge. I believe the subject is still in tenebris; but the stomach is said to be always filled with sand and minnute fragments of shells, between the swallowing of which and an elaborate prehensile array of recurved hooks, I certainly can imagine no connexion. The whole spinous surface of the proboscis is much more brilliantly iridescent than the body. The termination of this organ is said to be furnished with a circle of short digitate tentacles; but as the animal did not evert the proboscis to the full extent while I had it alive, I had no opportunity of observing these.
At a little more than an inch below the commencement of the proboscis there is a small tubercle, which I at first took for a wound, through which the intestine was protruding; but I believe it is the natural orifice of the digestive canal, which is said to be of great length, extending to the extremity of the body, and then turned on itself till it reaches this tubercle in its reverted course.
The animal was inert, scarcely moving, except when touched, and died after I had had it about a week.
THE TEREBELLA.
A rich fund of entertainment is very accessible to any one who can procure a few bits of weed-covered rock from the level of low-water. They need scarcely be selected: with a hammer knock off a few points of the stones, of the size of a crown-piece; the rougher, more leprous, more discoloured, in short, more dirty the better. Put them into a globe of sea-water, an uncut decanter, or a wide-mouthed bottle, or, best of all, a confectioner's show-glass, and let them remain for a few hours. At night examine the sides of the bottle carefully with a pocket-lens, placing a candle on the opposite side. The multitude of curious little creatures that will have crawled out, and will be found mounting the walls of their prison, is quite surprising. Minute Mollusca, both bivalve and univalve, uncouth-formed Crustacea, tiny Starfishes, and especially Annelida, will pretty certainly reward the investigator. The last-named Class occurs in remarkable abundance and variety; while if, after you have gone round the glass, noticing particularly the very edge of the surface-line, you pass your eye, assisted by the lens, carefully over the surfaces of the bits of stone, you will probably find many more creatures, such as tube-dwelling Annelides, the smaller Zoophytes, and several species of the delicate Bryozoa.
In a lot of sea-weeds sent up to me from the coast, enclosed in refuse-weed and tightly packed in a piece of canvas, I found among many such little things as I have described, a small Terebella, which interested me by a habit that I should not have suspected in the genus. It is a worm closely allied to the Sabellæ and Serpulæ, but having the head adorned with a great number of long thread-like tentacles, in place of the beautiful fans and other apparatus that distinguish those genera. In general the Terebella inhabits a tube, not formed of solid shell like that of the Serpula, nor of mud like that of the Sabella; but one most ingeniously fabricated by its own tentacles, built up of minute particles of sand or small fragments of shells, which it lays with elegance and neatness in a cement of its own construction. From the creation of the world this little worm has been practising the ancient and honorable craft of masonry, forming his vaulted tunnels of unhewn stones (for what are atoms of sand but stones?) and bedding them with Roman cement, that "sets" under water. And hence I would respectfully suggest to the worthy brotherhood of Free and Accepted Masons, whether they do not injustice to themselves in tracing their origin no farther than Father Adam, since assuredly the Terebellæ were not only brethren but masters of the craft, before he began existence,—by half a day at least.
If any of my readers should wish to see specimens of this ancient mason's art, nothing is easier than to gratify the desire. Go and turn over the loose stones that lie on the sandy shore along the line of low-water, and you will find in sufficient abundance sandy tubes of the size of a goose-quill, and several inches in length, so brittle as hardly to endure removal, imbedded in the earth. These are the habitations of T. chrysodon, most commonly empty and deserted; but not infrequently the long slender tentacles of this species, like orange-coloured animated threads, may be seen twining in all directions over the exposed soil. If you carefully look at the larger end of the tube, you will observe that it is irregularly fringed with threads of exactly the same texture as the tube itself; they are in fact minute tubes of the same shelly mosaic, though no thicker than stout sewing cotton, and most admirably constructed to sheath the tentacles as they project from the main tube, and expand on every side.
But it was not as a builder that I was going to introduce to you my little Terebella, which the candle revealed in the vase of sea-weeds, when I examined them the evening after their arrival. It was a little creature, not quite an inch long in the body, and with tentacles expanding about as much. Whether, finding itself in new quarters, it had left its dwelling to explore the neighbourhood, I know not,—possibly by careful search I might have found the emptied tube among the bases of the tufted weeds, or adhering to some of the pieces of stone on which they were growing;—but the naked worm was deliberately mounting the smooth side of the tall glass vessel. The body hung down, and the tentacles, some fifty or sixty in number, were spread out on each side and above, on the surface of the glass, adhering to it evidently, and alternately elongated and contracted, with an impatient writhing, twisting action, the result of which was to crawl, not very slowly either, up the glass.
After a time, I went into the room again, and found the Terebella in another situation, and performing a new feat; one even less to have been anticipated than the perpendicular wall-climbing I have described. It was now swimming on the surface of the water, or rather creeping along the inferior surface of the incumbent stratum of air (for that is the true expression of the action), as every one has observed the Pond Snails (Limnæa) to do in summer, and as the Nudibranchs, and many other Gasteropod Mollusca do also. It was interesting to see how much at home the little worm was at this performance; I doubt not he had enjoyed the fresh air in the same manner many a time; his body depended perpendicularly, while the thread-like tentacles were spread over the surface, wriggling and twining more suo, but advancing along the halcyon sea so evenly, that, in about an hour after, I saw that he had gained the opposite side of the bounding glass, a distance of about five inches.
THE GOLDEN-COMBED WORM.
These tube-forming Annelida are very interesting creatures; and many of them possess great beauty from the exquisitely delicate, and often highly coloured appendages with which they are furnished. Through the kindness of the Rev. C. Kingsley I possess a full grown specimen of the Golden-combed Worm (Amphitrite auricoma). When I at first had him he was very shy and timid, but after a week or two he grew more familiar, and would protrude his gilt combs, and carry on his avocations, as if quite at home. At first all that was to be seen was a tube formed like a rounded obelisk, or a factory chimney; being about one third of an inch in diameter at one end and gradually tapering to one fifth of an inch at the other, whence it abruptly terminated in a short cone, perforated in the centre. The whole length was an inch and a half, and its texture was that of an elegant mosaic, composed of grains of fine sand of various colours, and excessively minute fragments of shell, agglutinated together so as to be pretty strong, though not more than one grain thick. It was only with a lens that this structure could be seen; to the naked eye it seemed an uniform substance, slightly rough, and of a pale red hue, dotted with black.
On looking into the larger end of this tube, I could see what looked like a stopper of white flesh, exactly fitting the calibre, and moving up and down in the tube like a piston. Occasionally it was protruded a little beyond the edge, when its extremity was seen to be truncate, or, as it were, cut straight off, so that it was just like a cork that moves freely up and down in the neck of a bottle. But from the summit of this fleshy cork two organs were projecting, each of which exactly resembled a lady's back comb, the teeth being curved in the same manner; only we must suppose them to be bevelled off on each side, the central teeth of each comb being much the longest; their surface is highly metallic, reflecting the light exactly like burnished gold. These two combs are placed side by side, (or edge to edge) so that together they extend nearly all across the flat end of the "cork"; not however in a straight but an angled line, so as to cut off about 120°, or one third of the circle.
When the creature had overcome in some degree the timidity induced by its novel circumstances, such as the increased light, the slight depth of water, the heightened temperature, &c., it was interesting to watch its proceedings, especially at night, with a candle; as then it was more active. I had put it into a vase of water with two inches of fine siliceous sand for a bottom, on which the tube lay along. After a few tentative essays, it grew bold enough to thrust out its cork-like head, projecting the combs as it did so, so as to shew more of their bases. They thus separated from each other, and each assumed the form of a concave fan, or of a turkey's tail were the shafts of the feathers stripped of the vanes.
Their use was now apparent. The animal is a burrower in sand; I repeatedly lost it during my absence from the room, and found it plunged to the very bottom. Its mode of burrowing is as follows. If the animal is not lying rightly, it turns on its axis within the tube (which it can do with perfect facility, as there is no organic connexion between its body and its dwelling, as there is between a Mollusk and its shell), until the third of the circle inclosed by the angle of the combs is next the surface. These organs are now thrust outwards and downwards, so that their points enter the soil like shovels; then by muscular movements of the head they are lifted upwards and backwards, carrying in their concavity their load of sand, which they throw over the upper margin of the tube, behind the head. The combs, or, as I may now call them, digging-forks, immediately make another plunge, and deliver their spadeful of sand in like manner. A considerable hollow is presently formed, which a number of thread-like filaments protruded from the lower part of the head are engaged from time to time in feeling, and apparently examining. When this hollow is sufficiently wide and deep, the animal tilts its tube into it, by protruding until the weight of its body overbalances the supported part; it proceeds with its excavation, the tube becoming more and more inclined, until at length it is brought to the perpendicular, when it descends straight down till it is completely buried, the sand closing over its disappearing extremity.
This burrowing habit, the mouth of the tube being downward, makes it needful that there should be a posterior orifice in the tube. All the tribe to which this species belongs are nourished by those minute organic atoms which are held in suspension by the water, and which are brought by strong ciliary currents to the mouth. The currents thus produced are subservient to the two functions of respiration and digestion, the water thus hurled along giving off its Oxygen to the gills, and its organic atoms to the stomach. The refuse water, kept in unflagging motion by vigorous cilia, is poured from the terminal extremity of the body, and discharged through the minute orifice that I have described.
Dr. Williams, in his admirable 'Report on the British Annelida,' has, I think fallen into an error with regard to this species; or at least his statements in this particular do not agree with my own observation. After describing the mode in which the posterior extremity in A. alveolata is contracted into a true cylindrical tail, which, turning upwards, returns along parallel to the body, in order to project the fæcal refuse to the anterior extremity of the tube, he ascribes a similar structure to the present species. "In A. auricoma," he observes, the tail-like appendage to the inferior extremity of the body, in all respects but one, is formed on the model of that of the former species. One labium of the terminal orifice is here extended into a flap-like process, which, by a sudden act of muscular contraction, imparts a smart blow to the fæculent mass as it escapes from the intestine, and thus effectively conveys it to the upper outlet of the tube." (p. 208). Again, in treating of the alimentary system of the genera Serpula, Sabella and Amphitrite, he remarks that "it is through the agency of the water-current that traverses the whole interior of the body, that the fæculent refuse is projected from the bottom to the upper orifice of the tube, and that the habitation of the worm is maintained in a state of never-varying cleanliness and purity." (p. 225).
I am absolutely certain, however, that in my specimen of A. auricoma the discharge is terminal. As the animal lies on the bottom, a stream of water issues from the hinder end of the tube, not constant but intermittent, by which the adjacent sand is driven away with force, forming a furrow, a third of an inch long, extending from the end of the tube. The terminal portion of the tail itself is occasionally protruded through the aperture, and moved round with agility. When the tube with the contained animal is removed from the water and again replaced, a bubble of air escapes from the posterior orifice; and when the tube alone (the animal having deserted it) was held up full of water, the fluid ran out rapidly at the same aperture. The animal, also, which voluntarily crawled out of its habitation, displays no such reversion of the tail as is described by Dr. Williams. This organ is a little leaf-shaped body, formed by the union of several short segments, and slightly bent downward, but not reverted.
The quitting of its tenement by the Worm enabled me to see and admire some other points in its structure, and their subservience to its economy. On each side of the neck, just below the edge of the flat cork-like head, are seen two little scarlet gills, resembling in structure those of fishes. Each consists of a free leaflet, formed of numerous thin plates set face to face: in health these little pointed gills are thrown about with agility in various directions, and their points alternately coiled up and unfolded. Behind these, along each side of the body, are placed prominent fleshy warts, to the number of fifteen pairs; each of which consists of two portions, the hinder part being dilated into a soft transverse mop, and the fore part perforated to give exit to a brush of fine spears of elaborate construction. They are about twelve in each bundle, each formed of a long and slender, highly elastic, glassy shaft, terminated by a bent blade, the edge of which is of the most delicate thinness, and the point of which is drawn out to great length and tenuity. Some of the blades appear to be simple and knife-like, but others have the edge cut with oblique slits, parallel to each other, and pointing from the base. They do not form saw-teeth, but are merely straight slits. This bundle of lancets can be protruded at will to a considerable length, or withdrawn into the fleshy wart so as to be quite concealed, as in a sheath. Their direction is backward, and their main use is doubtless that of catching against the internal walls of the tube, and pushing the animal outwards. At the same time it is not improbable that their cutting edges serve to cut and dress the fragments of sand of which the tube is composed; and that the spongy cushions behind the bundles help to bring the work to that state of polished smoothness, which is needful to guard the soft and tender body of the Annelide from annoyance.
SUICIDE.
Some time ago a humorous periodical favoured the public with a portrait of "a Prime Minister" a-bolishing of his self." The marine naturalist is aware that the process is occasionally exhibited by other animals also; the faculty may perhaps be the link, which in a quinary arrangement connects the Prime Ministers with the Echinoderms. Certainly the latter possess this useful faculty in extraordinary perfection, as witness the triumphant way in which Luidia fragilissima laughed at Professor Forbes.[1] A swell-gentleman in Regent Quadrant could not have "done" a police officer in more admirable style.
The Brittle-stars (Ophiocoma), as their name imports, are considered peculiarly prone to this suicidal work; but, for my own experience, though I have dredged a tolerable quantity (I say "quantity" because Brittle-stars come up in pecks or bushels rather than in scores or hundreds), and have had plenty of examples of disjointed members, I have never found it prevail to such an extent as to prevent my preserving almost with certainty any specimen I wished, without particular precautions. And certainly they are charming occupants of an Aquarium: the extreme variety of colouring displayed by them,—I speak of the most abundant species, the Rosette (O. rosula)—and the gorgeousness of the hues frequently presented, orange, yellow, crimson, purple, blue, white; often arranged in alternate angular bands; catch the eye of the most indifferent in a moment: while the exquisitely sculptured spines that profusely fringe each ray, and the many-sided and variously-formed, but perfectly regular and symmetrical scales and plates, that clothe the disk and the rays on both surfaces, elicit our admiration when we examine them more closely. (See Plate IV.)
Professor Forbes is "doubtful, however, whether Uraster (the common Starfish, Crossfish or Five-finger) has the power of throwing off its rays voluntarily, as is the case with Luidia and the Ophiuræ." I have had evidence that it has, and that not in the case of U. glacialis, in which species these organs are acknowledged to be fragile, but in the Common Crossfish (U. rubens).
A specimen of this latter about five inches in diameter, that had been dredged in Weymouth harbour, was crawling tranquilly up the glass side of my large tank. Several hours had elapsed since it was put in, and it had appeared quite at home, and was as lively as could be desired. It had three full-sized rays, and two very small ones, doubtless reproducing. Suddenly, without any apparent provocation, it threw off one of the large rays. I did not see the process, but I had looked at it a moment before, and at the next glance the patient was marching calmly on as before with one of his legs an inch behind him. The suckers of the rejected ray were still as active as before, alternately loosening their hold and adhering, just as before, but there was no advance.
Seven hours afterwards, when I retired to bed, the suckers of the ray were still moving, and the ray maintained its adhesion to the perpendicular side of the glass; as it did also when I got up the next morning. But by this time four more rays were separated, and were adhering by their suckers to the upright glass just where they had been left: while the body pursued its solitary journey solaced by the fidelity of its sole remaining ray,—one of the large ones.
My curiosity had been excited by the fact that I could not determine with certainty the point from which the first rejected member had separated. I examined the animal minutely, but so entire seemed the whole skin, and so equidistant the remaining rays, that I could not satisfy myself, though I returned again and again to the scrutiny. I did not, however, choose to handle the animal much. But now that so many limbs were gone the points of separation were just visible, yet the contraction of the surrounding parts was so great that the wounds were exceedingly small. The separation was in each case exactly the same, by an oblique cut, as it were, upward and outward, close to the body; and perfectly clean, without laceration, and without any perceptible flow of liquid.
I carefully slit up with scissors one of the separated rays, and found within it the bulbs of the numerous suckers, of course, and the two cæca of the intestine, beautifully arborescent, and of a yellowish-olive colour; so that in the voluntary throwing off of a limb, these digestive organs are not absorbed or contracted into the body, but cast off also.
The Starfish continued to walk about, like a Chelsea pensioner, on his one leg, till the afternoon of this second day, when the remaining limb dropped off by its own weight, on my lifting the animal from one vessel to another. I took great care of the body, hoping that it might reproduce the lost limbs while in my possession; but I was disappointed. It never moved after this last amputation, and putrefaction soon made it too manifest that death had ensued.
The Holothuriæ, or Sea-Cucumbers, those members of the Class Echinodermata, which, to the locomotive suckers and other essential organs of the Starfishes and Sea-urchins, conjoin some peculiarities, such as the elongate form, and a circle of oral tentacula, which are considered to approximate them to the Worms (Annelida), or, perhaps more truly, to the Actiniæ,—usually commit suicide in a different manner. According to the concurrent testimony of observers, they frequently disgorge from the mouth, the stomach, intestines, and ovary, "leaving the body an empty sac;" and occasionally throwing off even the tentacles, the mouth, and the dental cylinder. But some species of these are said to "divide spontaneously through the middle into two or more parts, all becoming ultimately perfect by the development of new organs."[2]
This spontaneous division I lately had an opportunity of witnessing in a Echinoderm of great rarity, so rare that I know not whether any British zoologist has seen it before, since its discovery on the South Devon Coast by Montagu. Professor Forbes says he had never met with a living example. I allude to Chirodota digitata.
Many living specimens of this species were forwarded to me by the kindness of the Rev. C. Kingsley, who obtained them in the vicinity of Torquay. He says, "I got this and Actinia chrysanthellum in two contiguous coves, washed up after a heavy gale [in January] in company with Lutraria elliptica, and the common red hag-worm, indicating life on a mud-sand bottom."
This animal is a very worm-like Holothuria, nearly cylindrical in form when in health. The largest of my specimens extended to ten inches, with an average diameter of one-fourth of an inch. The posterior extremity is always plump and rounded, sometimes swollen to an oval sac, half an inch in diameter and two inches long. The body is covered with annular striæ, most distinct on the fore half.
Notwithstanding the cylindrical form, a dorsal and a ventral side may be readily distinguished. The former has, as its general colour, a hue approaching to the Indian-red of artists, while the latter is of a pale pellucid flesh-colour. The body is marked by five longitudinal colourless lines, of which the dorsal ones are only half as broad as the ventral. Under a lens the ground colour is resolved into a number of minute red dots, thickly placed dorsally, and often becoming confluent into longitudinal dashes, but placed thinly on the belly.
The anterior extremity forms a disk surrounded by a marginal circle of twelve short tentacula. These organs are rather thick columns, with their bases in contact, tapering to the tip, where each branches into four short diverging fingers, which are likewise taper and pointed. The red speckling extends up the tentacles. The mouth is a cup-shaped circular cavity, whose edges reach to the bases of the tentacles.
The dental cylinder of the Holothuriæ is represented by a slender ring of minute white calcareous pieces, varying in size, and irregular in form. None of them are larger than 125th of an inch square. They are united by cartilage into an elastic ring, running round the base of the tentacular circle.
While in captivity the motions of these animals were quite vermicular, slowly twisting the long body into knots and contortions, and writhing about. The tentacles were now and then bent inward to the mouth, one or two at a time, and then unfolded. They did not long retain the cylindrical form in which I received them; very soon one after another began to constrict the body into knobs at irregular intervals, occasionally so forcibly as to separate into two or many pieces. Sometimes the division was incomplete, so that the intestines, and especially the long generative threads were forced out abundantly from the constriction. But these latter must be described particularly.
Each of the animals, as soon as it had arrived at this stage of its suicidal process, was seen to be wrapped up in a swathing-band of white threads, which, issuing in a bundle from the rupture, soon became involved in inextricable confusion by the writhings and knottings of the animal. The threads were of great length, and closely resembled in appearance white sewing-cotton. The microscope revealed their structure. They were not ciliated, and therefore had no spontaneous motion, in these respects differing from the convoluted filaments of the Actiniæ, to which they bear great affinity. The common texture was composed of a multitude of very minute round granules of hyaline and nearly colourless jelly, about 15000th of an inch in diameter, having no motion when crushed down. In this granular substance were set numerous ova, ranging from 1195th to 1250th of an inch in diameter. These consisted of a hyaline integument, including an opaque brown granular yelk, sometimes nearly filling the interior, at others occupying not more than two thirds of it. Within the yelk in each there was a well-defined, globular, hyaline nucleus. On continued pressure the integument burst with a start and a loud crepitation; the yelk oozed through the rupture, retaining its integrity, though its elastic form changed as it passed through the narrow aperture: the nucleus was also compressible and elastic, escaping entire, a clear globular vesicle.
I was in hopes that this spontaneous protrusion of the egg-tubes was a normal process, and that by keeping the animals I might witness the development of the eggs and young, especially after what Sir John Dalyell and others have observed in the Holothuriæ. But I found that the self-divided animals very soon became offensive and evidently putrescent, an infallible evidence that death had ensued; and that not only was this the case with the posterior portions separated from the main body, but with the latter also, or that to which the head was attached. It is possible that the whole process was caused by morbid muscular contraction, arising from the stimulus of unnatural circumstances. Mr. Kingsley suggests to me that "the animal breaks itself up from the irritation of light," a suggestion highly probable; and that we "must keep it in the shade if we obtain it again."
One which I put into fresh water, in order to kill it for preservation, immediately began to contract, and continued the process (not rapidly) to rigidity. It then lengthened again, distended the posterior extremity, and then divided by constriction near the middle, protruding the intestine, but no ovigerous threads. The body, after lying a while, discharged a stain, which diffused itself to some distance through the water, and precipitated a subtle sediment of a brilliant gamboge hue, which increased to saffron. The whole water in the saucer was, besides, slightly tinged with pink. The specimen, on being immersed in a preservative fluid—a solution of acetate of alumina and sulphate of potash,—tinged the lower parts of it with a rich transparent crimson, a little inclined to purple, the hue of which was deepest near the bottom.
The vermiform figure of this animal, its swollen posterior extremity, and its tendency to irregular constriction, combine with the absence of suckers, and the deterioration of the oral tentacles to mark its affinity with the Sipunculidœ, in which family I think it should be placed. I know the characters of the genus Chirodota of Eschscholtz, only from their citation in Professor Forbes' "Star-fishes," but cannot help thinking with Montagu that our Torquay specimens come very close to Müller's Holothuria inhærens, judging from the figure and Latin diagnosis of the latter, for unfortunately I cannot read the Danish language. The only difference I notice is in the form of the tentacles, Müller's species having each sixteen terminal digitations, while ours has but four.
THE PHYLLODOCE.
Many of the Marine Worms, as I have before said, are very elegant creatures, and not a few present us with great variety and brilliance of colours. Pre-eminent among them are the Leaf-worms, according to the verdict of most who have studied this Class of beings, from Fabricius downward, who styled them Virgines pulcherrimæ inter Nereides." In the little shallow hollows that are to be found on the surface of the rocks covered at high tide, green with the puckered leaves of the lettuce-like Ulva, and affording a happy home to multitudes of Purples, Periwinks, Tops and Mussels, we may often see, gliding in and out, the worms of this genus, which the indefatigable Savigny named after the sea-nymph Phyllodoce;—
"Phyllodoceque
Cæsariem effusæ nitidam per candida colla."
Virgil.
These worms bear a general resemblance to the Centipedes of the land, and some may behold them with aversion on that account; but, prejudice being laid aside, we must confess that their forms are elegant, their motions lithe, easy and full of grace, and their general appearance attractive. They are distinguished by their long, slender, and flattened bodies, composed of very numerous segments, sometimes amounting to several hundred (as in the case of Phyllodoce laminosa, Sav. found on the French side of the Channel, which reaches to two feet in length, and is divided into more than 500 segments[3]); but they may be more readily recognised by the series of overlapping leaflets which run along each side, one pair to each segment.
It is a very curious spectacle to see these Worms turn the stomach inside out. In common with most other genera of this Class, the head is minute, and what seems to be the mouth, is but the orifice from which the proboscis is protruded. In the genus Phyllodoce, this organ is a great muscular sac, sometimes as much as one-fourth of the whole length of the body. The beholder is astonished to see a chasm in the under side of the head begin to yawn, and the interior rapidly protrude, turning inside-out as it comes forth, like a living stocking, until it assumes the form of an enormous pear-shaped bag, the surface of which is beset with a multitude of secreting warts or glands, like those which stud the tongue in higher animals. In many genera the extremity of this stomach, throat, or proboscis is furnished with a formidable apparatus of horny grasping jaws, variously modified into teeth, hooks and knife-blades, for seizing, tearing and cutting prey; but in Phyllodoce, there are none of these, the elegant animals feeding probably on the fluid juices of dead animals, or on their soft parts, which need no violence. The very tip, however, which of course is perforated, is surrounded by a muscle, by means of which it contracts forcibly on whatever it is applied to, and thus holds it firmly while the inversion of the sac drags it into the body to be digested. The disappearance of the organ is as astonishing as its extrusion; beginning at the tip, which is quickly turned in, the whole rapidly returns to its cavity in the same order as it came out, and then we wonder how so enormous a proboscis can be enclosed in so slender a body.
There is one species of this genus, very common in the situations I have mentioned, named Ph. lamelligera; which is of a yellowish-green, sometimes verging to an olive hue. But a much more beautiful kind has been sent me alive from Torquay, by the courtesy of Mr. Kingsley, who found it beneath a stone at the edge of the laminarian level. I can find nothing corresponding to it either in Audouin and M. Edwards, or in Dr. Johnston's papers on the British Annelida, and shall therefore describe it under the appellation of P. marginata.
Its length varies from five to three inches, according as it is elongated or contracted; the body is composed of about 170 segments, nearly of equal diameter throughout, and abruptly rounded at both extremities. The segments are bordered by oval, puckered leaflets, the colour of which, being almost black, with an edging of light yellow green, gives the animal a most beautiful appearance, somewhat resembling that of a number of black velvet palls with their light fringes. The central part of the back is of a steel-blue, changing under the play of light to purple, with a highly metallic reflection. The under surface is of an opalescent grey.[4]
The beauty in a great measure disappears on immersion in a preservative fluid. On the first touch of the solution I employ (Acetate of Alumina), a fluid was poured out copiously from all parts of the animal, which diffused itself, first as a lively green tint, then becoming yellow, which in about an hour became a warm orange-brown, quite transparent and without precipitation.
The various kinds of spears which are grouped into pencils, and placed along the sides of most of the animals of this Class, are among the most exquisite productions with which the naturalist is conversant, and show forth in a more than ordinary degree the delicate and inimitable skill of the Divine handiwork. In this animal they are less complicate than in some of which I have had occasion to speak; still, under a high microscopic power they are well worthy of admiration. In order to understand their arrangement, let me say, that each segment of the body is produced on each side into a little conical wart-like foot, on the upper side of which is attached by a short footstalk the beautiful pall-like leaflet, and on the under side a similar smaller one, the tip of the foot projecting between them. This point is perforated to give emission to the pencil of bristle-spears, which are arranged like a fan, and are, at the will of the animal, projected to a considerable length from the foot, or withdrawn completely into its interior, as into a sheath. Each individual bristle is composed of a very slender, long, straight shaft, terminating in a knob somewhat resembling the end of a limb-bone. This is slit in one direction to receive the terminal lance-head, which is fitted into it exactly as a knife-blade is fixed into its handle. It is in fact a knife-blade having a thickened back, and a very thin edge, which is notched with teeth of the most delicate subtilty. The blade is slightly curved, and drawn out to a long acute point; and the whole space is formed out of a substance that rivals the purest glass.
The full use of these most exquisitely contrived and finished organs is, I think, yet to be discovered. They are doubtless instruments of locomotion, being evidently used to push the animal along, as a ferry-man propels a boat with his pole; and the saw-like teeth may serve to catch the roughnesses of the surfaces along which it is moving. It is possible also that they may be weapons of defence; for, being thrust out at every laternal undulation of the segments, they present formidable chevaux de frise to any small enemy who may entertain malice prepense againt the Annelid. Still the situation of these arms is hardly such as we should expect, if this were their primary object; and the elaborate construction of their jointed blades seems contrived for some use more delicate than that of a shoving-pole. Perhaps my readers may expect that I have some suggestion to make, but I am sorry to say I have not. I have not been able to discover any function that these elegant and exquisite implements possess in addition to those just mentioned, though I have little doubt that such function is to be discovered. It is a common phenomenon for the same organ to have two or more distinct and separate uses. The human tongue and palate play an important part in tasting food and preparing it for swallowing, and also in the utterance of speech; and in the worm before us, the beautifully-painted leaflets are organs of respiration, the blood (or rather, according to Dr. Williams, the peritoneal fluid) circulating through them in spacious radiating canals, and receiving oxygen from the currents which the marginal cilia perpetually impel across their surface; but they are also organs of locomotion; waved through the water, and half-turned when the stroke is made,—as the waterman "feathers" his oar,—it is easy to see that the animal is actually rowed along, like one of the galleys of the ancients, with a bank of three hundred oars "Natare valet lamellis suis retroversis, oblique sursum erectis,"—observes Fabricius of these elegant animals.
The following observations, whose beauty and truth necessitate no apology for their quotation, are made by one who is perhaps better qualified than any one else to express a judgment on these creatures, from the care and labour which he has bestowed on the study of them.
"It is not easy to express the pleasure which is excited in the mind of the observer of nature, while contemplating the habit and manners of the Annelida. Every movement exemplifies the curve of beauty; every tentacle winds ceaselessly and rapidly through a thousand forms of matchless grace. Whether coiling round a visible object, or picking up a microscopic molecule for the construction of the cell, it exhibits a delicacy and precision of aim, which the erudite finger of the most skilful artisan never equalled. The refined precision of its muscular performances, is matched only by its exquisite sensibility. Like the human hand, of which the manifold endownments have exhausted the admiring eloquence of philosophers and theologians, it unites in its little self the most varied capacities. It is at once an eye, an ear, a nose, and a finger: it sees, it hears, it smells, it touches. Leading for the most part a subaqueous or subterranean life, the sense of sight in the Annelid is little required; and gifted in every part of the body with a superlative tenderness of touch, the sense of hearing is rendered unnecessary. Anatomy accordingly demonstrates only the obscurest rudiments of an organ of vision, while that of hearing has eluded the scrutiny of the minutest examination. Is it not to be marvelled at, that these humble beings should see without eyes, and smell without a nose? It is not affirmed that this is literally and entirely true; but it is exact to a degree enough to prove the wondrous manner in which the sense of touch is made to supersede all the other senses.
"Whether progressing on the solid surface, or moving through water, or tunneling the sand, advancing or retreating in its tube, the Annelid performs muscular feats, distinguished at once for their complexity and harmony. In grace of coil the little Worm excels the Serpent. In regularity of march the thousand-footed Nereid out-rivals the Centipede. The leaf-armed Phyllodoce swims with greater beauty of mechanism than the Fish, and the vulgar Earthworm shames the Mole in the exactitude and skill of its subterranean operations. Why then should "the humble worm" have remained so long without an historian? Is the care, the wisdom, the love, the paternal solicitude of the Almighty not legible in the surpassing organism, the ingenious architectures, the individual and social habits, the adaptation of structure to the physical conditions of existence, of these degraded beings? Do not their habitations display His care, their instincts His wisdom, their merriment His love, their vast specific diversities His solicitous and inscrutable Providence?"[5]