CHAPTER VI.

CORALLINES.

"As for your pretty little seed-cups or vases, they are a sweet confirmation of the pleasure Nature seems to take in superadding elegance of form to most of her works. How poor and bungling are all the imitations of art! When I have the pleasure of seeing you next, we shall sit down--nay, kneel down--and admire these things."--HOGARTH TO ELLIS.

The Alcyonaria are so designated from their principal type, that of the Alcyons. The fresh-water species are composed of a fleshy, sponge-like mass, consisting of vertical, aggregated, membranaceous tubes, which are open on the surface. In these tubes the polyps, which are Isidians, are located. The mouth is encircled with a single series of filiform tentacula, which, like those of the whole family, are depressed or incomplete on one side. The eggs are contained in the tubes, and are coriaceous and smooth. The tentacula of these polyps are generally eight, disposed somewhat like the barbs of a feather, and toothed on their edges like a saw, which has procured them the name of _Ctenoceros_, from the Greek word χτεις, a comb. Their bodies present eight perigastric lamellæ; their coral is often formed of spiculæ. We shall see, farther on, that among the Gorgonidæ the coral ceases to be parenchymous--that is, spongy and cellular; that its axis assumes a horny and resistant consistence, which becomes stony in the corallines. In this last group, the external bed, which is the special lodging of the polyps, always remains soft on the surface. We shall have a general idea of the organization, manners, and mode of multiplication among the Alcyonaria when we come to treat of corals and their strange history. The class Alcyonaria is divided into many orders. We shall consider--I. The _Tubiporinæ_. II. The _Gorgoniadæ_. III. The _Pennatulidæ_. IV. The _Alcyonaria_, properly so called.

I. THE TUBIPORINÆ

form a group consisting of several species, which live in the bosom of tropical seas, in which the Coral Islands form so prominent a feature. The group is exclusively formed of the curious genus _Tubipora_.

The _Tubipora_ is a calcareous coral, formed by a combination of distinct, regularly-arranged tubes, connected together at regulated distances by lamellar expansion of the same material. The aggregate formation resulting from this combination of tubes constitutes a rounded mass, which often attains a very considerable size. In Fig. 41 we have a representation of the zoophyte _Tubipora musica_ and its product, which is sometimes designated by the vulgar name of Sea-Organ. In the engraving, 1 is the calcareous product, reduced to half its size; 2, is a portion in its natural size; 3, the tubes magnified, and containing the polyp which occupies the summit of the tube, the whole of which constitutes this curious coral; 4, is the polyp magnified; 5, the head or collection of tentacula of the individual polyp.

Zoologists of the last century confounded all the species of this genera inhabiting the tropical seas, making only one species, to which they gave the name of _Tubipora musica_. But it is now known that there are many species of _Tubiporæ_, readily distinguishable in a fresh condition by a difference in the colour of the polyps. The tissue of these singular beings is of an intensely red colour. The disposition of their tubes in the style of organ pipes has always attracted the attention of the curious inquirer into the secrets of Nature.

II. GORGONIADÆ.

Milne Edwards divides this order into three natural groups:--I. The _Gorgoniadæ_. II. The _Isidians_. III. The _Corallines_.

The _Gorgonians_ are composed of two substances: the one external, sometimes gelatinous and fugitive; sometimes, on the contrary, cretaceous, fleshy, and more or less tenacious. Animated with life, this membrane is irritable and encloses the polyp; it becomes friable or arenaceous in drying. The second substance, internal and central, sustains the first, and is called the _axis_. This axis presents a horny appearance, and was formerly believed to possess chemical characters analogous to the horns and hoofs of some of the vertebrated animals. It has recently been asserted that the tissues of these corals consist essentially of a particular substance which resembles horn, but which is called _Corneine_. A little carbonate of lime is sometimes found united with this substance, but never in a sufficient quantity to give it a stony consistence. This outer covering developes itself in concentric beds, between the portion of the axis previously formed and the internal surface of the sclerotic covering.

The mode of growth in this axis presents great variations. Sometimes it remains simple and rises like a slender rod, sometimes it has numerous branches. It is _arborescent_ when the branches and their accompaniments take different directions so as to constitute tufts. It is _panicled_ when they arrange themselves on both sides of the stem or principal branches, after the manner of the barbs of a feather. It is _flabelliform_ when the branches rise irregularly under the same plane; _reticulated_, when branches are so disposed as to be attached to each other by network in place of remaining free.

The _Gorgoniadæ_ are found in every sea, and always at considerable depths. They are larger and more numerous between the Tropics than in cold or even temperate climates. Some of these corals scarcely attain the twelfth of an inch in height, while others rise to the height of several feet.

Formed in the bosom of the ocean, it is only necessary to behold these singular creations in order to admire the brilliant colours which decorate their semi-membranaceous branches. The brilliancy of their robes are singularly diminished, have almost entirely disappeared, indeed, when they make their appearance in the cases of our natural history collections.

The _Fan Gorgon_, from the Antilles (Fig. 42), is a species which often attains the height of eighteen or twenty inches, and nearly as much in breadth. The network of its interstices with its unequal and serried meshes, resembling fine lace, have led to its designation of _Sea Fan_. Its colour is yellow or reddish. In Fig. 43 we have the _Sea Fan_ magnified to twice its natural size, showing the curious details of its organization.

The Whorled Gorgon (_G. verticellata_), which is found in the Mediterranean, is yellowish in colour, and also of elegant form. It is sometimes called the Sea Pen. This species is represented in Fig. 44, while Fig. 45 represents a small branch magnified four times, in order to give an exact idea of its form.

The Gorgons are not known to be useful either in the arts or in medicine. They are ornamental in cabinets, and interesting both as objects of study and of zoological curiosity.

ISIDIANS.

The _Isidæ_ constitute an intermediate group between the _Gorgons_ and _Corallines_. Their polypidom is arborescent, but its axis is formed of articulations alternately calcareous and horny. The principal genus is that of the _Isis_, which is met with in the Indian Ocean, on the American coast, and in Oceania. The inhabitants of the Molucca Islands use these animals medicinally as a remedy in certain diseases; but as they use them for the most opposite maladies, it may be doubted if they are really efficacious in any medicinal point of view.

The _Isis corolloïdis_ of Oceania has a coral with numerous slender branches, furnished with cylindrical knots at intervals, contracted towards the middle, finely striated, and rose-coloured. _Isis_ _hippuris_, represented in Fig. 46, has a singular resemblance to the Common Mare's Tail (_Hippuris vulgaris_).

Four other species of Isidians are known. The same family includes the genera of _Melitæa_ and _Mopsea_, which, however, our limits forbid us to describe.

CORALLINÆ.

The group of Corallines consist of a single genus, _Corallium_, having a common axis, inarticulate, solid, and calcareous, the typical species of which furnishes matter hard, brilliant, and richly coloured, and much sought after as an object of adornment. This interesting zoophyte and its product require to be described with some detail.

From very early times, the coral has been adopted as an object of ornament. From the highest antiquity, also, efforts were made to ascertain its true origin, and the place assignable to it in the works of Nature. Theophrastus, Dioscorides, and Pliny considered that the coral was a plant. Tournefort, in 1700, reproduced the same idea. Réaumur slightly modified this opinion of the ancients, and declared his opinion that the coral was the stony product of certain marine plants. Science was in this state when a naturalist, who has acquired a great name, the Count de Marsigli, made a discovery which threw quite a new light on the true origin of this natural product. He announced that he had discovered the flowers of the coral. He represented these flowers in his fine work, "La Physique de la Mer," which includes many interesting details respecting this curious product of the ocean. How could it be longer doubted that the coral was a plant, since he had seen its expanded flowers?

No one doubted it, and Réaumur proclaimed everywhere the discovery of the happy Academician.

Unhappily, a discordant note soon mingled in this concert. It even emanated from a pupil of Marsigli!

Jean André de Peyssonnel was born at Marseilles in 1694. He was a student of medicine and natural history at Paris when the Académie des Sciences charged him with the task of studying the coral on the sea-shore. Peyssonnel began his observations in the neighbourhood of Marseilles in 1723. He pursued it on the North African coast, where he had been sent on a mission by the Government. Aided by a long series of observations as exact as they were delicate, Peyssonnel demonstrated that the pretended flowers which the Count de Marsigli thought he had discovered in the coral, were true animals, and showed that the coral was neither plant nor the product of a plant, but a being with life, which he placed in the first "rung" of the zoological ladder. "I put the flower of the coral," says Peyssonnel, "in vases full of sea-water, and I saw that what had been taken for a flower of this pretended plant was, in truth, only an insect, like a little sea-nettle, or polyp. I had the pleasure of seeing removed the claws or feet of the creature, and having put the vase full of water, which contained the coral, in a gentle heat over the fire, all the small insects seemed to expand. The polyp extended his feet, and formed what M. de Marsigli and I had taken for the petals of a flower. The calyx of this pretended flower, in short, was the animal, which advanced and issued out of its cell."

The observations of Peyssonnel were calculated to put aside altogether theories which had lately attracted universal admiration, but they were coldly received by the naturalists, his contemporaries. Réaumur distinguished himself greatly in his opposition to the young innovator. He wrote to Peyssonnel in an ironical tone: "I think (he says) as you do, that no one has hitherto been disposed to regard the coral as the work of insects. We cannot deny that this idea is both new and singular; but the coral, as it appears to me, never could have been constructed by sea-nettles or polyps, if we may judge from the manner in which you make them labour."

What appeared impossible to Réaumur was, however, a fact which Peyssonnel had demonstrated to hundreds by his experiments at Marseilles. Nevertheless, Bernard de Jussieu did not find the reasons he urged strong enough to induce him to abandon the opinions he had formed as to their vegetable origin. Afflicted and disgusted at the indifferent success with which his labours were received, Peyssonnel abandoned his investigations. He even abandoned science and society, and sought an obscure retirement in the Antilles as a naval surgeon, and his manuscripts, which he left in France, have never been printed. These manuscripts, written in 1744, were preserved in the library of the Museum of Natural History at Paris. The title is comprehensive and sufficiently descriptive. It should be added, in order to complete the recital, that Réaumur and Bernard de Jussieu finally recognized the value of the discoveries and the validity of the reasoning of the naturalist of Marseilles. When these illustrious _savants_ became acquainted with the experiments of Trembley upon the fresh-water hydræ; when they had themselves repeated them; when they had made similar observations on the sea anemone and alcyonidæ; when they finally discovered that on other so-called marine plants animalcules were found similar to the hydra, so admirably described by Trembley;--they no longer hesitated to render full justice to the views of their former adversary.

While Peyssonnel still lived forgotten at the Antilles, his scientific labours were crowned with triumph at Paris; but it was a sterile triumph for him. Réaumur gave to the animalcules which construct the coral the name of _Polyps_, and _Coral_ to the product itself, for such he considered the architectural product of the polyps. In other words, Réaumur introduced into Science the views which he had keenly contested with their author. But from that time the animal nature of the coralline has never been doubted.

Without pausing to note the various authors who have given their attention to this fine natural production, we shall at once direct our attention to the organization of the animalcules, and the construction of the coral.

M. Lacaze-Duthiers, professor at the Jardin des Plantes of Paris, published in 1864 a remarkable monograph, entitled "L'Histoire Naturelle du Corail." This learned naturalist was charged by the French Government, in 1860, with a mission having for its object the study of the coral from the natural history point of view. His observations upon the zoophytes are numerous and precise, and worthy of the successor of Peyssonnel; but for close observation, practical conclusions, and popular exposition, the world is more indebted to Charles Darwin than to any other naturalist.

A branch of _living_ coral, if we may use the term, is an aggregation of animals derived from a first being by budding. They are united among themselves by a common tissue, each seeming to enjoy a life of its own, though participating in a common object. The branch seems to originate in an egg, which produces a young animal, which attaches itself soon after its birth, as already described. From this is derived the new beings which, by their united labours, produce the branch of coral or polypidom.

This branch is composed of two distinct parts: the one central, of a hard, brittle, and stony nature, the well-known coral of commerce; the other altogether external, like the bark of a tree, soft and fleshy, and easily impressed with the nail. This is essentially the bed of the living colony. The first is called the polypidom, the second is the colony of polyps. This bed (Fig. 47) is much contracted when the water is withdrawn from the colony. It is covered with salient mammals or protuberances, much wrinkled and furrowed.

Each protuberance encloses a polyp, and presents on its summit eight folds, radiating round a central pore, which presents a star-like appearance. This pore as it opens gives to the polyps the opportunity of coming out. Its edge presents a reddish calyx, like the rest of the bark, the festooned throat of which presents eight dentations.

The polyp itself (Fig. 48) is formed of a whitish membranous tube, nearly cylindrical, having an upper disk, surrounded by its eight tentacula, bearing many delicate fibres spreading out laterally. This assemblage of tentacula resembles the corolla of some flowers; its form is very variable, but always truly elegant. Fig. 49 (which is borrowed from M. Lacaze-Duthiers' great work) represents one of these forms of the coral.

The arms of the polyps are at times subject to violent agitation: the tentacula become much excited. If this excitement continues, the tentacula can be seen to fold and roll themselves up, as shown in Fig. 50. If we look at the expanded disk, we see that the eight tentacula attach themselves to the body, describing a space perfectly circular, in the middle of which rises a small mammal, the summit of which is occupied by a small slit like two rounded lips. This is the mouth of the polyps, the form being very variable, but well represented in Fig. 50, where the organ under consideration is displayed.

A cylindrical tube connected with the mouth represents the oesophagus or gullet; but all other portions of the digestive tube are very rudimentary. The oesophagus connects the general cavity of the body with the exterior, and looks as if it were suspended in the middle of the body by certain folds, which issue with perfect symmetry from eight points of its circumference. The folds which thus fix the oesophagus form a series of cells, above each of which it attaches itself, and supports an arm or tentaculum.

Let us pause an instant over the soft and fleshy bark in which the polyps are engaged. Let us see also what are the mutual relations which exist between the several inhabitants of one of these colonies, how they are attached to one another, and what is their connection with the polypidom.

The thick fleshy body, soft, and easily impressed with the finger, is the living part which produces the coral; it extends itself so as exactly to cover the whole polypidom. If it perishes at any one point, that part of the axis which corresponds with the point no longer shows any increase. An intimate relation, therefore, exists between the bark and the polypidom. If the bark is examined more closely, three principal elements are recognized--a common general _tissue_, some _spicula_, and certain _vessels_. The general tissue is transparent, glossy, cellular, and contractile.

The _spiculæ_ are very small calcareous concretions, more or less elongated, covered with knotted joints bristling with spines, and of regular determinate form (Fig. 51). They refract the light very vividly, and their colour is that of the coral, but much weaker, in consequence of their want of thickness. They are uniformly distributed throughout the bark, and give to the coral the fine colour which generally characterises it.

The vessels constitute a network, which extends and repeats itself in the thickness of the crust. These vessels are of two kinds (Fig. 52); the one, comparatively very large, is imbedded in the axis, and disposed in parallel layers; the others are regular and much smaller. They form a network of unequal meshes, which occupies the whole thickness of the external crust. This network has direct and important connection with the polyps on the one hand, and with the central substance which forms the axis on the other. It communicates directly with the general cavity of the body of the animal, by every channel which approaches it, while the two ranges of network approach each other by a great number of anastomosing processes. Such is the vascular arrangement of the coral.

The circulation of alimentary fluids in the coral is accomplished by means of vessels near to the axis, without, however, directly anastomosing with the cavities containing the polyps which live in the polypidom; they only communicate with those cavities by very delicate intermediary canals. The alimentary fluids they receive from the secondary system of network, which brings them into direct communication with the polyps. The alimentary fluids elaborated by the polyps pass into the branches of the secondary and irregular network system, in order to reach the great parallel tubes which extend from one extremity of the organism to the other, serving the same purpose to the whole community.

When the extremity of a branch of living coral is torn or broken, a white liquid immediately flows from the wound, which mingles with water, and presents all the appearance of milk. This is the fluid aliment which has escaped from the vessel containing it, charged with the débris of the organism.

What occurs when the bud produces new polyps? It is only round well-developed animals, and particularly those with branching extremities, in which this phenomenon is produced. The new beings resemble little white points pierced with a central orifice. Aided by the microscope, we discover that this white point is starred with radiating white lines, the edge of the orifice bearing eight distinctly-traced indentations. All these organs are enlarged step by step until the young animal has attained the shrub-like or branched aspect which belongs to the compound polypidom. The tube is branching, and the orifices from which the polypi expand become dilated into cup-like cells.

The coral of commerce, so beautiful and so appreciated by lovers of bijouterie, is the polypidom. It is cylindrical, much channeled on the surface, the lines usually parallel to the axis of the cylinder, the depressions sometimes corresponding to the body of the animal. If the transverse section of a polypidom be examined, it is found to be regularly festooned on its circumference. Towards its centre certain sinuosities appear, sometimes crossing, sometimes trigonal, sometimes in irregular lines, and in the remaining mass are reddish folds alternating with brighter spaces which radiate from the centre towards the circumference (Fig. 53). In the section of a very red coral, it will be observed that the colour is not equally distributed, but separated into zones more or less deep in colour, containing very thin preparations which crack, not irregularly, but parallel to the edge of the plate, and in such a manner as to reproduce the festoons on the circumference. From this it may be deduced that the stem increases by concentric layers being deposited, which mould themselves one upon the other. In the mass of coral certain small corpuscles occur, charged with irregular asperities, much redder than the tissue into which they are plunged. These are much more numerous in the red than in the light band, and they necessarily give more strength to the general tint.

To the mode of reproduction in the coral polyps, so well described by Lacaze-Duthiers, we can only devote a few lines. Sometimes, according to this able observer, the polyps of the same colony are all either male or female, and the branch is _unisexual_; in others there are both male and female, when the branch is _bisexual_. Finally, but very rarely, polyps are found uniting both sexes.

The coral is viviparous; that is to say, its eggs become embryos inside the polyp. The larvæ remain a certain time in the general cavity of the polyp, where they can be seen through its transparency, as exhibited in Fig. 54. Aided by the magnifying powers of the microscope, coral larvæ may here be perceived through the transparent membranous envelope. From this position they escape from the mouth of the mother in the manner represented in the upper branch. The animal then resembles a little white grub or worm, more or less elongated. The larva is, however, still egg-shaped or ovoid; moreover, it is sunk in a hollow cavity, and covered with cilia, by the aid of which it can swim. Sometimes one of its extremities becomes enlarged, the other remaining slender and pointed. Upon this an opening is formed communicating with the interior cavity: this is the mouth. The larvæ swim backwards; that is to say, with the mouth behind.

It is only at a certain period after birth that the coral polyp fixes itself and commences its metamorphoses, which consist essentially in a change of form and proportions. The buccal extremity is diminished and tapers off, whilst the base swells, and is enlarged--it becomes discoid; the posterior surface of this sort of disk is a plane, the front representing the mouth, at the bottom of a depression edged with a great cushion. Eight mammillations or swellings now appear, corresponding to the chambers which divide the interior of the disk: the worm has taken its radiate form. Finally, the mammals are elongated and transformed into tentacula. In Fig. 55 a young coral polyp is represented fixed upon a bryozoa, a name employed by Ehrenberg for zoophytes having a mouth and anus. It forms a small disk, the fortieth part of an inch in diameter, and having its spicula already coloured red. Fig. 56 shows the successive forms of the young polyps in the progressive phases of their development--being a young coralline polyp fixed upon a rock still contracted. Fig. 57 is a similar coralline attached to a rock and expanding its tentacula. Fig. 58 represents a small pointed rock covered with polypi and polypidoms of the natural size and of different shapes, but all young, and indicating the definite form of development which the collective beings are to assume.

The simple isolated state of the animal, whose phases of development we have indicated, does not last long. It possesses the property of producing new beings, as we have already said, by budding. But how is the polypidom formed? If we take a very young branch, we find in the centre of the thickness of the crust a nucleus or stony substance resembling an agglomeration of spicula. When they are sufficient in number and size, these nuclei form a kind of stony plate, which is imbedded in the thickness of the tissues of the animal. These _laminæ_, at first quite flat, assume in the course of their development a horse-shoe shape. Figs. 59 and 60 will give the reader some idea of the form in which the young present themselves. Fig. 59 represents the corpuscles in which the polypidom has its origin; Fig. 60, the rudimentary form of the coralline polypidom.

Our information fails to convey any precise notion of the time necessary for the coral to acquire the various proportions in which it presents itself.

Darwin, who examined some of these creatures very minutely, tells us that "several genera" (Flustræ, Escharæ, Cellaria, Cresia, and others) agree in having singular movable organs attached to their cells. The organs in the greater number of cases very closely resemble the head of a vulture; but the lower mandible can be opened much wider than a real bird's beak. The head itself possesses considerable powers of movement, by means of a short neck. In one zoophyte the head itself was fixed, but the lower jaw free; in another it was replaced by a triangular hood, with a beautifully-fitted trap-door, which evidently answered to the lower mandible. In the greater number of species each cell was provided with one head, but in others each cell had two.

"The young cells at the end of the branches of these corallines contain quite immature polypi, yet the vulture heads attached to them, though small, are in every respect perfect. When the polypus was removed by a needle from any of the cells, these organs did not appear to be in the least affected. When one of the vulture-like heads was cut off from a cell, the lower mandible retained its power of opening and closing. Perhaps the most singular part of their structure is, that when there are more than two rows of cells on a branch, the central cells were furnished with these appendages of only one-fourth the size of the outside ones. Their movements varied according to the species; but in some I never saw the least motion, while others, with the lower mandible generally wide open, oscillated backwards and forwards at the rate of about five seconds each turn; others moved rapidly and by starts. When touched with a needle, the beak generally seized the point so firmly that the whole branch might be shaken."

In the _Cresia_, Darwin observed that each cell was furnished with a long-toothed bristle, which had the power of moving very quickly; each bristle and each vulture-like head moving quite independently of each other; sometimes all on one side, sometimes those on one branch only moving simultaneously, sometimes one after the other. In these actions we apparently behold as perfect a transmission of will in the zoophyte, though composed of thousands of distinct polyps, as in any distinct animal. "What can be more remarkable," he adds, "than to see a plant-like body producing an egg, capable of swimming about and choosing a proper place to adhere to, where it sprouts out into branches, each crowded with innumerable distinct animals, often of complicated organization!--the branches, moreover, sometimes possessing organs capable of movement independent of the polypi."

* * * * *

Passing to the coral fishing, it may be said to be quite special, presenting no analogy with any other fishing in the European seas, if we except the sponge fisheries. The fishing stations which occur are found on the Italian coast and the coast of Barbary; in short, in most parts of the Mediterranean basin. In all these regions, on abrupt rocky beds, certain aquatic forests occur, composed entirely of the red coral, the most brilliant and the most celebrated of all the corals, _Coralium decus liquidi_! During many ages, as we have seen, the coral was supposed to be a plant. The ancient Greeks called it the _daughter of the sea_ (Κορύλλιου κόρη ἁλός), which the Latins translated into _corralium_ or _coralium_. It is now agreed among naturalists that the coral is constructed by a family of polyps living together, and composing a polypidom. It abounds in the Mediterranean and the Red Sea, where it is found at various depths, but rarely less than five fathoms, or more than a hundred and fifty. Each polypidom resembles a pretty red leafless under shrub bearing delicate little star-like radiating white flowers. The axes of this little tree are the parts common to the association, the flowrets are the polypi. These axes present a soft reticulated crust, full of little cavities, which are the cells of the polyps, and are permeated by a milky juice. Beneath the crust is the coral, properly so called, which equals marble in hardness, and is remarkable for its striped surface, its bright red colour, and the fine polish of which it is susceptible. The ancients believed that it was soft in the water, and only took its consistence when exposed to the air:--

"Sic et coralium, quo primum contigit auras Tempore, durescit."

OVID.

The fishing is chiefly conducted by sailors from Genoa, Leghorn, and Naples, and it is so fatiguing, that it is a common saying in Italy that a sailor obliged to go to the coral fishery should be a thief or an assassin. The saying is a gratuitous insult to the sailor, but conveys a good idea enough of the occupation.

The barks sent to the fishing range from six to fifteen tons; they are solid, and well adapted for the labour; their rig is a great lateen sail, and a jib or staysail. The stern is reserved for the capstan, the fishers, and the crew. The fore part of the vessel is reserved for the requirements of the patron or master.

The lines, wood, and irons employed in the coral fisheries are called the _engine_: it consists of a cross of wood formed of two bars, strongly lashed or bolted together at their centre; below this a great stone is attached, which bears the lines, arranged in the form of a sac. These lines have great meshes, loosely knotted together, resembling the well-known swab.

The apparatus carries thirty of these sacs, which are intended to grapple all they come in contact with at the bottom of the sea. They are spread out in all directions by the movement of the boat. The coral is known to attach itself to the summit of a rock and to develop itself, forming banks there, and it is to these rocks that the swab attaches itself so as to tear up the precious harvest. Experience, which in time becomes almost intuitive, guides the Italian fisher in discovering the coral banks. The craft employed in the great fishery have a "patron" or captain, the bark having a poop, with a crew of eight or ten sailors, and in the season it is continued night and day. The whole apparatus, and mode of using it, is shown in PL. III.

When the patron thinks that he has reached a coral bank, he throws his engine overboard. As soon as the apparatus is engaged, the speed of the vessel is retarded, the capstan is manned by six or eight men, while the others guide the helm and trim the sails. Two forces are thus brought to act upon the lines, the horizontal action of the vessel and the vertical action of the capstan. In consequence of the many inequalities of the rocky bottom, the engine advances by jerks, the vessel yielding more or less, according to the concussion caused by the action of the capstan or sail. The engine seizes upon the rugged rocks at the bottom, and raises them to let them fall again. In this manner the swab, floating about, penetrates beneath the rocks where the coral is found, and is hooked on to it. To fix the lines upon the coral and bring them home, is a work of unheard-of labour. The engine long resists the most energetic and repeated efforts of the crew, who, exposed almost naked to the burning sun of the Mediterranean, work the capstan to which the cable and engine are attached, while the patron urges and excites them to increased exertion, and the sailors trim the sail and sing with a slow and monotonous tone a song, the words of which improvise in a sort of psalmody the names of the saints most revered among the seafaring Italian population.

The lines are finally brought home, tearing or breaking blocks of rock, sometimes of enormous size, which are brought on board. The cross is now placed on the side of the vessel, the lines are arranged on the deck, and the crew occupy themselves in gathering the results of their labour. The coral is gathered together, the branches of the precious zoophyte are cleansed, and divested of the shells and other parasitic products which accompany them; finally, the produce is carried to and sold in the ports of Messina, Naples, Genoa, or Leghorn, where the workers in jewellery purchase them. Behold, fair reader, with what hard labour, fatigue, and peril, the elegant bijouterie with which you are decked is torn from the deepest bed of the ocean!

III. THE PENNATULIDÆ, OR SEA-PEN.

This curious family received from Cuvier the name of _Swimming Polypi_, and from Lamarck that of _Floating Polypi_. The name of Pennatulæ, by which they are generally known, is taken from their resemblance to a quill, _penna_. In the words of Lamarck, "It seems as if Nature, in forming this composite animal, had wished to copy the external form of a bird's feather." Our fishermen call it the _cock's comb_, which is not inapt, but less expressive of its peculiarities. This animal is "from two to four inches in length, of a uniform purplish-red colour, except at the hip or base of the stalk, where it is pale orange-yellow; the skin is thickish, very tough, and of a curious structure, being composed of minute crystalline cylinders, densely arranged in straight lines, and held together by a tenacious glutinous matter, the cylinders being about six inches in diameter, in length straight and even, or sometimes slightly curved, and of a red colour, which communicates itself to the zoophyte." (Johnston.) The animals by which it is formed constitute colonies, which, however, are only attached to the rocks by an enlarged basis; it appears to live generally at the bottom of the sea; its root, if we can use the term, buried in the sands or mud; its polypiferous portion sallying out into the water. The agitation of the waves and the fishermen's nets often displace these aggregates of creation, and then they float at various depths in the bosom of the ocean.

The stalk of the polypidom is hollow in the centre, having a long slender bone-like substance, which is white, smooth, and square, but tapering at each extremity to a fine point. The polyps, which are fleshy and white, are provided with eight long retractile tentacula, beautifully ciliated on their inner edge with two series of short processes strengthened with crystalline spicula. The mouth in the centre of the tentacula is somewhat angular, bounded by a white ligament, a process from which encircles the base of each tentaculum, which thus seems to issue from an aperture. The ova lie between the membranes of the pinnæ; they are globular, of a yellowish colour, and by a little pressure can be made to pass through the mouth. The polyps are distributed with more or less regularity in such a manner that one of the extremities of the common axis is always naked: this part has been compared to the tubulous part of a feather. The stem, common to the colony, is a solid central axis, more or less developed, which is covered with a fleshy fibrous substance, susceptible of dilatation and contraction.

The _Pennatulidæ_ comprehend three genera; namely, those with polyps on bipinnate wings, having--according to Dr. Johnston--

Polypidoms plumose, in Pennatula. Polypidoms virgate, or wand-shaped Virgularia. Polypi, unilateral and sessile } Polypidom, linear-elongate. } Pavonaria.

In the genus _Pennatula_, the polyps are disposed in transverse rows upon the outer and inner edge, in a series of prolongations in the form of a feather. These winged species of polypidom are somewhat scythe-shaped, well developed, and furnished with a great quantity of pointed spiculæ, which are constituted of bundles at the base of the calyx. The space between the two rows of appendages is sometimes a tissue, sometimes scaly, sometimes granulous. Of the _Pennatula_ five species are known, and all of them appear to be gifted with phosphorescent properties. We may note among these species _Pennatula spinosa_ (Fig. 61), which inhabits the Mediterranean, and takes its name from its colour; _Pennatula phosphorea_, which abound in most European seas, being found in great plenty, clinging to the fishermen's lines round our own northern shores, more especially when they are baited with mussels.

_P. phosphorea_ is of a reddish purple, the base of the smooth stalk pale; the raches roughened with close-set papillæ, and furrowed down the middle; pinnæ close; polyp cilia uniserial, tubular, with spinous apertures. (Sibbald.)

Bohadsch says the _Pennatulæ_ swim by means of their pinnæ, which they use as fishes do their fins. Ellis says, "It is an animal that swims about in the sea, many of them having a muscular motion as they swim along;" these motions being effected, as he tells us in another place, by means of the pinnules or feather-like fins, "evidently designed by Nature to move the animal backward or forward in the sea." Cuvier tells us they have the power of moving by the contraction of the fleshy part of the polypidom, and also by the combined action of its polyps. Dr. Grant says, "A more singular and beautiful spectacle could scarcely be conceived than that of a deep purple _P. phosphorea_ with all its delicate transparent polypi expanded, and emitting their usual brilliant phosphorescent light, sailing through the still and dark abyss, by the regular and synchronous pulsations of the minute fringed arms of the whole polypi;" while Linnæus tells us that "the phosphorescent sea-pens which cover the bottom of the ocean cast so strong a light, that it is easy to count the fishes and worms of various kinds which sport among them."

Lamarck, Schweigger, and other naturalists, however, reasoning from what is known of other compound animals, deny the existence of this locomotive power in these zoophytes; "and there is little doubt," says Dr. Johnston, "that these authors are right, for, when placed in a basin of sea water, the _Pennatulæ_ are never observed to change their position; they remain in the same spot, and lie with the same side up or down, just as they have been placed. They inflate the body until it becomes to a considerable degree transparent, and only streaked with intercepted lines of red, which distend at one place and contract at another; they spread out the pinnæ, and the polyps expand their tentacula, but they never attempt to swim, or perform any process of locomotion."

_P. mirabilis_ is common in the east and north coasts of Scotland.

The _virgularias_ differ from the _pennatula_ chiefly in their development, relative to the axis of the colony and the shortness of the pinnæ, which carry the polyps; and in this, that no spiculæ enter into the composition of its softer parts. _V. mirabilis_ is found in the North Sea, on the coast of Scotland, and as far north as Norway. In Zetland it is known as the sea-rush. It is abundant in Belfast Lough, but, from its brittle nature, perfect specimens are difficult to obtain.

"It seems," says Sowerby, "to represent a quill stripped of its feathers. The base looks like a pen in this as in other species, swelling a little way from the end, and then tapering. The upper part is thicker, with alternate semicircular pectinated swellings, larger towards the middle, tapering upwards, and terminating in a thin bony substance, which passes through the whole extent, and is from six to ten inches in length."

In a communication to Dr. Johnston, from Mr. R. Patterson of Belfast, commenting on Müller's figure of _Virgularia_, he tells us that in the longest specimen he had, no two plumes were precisely alike--so unlike, indeed, that the artist copying one, could not for a moment hesitate, after raising her eyes from her paper, to look at the animal, as to which she was copying.

Its short waving and deeply dentated wings are of a brilliant yellow. The polyps, which appear upon their lobes, are whitish, transparent, and form a fringe of small diaphanous white stars (Figs. 62 and 63). We may figure to ourselves a slender wand-like and much-elongated polypidom, carrying only a non-contractile polyp on one side, which would give us an idea of the Pavonaria, of which we know only one species, which is from the Mediterranean.

_Virgularia mirabilis_ is undoubtedly one of the finest polypidoms found in the ocean. Two series of half-moon shaped wings, obliquely horizontal, are placed symmetrically round an upright axis. They embrace the stem somewhat in the manner termed _petiolate_ by botanists, clasping it alternately; or, shall we say, like two broad ribbons rolled round a stem in an inverse direction, in such a manner as to produce the effect of two opposing flights of stairs. These wings are waving, vandyked, and fringed on their outer edge, and of a brilliant yellow; the dentature of the fringe being the lodging of their pretty little polyps, which display occasionally their gaping mouths and expanded gills. The polyps are white and semi-transparent. When they display their rays, the margin of each wing presents an edging of silvery stars.

The _Umbellularia_ have a very long stem, supported by a bone (Fig. 64) of the same length, and terminated at the summit only by a cluster of polyps. They have been found in the Greenland and other northern seas.

The _Veretillum_, which inhabit the Mediterranean (Fig. 65), have a simple cylindrical body, without branchiæ, and a rudimentary polypidom, furnished with very large polyps of a whitish colour.

IV. THE ALCYONARIA PROPER.

The beings which compose this group have the fleshy polypidom always adherent, without axis or solid interior stem. They are divided into four families or tribes. One of these, the _Cornularia_, are zoophytes, and live in isolation, or gathered together in small numbers on the surface of a common membraniform expansion. The _Cornularia cornucopia_ live on the coast of Naples, _C. crassa_ on the Algerian coast. Other genera make their appearance on the coast of Scotland, of Norway, in the Red Sea, and in the Indian Ocean they appear in great numbers.

In the _Alcyonaria_, properly so called, the polypidom is very thick, of a semi-cartilaginous consistence, granular, and rough to the touch.

The genus _Alcyonium_ is numerous in species and widely dispersed. _A. digitatum_ is very common on our coasts, and on many parts of the coast scarcely a stone or shell is dredged up from deep water which does not serve as a support to some one or more species of _Alcyonium_. It is known by various popular names by our sea-side population, such as _cow's paps_, from its resemblance to the teats of the cow--_dead man's fingers_, from the occasional resemblance of its finger-like lobes to a man's fingers.

The polypidom is a simple obtuse process, the outer skin of which is tough and coriaceous, studded all over with star-like figures, which on examination are found to be divided into eight rays, indicating the number of the polyps enclosed in its transparent vesicular membrane. It is dotted with minute calcareous grains, and marked with eight longitudinal lines or septa, stretching between the membrane and the central stomach, which divide the intermediate space into an equal number of compartments. These lines not only extend to the base of the tentacula, but run across the anal disk, and terminate in a central mouth. The tentacula are short, obtuse, ciliate on the margins, and strengthened at their roots by numerous crystalline spiculæ. The polyp cells are oval, placed just under the skin, and are the terminating points of certain long canals which traverse the whole polypidom. The polyps, which are distributed over the whole surface, can withdraw into the cavities; they are, besides, of an extremely vital sensibility: the least shock impresses itself on the tentacula, the impulse of a wave even producing contraction; in response, the animal, which is well developed, sallies out perceptibly, but immediately retires again to hide itself in the cell.

We find on the coast, in the Channel, and in the North Sea, _Alcyonium digitatum_, the mass of which is of a reddish white, ferruginous, or orange; _A. stellatum_, found on the shores of the Mediterranean, is expanded in its upper part, narrow towards its base, very rough on the surface, and rose-coloured; _A. palmatum_, is cylindrical, branching at the summit, of a deep red, except at the base, where it is yellow: this is met with in the Mediterranean.

We may note as a type, altogether different from any yet touched upon, the _Nephtys_, in which the polypidom is a coriaceous tissue bristling with spiculæ over its whole surface. In _N. Chabroli_, the polypidom is squat, with thick spreading arms covered with lobiliform branches, the tubercular polypidom of which are columnar and obtuse, the sicula green, and the tentacula of the polyps yellow.

"On a cursory view," says Dr. Johnston, "the polypodium of the three families embraced appear very dissimilar, and accordingly, by many recent authors, they have been scattered over the class, and placed widely asunder. The affinity between them, however, is generally acknowledged, and had been distinctly perceived by some of the earliest zoophytologists. Thus Bohadsch found so much in common in the typical pennatulæ and a species of _Alcyonium_, that he has not hesitated to describe them as members of the same genus; and, although the more systematic character of Pallas prevented him from falling into this error, if error it can be called, he did not the less recognize the relationship between the genera or families. Pallas also tells us that his _Pennatula cynomorium_ differs from the _Alcyonium_ only in this, that the former is a movable and the latter a fixed polypidom; and he saw with equal clearness the connection which exists between these genera and the shrub-like _Gorgonia_. Of the _Pennatula mirabilis_ he had doubts whether it was not rather a species of _Gorgonia_, until he perceived that the stem was attenuated at each end, and free; and of the Sea-pens generally, Ellis remarks that they are 'a genus of zoophytes not far removed from the _Gorgonias_, on account of their polyp mouths, as well as having a bone in the inside and flesh without.' 'On the other hand, the _Gorgoniæ_ seem,' says Pallas, 'with the exception of their horny skeleton, to be nearly similar in structure to the _Alcyonia_; but as there are species of _Gorgonia_ which are suberose internally, and almost of a uniform medullary consistence, even this mark of distinction fails to separate the tribes, and we have little left to guide us in arranging these esculent species excepting their external habits.'"

"With most corallines," says Frédol, "the elementary individual, in spite of the adhesion established among them, possesses a vital energy all its own; it is in some respects quite independent. They have each its own particular will, which it is difficult to mistake for a common will; but it is not thus with the _Pennatula_. Their association consists of a non-adherent polyp, which moves--obscurely, it is true--but still it moves. To what does this lead? To this: that the parts which they possess in common, in place of being horny or calcareous--that is, completely inert--are fleshy, with contractile powers; that is to say, animated. Consequently, the polyp of the _Pennatula_ are less independent of each other than the coral polyp, which have a central, perhaps a sensible organ, common to all, which binds them to each other, giving a certain unity to their acts. The Coralline polyps have no will; the _Pennatula_ have."