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_.
[Illustration: Fig. 41. Tubipora musica (Linn.), half the natural size.]
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_.
[Illustration: Fig. 42. The Sea Fan, Gorgonia flabellum (Linn.).]
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.
[Illustration: Fig. 43. Fan Gorgon, magnified.]
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.
[Illustration: Fig. 44. Gorgonia verticellata (Pallas).]
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.
[Illustration: Fig. 45. Gorgonia verticellata (Pallas), magnified four
times.]
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_).
[Illustration: Fig. 46. Isis hippuris.]
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.
[Illustration: Fig. 47. Living Bed of Coral after the entrance of the
Polyps.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 48. Three Polyps of the Coral. (Lacaze-Duthiers.)]
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.
[Illustration: Fig. 49. Coral Polyp. (Lacaze-Duthiers.)]
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.
[Illustration: Fig. 50. Another form of the Coral Polyp.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 51. Coralline Spicula. (Lacaze-Duthiers.)]
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.
[Illustration: Fig. 52. Circulating Apparatus for the nutritive fluids
in the Coral. (Lacaze-Duthiers.)]
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.
[Illustration: Fig. 53. Section of a Branch of Coral.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 54. Birth of the Coralline Larvæ.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 55. Very young Polyps, attached to a Bryozoa.]
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.
[Illustration: Fig. 56. A young Coral Polyp fixed upon a Rock.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 57. Young Coral Polyp attached to a Rock and
expanded. (Lacaze-Duthiers.)]
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.
[Illustration: Fig. 58. A Rock covered with young Polyps and Polypidom.
(Lacaze-Duthiers.)]
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.
[Illustration: Fig. 59. Corpuscles from which originate the Polypidom.]
[Illustration: Fig. 60. First form of the Polypidom. (Lacaze-Duthiers.)]
"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.
[Illustration: Plate III.--Coral Fishing on the Coast of Sicily.]
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."
[Illustration: Fig. 61. Sea-pen, Pennatula spinosa. (Edes.)]
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.
[Illustration: Fig. 62. Loose-winged Virgularia, Virgularia mirabilis
(Lamarck).]
[Illustration: Fig. 63. Branch of Virgularia, enlarged.]
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.
[Illustration: Fig. 64. Umbellularia Greculandrea (Lamarck).]
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.
[Illustration: Fig. 65. Veretillum cynomorium (Lamarck).]
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."