In his celebrated journey to the western islands of Scotland, Dr. Johnson tells us that when at Ulinish, hearing of a cavern by the sea-side remarkable for powerful reverberations of sound, he determined to pay a visit to the spot. After dinner, having procured the services of some boatmen, the doctor, in company with Bozzy, started off on his trip, which, on the whole, appears to have been a pleasant one. There was, however, no echo to be heard; but to make up for this disappointment, Mr. Boswell went angling, and caught a wee 'cuddy,' (a fish about the size of a gudgeon), while the doctor was gratified by the sight of some sea-weed growing upon stones, and above all, at witnessing for the first time Mussels in their natural state.

The impression made by this candid acknowledgment upon our minds is one of wonder, that a man like Johnson could have reached his advanced years without having seen so common a sight. But it is possible that even in our day, with its unprecedented facilities for cheap travelling for the most inland inhabitants, there may be many persons to whom the sight of a Mussel fixed to a boulder by its self-constructed cable, would be as great a novelty as it was to the eloquent author of Rasselas.

It is, however, one of the commonest appearances which meet the eye of those in the habit of visiting the sea-shore. At certain localities myriads of Mussels may be noticed attached to the surface of the rocks. So thickly are these sometimes covered over, that the blade of a knife cannot be inserted at any part without touching one or more of the esculent bivalves that are to form the subject of this chapter.

The Mussel anchors itself by means of the Byssus; or, as it is commonly termed, the 'beard.' This appendage is composed of various slender threads which are attached to any object within reach, whether such be the shell of a neighbouring Mussel, a small stone, or huge boulder. The members of each colony are thereby bound together, it may be figuratively said, by the silken cords of friendship, and mayhap of love. The Mytili evidently believe that 'there's no place like home.' Although gifted with a power of moving about at will, they never attempt to exercise this when living together in a family circle, but pass through life's stages upon the spot where they were born. Certainly, if there be such a sight as a truly happy and contented family in the marine animal kingdom, it is to be found exemplified in these bearded molluscs.

As hinted, they live shoulder to shoulder, back to back, and otherwise mutually support each other. They need not look about for a single meal, but have merely to allow themselves to be fed by the waves, which yield them a constant supply of fresh and wholesome food. Their sole duty in this respect is limited to the selection of objects suitable to their palate. Their 'at homes' being so frequent, the Mytili can boast of a large circle of acquaintances. The Periwinkle, and his friend Silver Willie, often make a morning call, take pot luck, as it is termed, and then politely retire. Mr. Carcinus MÆnas and his poor and dirty relation, Maia Squinado, perchance look in of an evening. Solaster Papposa, or occasionally the lanky-legged Uraster Rubens, and other 'stars' of the marine world, crawl in at unseasonable hours in their usual lazy style, and are generally rewarded by finding the doors (valves) shut against them. This 'cut direct' does not appear to be at all annoying; or if so, the Star-fishes are too cunning to show it, for they quietly saunter away as if they never had the slightest wish to put their feet within their neighbour's dwelling.

There is a 'black sheep,' as Sir Pertinax Mac Sycophant would say, who intrudes himself into Mussel society, and plays sad havoc among its members. This crawling rascal is the wolf of all Musseldom flocks. Young and old alike experience the blighting effects of his villanous propensities. The name of this obnoxious personage is Purpura Lapillus (Common Whelk). What, the reader will ask in surprise, a univalve prey upon a bivalve? Is that possible? It is, unfortunately, too true.

If we take a Mussel in our hand we shall find it perfectly impossible to force its valves asunder, without the aid of a strong knife or other instrument; yet the Common Whelk, fleshy and insignificant creature though it be, will consume the animal within, and make the valves fly open in a brief space of time, by means of its soft tongue. But leaving such general remarks, let us suppose we are standing before a boulder covered with these mussels. Numbers of gaping shells may be at intervals perceived still attached to the rock, but with the interior of each valve so empty and smooth, that we could scarce believe they had ever embraced a living occupant. On taking up one of the valves and closely examining it, do you observe nothing peculiar about it now? 'No.' Take up the other then, and submit it to a similar inspection. Well, what do you see now? 'Nothing,' you still reply, 'unless it be a peculiar little hole about the size of a pin's head, which surely is of no importance.' That little hole was of vital importance to the poor mollusc, for through that aperture the life and substance of the Mytilus was drawn by the voracious Purpura.

But the poor Mussel is exposed to the attacks of other enemies—aquatic birds, as sea-gulls and ducks, eagles, vultures. Even water-rats and monkeys may also be included in the list.

It is amusing to see a gull, by no means a foolish bird, standing patiently before a Limpet, for example. The animal, unsuspicious of the presence of an enemy, raises his canopy with the view of relaxing his overstrained muscles, and is instantly toppled over by the intruding beak of the bird. If unsuccessful in his first attempt, the gull is well aware it would be useless to try a second time at that tide.

But if a Mussel be the object of attack, it is wrenched from its seat, raised to a certain height, and then allowed to drop upon a stone with the view of breaking the shell. In one locality called Mussel Bay, Mr. Barrow says he disturbed some thousands of birds, and found so many thousands of shell-fish scattered over the surface of a heap of shells, that, for aught he knew, would have filled as many thousand waggons.

This habit of the feathered tribe was, by the way, well known to the ancients, and I may be pardoned relieving my pages by a quotation on the subject from the 'Shepherd's Calender' of Spenser, whose exquisite descriptions of natural history are as marvellous as his allegorical poem. The author of the 'Fairy Queen' thus humorously reads a lesson to an ambitious man,—

It seems remarkable that the 'illustrious French naturalist,' Reaumur, should have been the first, if not to discover, at least to publish, any description of the manner in which the Mussel spins its silken cable. Yet one hour's experience in a tea-cup or tumbler will exhibit most of the features in this interesting process.

That Reaumur's narrative, although usually copied by most writers of the present day, is not strictly correct, and, moreover, that the foot of the mussel is not 'useless as an instrument of progression' (as generally asserted), may be easily proved to the satisfaction of the student by adopting some such simple experiment as that which I am now about to describe:—

Being at the sea-side on a fine summer afternoon, I procured three specimens (I might have had as many hundreds if disposed) of the Mytilus. On my return home I placed them in a common tumbler, and waited patiently to see the result. My object was, if possible, to witness the manner in which this animal grows its beard.

In less than five minutes an industrious little fellow, whom we will call No. 1, gently opened his shell, and immediately protruded his fleshy foot until it reached a length of nearly two inches. So far as I could determine, the design of the Mussel was to discover, in the first place, what kind of a lodging he occupied; whether or not he had any companions; and also, to know if these or any other objects could be found worthy of his attachment.

Sometimes the foot would be protruded under the shell, then in a contrary direction. Or by an exertion of the strong muscular power which that organ possesses, the entire shell would be lifted off the ground and urged forward to a considerable distance. Of course he soon come in contact with a neighbour Mussel, whom we may term No. 2, but as the latter was not anchored by any byssus, he was speedily pushed on, and on, until No. 3 was met, and the latter, in his turn, made to take up a new position.

Being tired of wandering about, No. 1 then extended his foot along the base of the vase to a certain point, and there let it rest for a few seconds. When again withdrawn, to my great delight, I saw the first thread of a new byssus had been constructed.

As my principal object was to become acquainted with the mode of formation of the beard, I did not feel satisfied with merely watching the movements of the animal from above. After a brief interval another thread was spun. I bore in mind the words of Reaumur, who says, 'The Mussel never spins more than four or five threads in the twenty-four hours.' Aware that no time must be lost, though still afraid to disturb the mollusc lest it might suspend its labours, I instantly detached my specimen, and again turned its shell round so as to bring the opening of the valves against the face of the glass. The creature did not seem at all offended at his handiwork having been destroyed, but still obstinately refused to let me see the working of its foot. Again was the shell rolled over, and again did I replace it in its former position. This time, in order to keep it from being shifted, a stone was deposited upon the valve. Nothing daunted, the animal gradually separated the valves of its shell, and at the same time advanced and elevated its foot to the exact position that I had so long desired.

The spinner, when at its full length, was pressed firmly upon the flat surface of the glass, and there allowed to remain for a while. Suddenly, at nearly half an inch distance from its extreme end (or point), a little mouth was seen to form, about the size of a large pin's head, from which there issued a milk-white fluid, that gradually hardened and became fixed to the glass. This object being light in colour, had a pretty effect when contrasted with the rich brown tint of the spinner. Shortly afterwards the foot rolled over and withdrew into the shell, leaving behind it the silken thread which had just been spun. The 'little mouth,' above described, was, if I may so term it, the mould in which the end of the thread was cast.

In the course of two hours a bundle of byssus threads, sixteen in number, were produced by this industrious little labourer.

Having thus seen that the foot is useful to the Mussel as an instrument of progression before the beard is formed, let me now endeavour to show that it is, at times, of equal service for the same object, after, and when the mollusc is anchored thereby to any particular spot.

When we remember that this anchorage is formed of a harp-like set of strings, amounting to ten or even a hundred in number, it does seem an almost incredible fact that the Mytilus is enabled to change its station, even when living in single blessedness.

To see a Mussel 'flit,' is a sight one may often watch and wait for without success. On the other hand, when least expected, the self-willed mollusc may commence operations. When about to take up a new home, the animal shaves off its beard entirely, or in more scientific language, 'rejects its byssus' altogether. In order to excite the locomotive instincts of my specimens, I used to cut all the threads of their cable except one. The animal being suspended, of course its whole weight was then thrown upon a single fibre. Such a state of insecurity was by no means agreeable, and I generally found in the course of a few hours that fresh threads were rapidly thrown out, and an entirely new byssus formed; the old one, which was broken off at the root, being left behind as useless.

Another singular peculiarity of the Mussel which came under my observation has not been, so far as I am aware, noticed by previous naturalists. I allude to the power which the animal possesses of lengthening out the root or stem of the beard, apparently to an unlimited extent. This power appears to be seldom exercised, for although I have had hundreds of specimens of the Mytili, in only one instance have I witnessed the phenomenon in question.

A large specimen of this bivalve, procured accidentally from a fishwife in the street, was dropped into the aquarium, and placed close against the surface of the glass. The animal seemed highly delighted with its change of situation, for in a few moments the valves were opened, and a long draught of water taken in to bathe its branchiÆ, and furnish a hearty meal. Having satisfied its appetite, the next process, of course, was to find out what kind of a home he had been introduced into. The foot, a noble specimen, was soon protruded, and one after the other, in rapid succession, various threads were formed. By next morning the animal, advancing by a series of easy stages, had reached the surface of the water, which was exactly five inches deep. I knew it would not remain long in this position, and was anxious to discover what plan would next be adopted. Several courses were open to him. For instance, like a marine Captain Cook, he might circumnavigate his little Globe,—or he might let go his cable and drop plump to the bottom,—or he could follow the route I had often seen taken by his relations, viz., to journey back to the place from whence he started. It pleased him, however, to strike out into a new path,—to devise a method of his own. While located near the top of the tank, he threw out exactly ninety-eight threads, not certainly for security, but merely, it would appear, for pleasure.

Then slowly but surely, day by day, he lengthened out the stem of his byssus tree, until it reached the extreme length of nearly five inches. To what further degree it would have been extended, had the mollusc not reached the base of the tank, it is impossible to conjecture.

No sooner did the shell touch terra firma, than the cable which had taken so long to spin was immediately broken off. I have succeeded in keeping the same animal by me for the last twelve months, but have seen no attempt at a renewal of the operation, in the progress of which I had taken so lively an interest. I may add that this Mussel taught me another lesson; it was this: in my early studies regarding the habits of the Mytilus, I had adopted a certain theory of the manner in which the beard was formed; and having watched so long, and witnessed the process so repeatedly, I thought myself justified in forming certain conclusions. My belief was that the creature could not form more than one thread at a time, without withdrawing its foot into the shell, as I believed, in order to procure a fresh supply of material. That this notion was erroneous, this animal proved to my entire satisfaction. Not only may one, but two, three, four, and even six threads be attached to any selected object, the point of the foot being passed from one position to another, without the organ being withdrawn into the valves until the whole of the threads are formed. How many more the Mussel is capable of producing at one 'stretch,' I have no means of knowing, but six is the largest number that any of my specimens in such case have ever fabricated.

The general idea seems to be that the Mussel works in the same manner as the spider, who emits a drop of liquid against some foreign substance, which, being allowed to harden somewhat, is then drawn out as the spider recedes. This notion, I may state, is quite erroneous. When the sucker of which we have spoken is formed, the thread is completed. It is true that the foot as it retires into the shell generally glides down the newly-constructed filament, but this is not of necessity, nor does such circumstance invariably occur. Indeed, while busily engaged in attaching a disc to the glass, the muscles of the foot will contract, and thus throw open the folds of the groove, situated in the middle of that organ; when thus exposed, the byssus thread may be seen in the furrow, stretched like the string of a harp or dulcimer.

While the end of the thread is being attached to a certain spot, a conspicuous muscular action is perceived going on in the foot, which alternately swells and contracts, as if something were being pumped up through the byssal channel, until it reached a certain point. There being dilated and spread out in successive layers, it assumes a trumpet-like disc, which is firmly fixed to the foreign object. Indeed, I am by no means certain that the thread is not, when first produced, exactly like a trumpet in shape. It also conveys the idea of being blown out in a similar manner to a piece of bottle glass. After being exposed to the air for some little time, the hollowness of the thread is not so apparent as when it is newly fabricated.

The mucous fluid, from which the fibres are formed, is secreted in a gland situated at the base of the foot, whence it is apparently expelled at the will of the animal into the furrow already referred to, and is there spun into threads. The toughness of these filaments, considering that each is finer than the thinnest strand of silk, is remarkable. Their strength, however, may be easily accounted for, when we know that each is composed in reality of innumerable delicate threads, bound together by a subtle gelatinous fluid. This phenomenon may be made out quite distinctly with a common hand lens, if the following simple experiment be adopted: Make a Mussel construct its thread in such a way that the disc of each is planted on the face of the glass. Then place the fine point of a common needle upon the outer edge of a chosen disc or sucker, and gently draw the former away to a little distance, and you will find that by so doing the stretched string becomes peeled. Continue this process carefully, and before the thread gives way you will have divided it into a dozen parts at least, all of which are visible to the naked eye, but clearer when the hand lens is used, and still more distinctly and beautifully defined, of course, if the microscope be brought into play.

The foot of the Mussel appears to be firmly strapped on, as it were, to certain transverse muscles, by a contraction of which the animal closes its shell with surprising force. This strap, composed of a powerful tendon which passes under the adductor muscles, is attached at either end to the base of the foot. Thus we account for the remarkable strength which is evidently seated in the foot, and makes it of so much importance to the animal. At first sight nothing appears more easy than to pluck out this organ by the roots, but an attempt will prove the experiment to be more difficult than many persons suppose.

The colour of the foot varies considerably in different specimens, even of the same species. Some, for instance, are of a chestnut brown; others of a kind of mauve or purple, covered with a peach-like bloom during life; others, again, are of a deep-toned umber, while not a few are pearly white, and streaked sometimes with pink like a tulip.

The peculiarity of the Mussel to attach itself to foreign substances has been taken advantage of for the benefit of man, and a curious instance is exhibited at Bideford in Devonshire, at which town there is a bridge of twenty-four arches, stretching across the Torridge river near its junction with the Taw. 'At this bridge the tide flows so rapidly that it cannot be kept in repair by mortar. The corporation, therefore, keep boats in employ to bring mussels to it, and the interstices of the bridge are filled by hand with these mussels. It is supported from being driven away entirely by the strong threads these mussels fix to the stonework.'

Like most other writers who quote this strange account, I have not had ocular proof of its accuracy.[9] That it is quite probable I can readily believe, as a pretty experiment will partly prove it to any spirited aquarian. Following out the above idea of the bridge at Bideford, I managed to build an exceedingly pretty centre piece for my tank.

Having no ready means of making a rock arch, I collected such pieces of rock, stones, &c., with weeds attached, as I thought would answer my purpose, and then proceeded to fabricate the object of my wishes in the following simple way: First were laid two stones parallel to each other at three or four inches apart. Upon these I placed a large piece of rock in a transverse direction. Between the interstices a number of small mussels were then inserted. When fully satisfied that the bivalves had moored themselves, I gradually piled one piece of rock upon another until the structure reached the desired height, each piece being bound to its neighbour by means of the byssus threads of the Mytili.

Before each block of stone that formed the foundations of the arch was placed a splendid frond of Lettuce Ulva, tied by a strand of silk to a white pebble. These verdant fronds, so smooth in texture and so gracefully convoluted, rising up from the base of the tank and reaching to its brim,—mingling, too, with the various tufts of corallines and other sea-weeds that jutted from each crevice, were very pretty to look at. When disturbed by the movements of the fishes passing in and out, the gracefulness and beauty of the sea-weed was doubly increased.

In making observations upon any bivalve, such as the Mussel, it is extremely puzzling to know what is going on inside the shell. Yet it is almost necessary to acquire this knowledge by means not always apparent, in order to satisfy one's mind relative to certain appearances, which we perceive going on externally. We have to form our judgment of things we do not see from those that are apparent—at all times a difficult task. But not often so tantalizing as in the case of an insignificant creature like the Mussel, who lives, moves, and works constantly before our eyes. I may add that it was not enough for me that I saw the spinning process frequently. It all seemed tolerably clear to my mind, but still I did not feel thoroughly satisfied. My desire was to peep into the shell, and find out where the last spun thread was situated; or, in other words, from what part of the trunk the new branch sprung. On examining various specimens of the byssus, this point was by no means apparent. Various means I adopted failed to secure me the requisite knowledge. At length I hit upon a plan, which, after no long time, I found opportunity to put in practice. My largest Mussel lifted up its testaceous canopy, put aside the fringed and fleshy veil that surrounded its edge, protruded its spinner to make sure the ground was secure, and then withdrew it again into the shell as usual. After the lapse of a second, the foot reappeared and was stretched out to an unusual length. No sooner was the end of the thread formed on the glass than immediately I firmly pressed the valves together, and held them in this position until I had gradually worked the Mussel up out of the vase, when I bound them close together by means of a piece of cord. I need not describe my manoeuvres further; suffice it to say that the thread nearest to the base of the groove was found to be the one that was spun last. This, in my opinion, is invariably the case.

I may mention that the above experiment also proved to my mind that the foot must be a most important vital organ of the Mytilus. At times, on placing an open Mussel in my tank as food for crabs or other animals, I have noted that if every other part were eaten, and the foot allowed to remain attached to the muscles of the bivalve, that member would after a lapse of several days show signs of—I do not say life—but sensation and retractile power.

But when the foot is cut and otherwise injured, the animal dies quickly. In the experiment mentioned the valves were not kept closed for more than half an hour; yet when they were opened, vitality had evidently ceased within. This was the more singular when we remember that the Mytili will live for many days out of the water; the shells, of course, during the whole period being firmly closed.

The Mussel, as already hinted, is very tenacious of life. I have kept specimens by accident for several days in the pocket of my coat, but found them quite well and lively when placed in sea-water.

In general the sure sign of their not being in a healthy condition is when the shell opens; for, while the animal retains any sense whatever, it exercises a strict and judicious 'closeness.'

I have found, however, on several occasions, that the shell being contracted is not always a valid proof of its owner's convalescence, for when placed in water the Mussel would float for several days upon the surface like a cork, although it was near death's door.

This phenomenon must be caused, I should suppose, by some sudden fright compelling the mollusc to close its shell with such rapidity as to prevent a proper supply of water being taken in. Having only air to exist upon, the animal then lingers on until its branchiÆ become dried up, and all moisture exhausted. In this state the Mussel opens its shell with a deep bursting sigh, and sinks to the bottom—dead.

Being at the sea-side one fine summer day, I heard a little Scotch girl cry out to her brother who was about to swallow entire, a fine specimen of the Mytilus edulis, 'Eh, Willie dear, dinna ye eat that. Dinna eat the beard or ye'll dee!' Many years ago I remember a remark to the same purport as the above being made by a poor child to its playmate, in the neighbourhood of Gravesend.

I little thought at that time that the Mussel was so interesting a shell-fish, or that I years after should spend many an anxious hour studying the formation and nature of its despised beard.

I need hardly state that the idea of the beard being poisonous is a vulgar error. In general the fish may be eaten entire with impunity.

Cases have occurred where persons have been taken ill after eating it, but this result has been satisfactorily explained to have been caused by the Mussels being procured from places such as Leith Docks, where their food consisted chiefly of unwholesome and putrescent matters.

This mollusc is not used as food to any very great extent by the poorer classes. It is employed very extensively, however, by the fishermen as bait along all parts of the British coast. But in France it is much esteemed both by rich and poor. The trade in them is successfully cultivated, and affords a means of support to hundreds of industrious and deserving men.

From the learned author of the "Rambles of a Naturalist" we learn that at the village of Esnandes, on the coast of France, the Mussel trade, commenced about eight hundred years ago, has assumed a gigantic extent. Both here and at the neighbouring villages of Charron, Marsilly, Mussels are bred in an ingenious and systematic manner. At the level of the lowest tide short piles or stakes are driven into the mud, in a series of rows about a yard apart. This palisade is then roughly fenced in with long branches. On this structure the Mussel spawn is deposited, and it is found that the molluscs thus produced in the open sea are much finer than those which are bred nearer the shore.

These artificial Mussel beds are termed 'bouchots.' The fishermen who engage in this branch of industry are known as 'boucholeurs.'

'The little Mussels,' continues M. Quatrefage, 'that appear in the spring are known as seeds. They are scarcely larger than lentils, till towards the end of May, but at this time they rapidly increase, and in July they attain the size of a haricot bean. They then take the name of renouvelains, and are fit for transplanting. For this purpose they are detached from those bouchots, which are situated at the lowest tide mark, and are then introduced into the pockets or bags made of old nets, which are placed upon the fences that are not quite so far advanced into the sea. The young Mussels spread themselves all round the pockets, fixing themselves by means of those filaments which naturalists designate by the name of byssus. In proportion as they grow and become crowded together within the pockets, they are cleared out and distributed over other poles lying somewhat nearer to the shore, whilst the full-grown Mussels which are fit for sale are planted on the bouchots nearest the shore. It is from this part of the Mussel bed that the fishermen reap their harvest, and every day enormous quantities of freshly gathered Mussels are transported in carts or on the backs of horses to La Rochelle and other places, from whence they are sent as far as Tours, Limoges, and Bordeaux.... The following data, which were collected by M. D. Orbigny more than twenty years ago, will show how important this branch of industry must be to the district in which it is cultivated. In 1834 the three communes of Esnandes, Charron, and Marsilly, representing a population of 3000 souls, possessed 340 bouchots, the original cost of which was valued by M. D. Orbigny at 696,660 francs; the annual expenses of maintaining them amounted to 386,240 francs, including the interest of the capital employed, and the cost of labour, which, however, is spared to the proprietor who works on his own account. The nett revenue is estimated at 364 francs for each bouchot, or 123,760 francs for the three communes. Finally, the expense of the carts, horses, and boats, employed in transporting the Mussels, then amounted annually to 510,000 francs; but these numbers are far from representing the expenses or profits at the present day. At the time M. D. Orbigny lived at Esnandes, the bouchots were only arranged in four rows; now however, there are no less than seven rows, and some of them measure more than 1000 yards from the base to the summit. The whole of these bouchots, which were at first limited to the immediate neighbourhood of the three villages, of which I have already spoken, extend at the present day uninterruptedly from Marsilly far beyond Charron, and form a gigantic stockade for two miles and a half in breadth, and six miles in length.'

A curious circumstance connected with the Mytilus remains to be described. Let the reader, who may be so fortunate as to possess a good microscope, cut away a portion of the fleshy part of the Mussel, then place it in a watch glass, and examine it through that 'portal to things invisible,' and, unless I am much mistaken, he will own the sight to be supremely wonderful. Some water being deposited in the glass the fleshy object will be seen to swim about in a most singular and mysterious manner, while a close inspection shows every portion of it to be in active motion.

This motive power is caused by countless cilia, the rapid vibration of which creates constant currents. This action preserves the health of the poor mollusc by Ærating the water which passes over his respiratory organs.

That some such wonderful contrivance is adopted, for conveying food within the valves, too, is evident, when we consider that the Mussel is always affixed to some foreign substance, that it cannot hunt after prey, and therefore can subsist only upon whatever nutritious particles may be contained in the element in which it lives. These consist of minute animalculÆ, principally crustacea, which are drawn within the shell by powerful currents.

I have often watched this phenomenon through a hand lens, and have seen the young shrimps and skip-jacks, for instance, notwithstanding the nimbleness of their movements, irresistibly drawn into the gulf of destruction. Even tolerably sized specimens that were seated in fancied security upon a valve of the Mussel, have suddenly been drawn in, out of sight. As an instance of the power of these currents, I may state that the water in a small aquarium is often seen to be affected by the respiratory action of a single bivalve. The same thing has even been apparent to the writer, while watching the movements of a colony of Barnacles attached to a Limpet, the most distant part of the fluid being gradually drawn near, in obedience to the beck of these delicate and graceful little creatures.