Popular Science Monthly/Volume 31/October 1887/The Oldest Noble of Them All
|THE OLDEST NOBLE OF THEM ALL.|
WE sailed out from the little port of Alleghero, on the northwest coast of Sardinia, on a clear morning, with a bright sun, light breeze, and a moderate flow of tide, to the nearest coral banks. Our fishing-apparatus consisted of a large wooden cross-drag weighted with lead, to which ropes and nets were attached, which was to be painfully hauled over the bottom of the sea at a depth of from one hundred to two hundred metres, to gather what it could catch of the life abiding in those regions. The success of the operation depends largely on the skill and discrimination of the padrone. Two sailors and a youth manage the very primitive capstan by which the rope, that the padrone holds in his hand, is unrolled. He knows, by feeling the movements of the rope, its tension, sliding, and jerking, whether the drag is passing over sand, mud, hard ground, or solid, jagged rock. At times the youth stands alone at the capstan, and the sailors take the rudder in hand and turn the vessel as the padrone directs. Sometimes they have to work with all their might, as when the apparatus gets fastened or is drawn under overhanging rocks. There are a thousand accidents to be guarded against, and they frequently end in the loss of the drag.
Thus the sea-bottom is swept for a few hours as with a broom. The cords of the drag sling themselves around everything that projects and is movable; large pieces of rock are ensnared and torn loose with all that is upon them. Whatever creeps upon the ground is made fast.
The padrone orders a halt, and the sailors apply themselves to the capstan to draw in the rope. It is a task calling for the exertion of their full strength to dislodge the apparatus and pull it up with the heavy load which it has collected. Sometimes the leverage of the sea-waves is invoked. The capstan is locked, the rope is stretched to its utmost, and the bark is set by a few motions of the rudder upon the crest of a rising wave. The reaction, when the machine is dislodged, is often so strong as to threaten to overturn the bark. A cloud of slime announces the approach of the apparatus to the surface. The drag is pulled out and laid upon the ship's edge, and the nets which are swimming around are drawn in and thrown into the inner space. Capstan and helm are deserted, and the sail is drawn in. The men squat in a ring around the net, and pick out with their fingers the objects that are entangled in it, and sometimes the knife has to be used to solve some unusual complication. I had filled my pail with clear sea-water before the apparatus was drawn up. I had given orders, which were very difficult to get executed, to have nothing cast overboard, so great was the temptation to the men to judge this or that piece of coral worthless and throw it away. After taking a lunch, I took out my instruments which I had provided for the occasion, and made a careful examination of the stones, to see what life might be upon them, scrutinizing every cavity and crevice closely with the lens. At last I found the particular object of which I was in search. It was a little shell about the size and thickness of a lentil, which had grown fast to the stone by a piece of its edge. It was of a dingy, brownish color, with a dim red spot in the middle, and was so covered with slime and mud that it could hardly be distinguished from a stone-splinter. I loosened it with a knife and exhibited it to the boatmen on the palm of my hand. "Look at it sharply," I said, "so that you will be able to recognize it anywhere, and then help me to look for more." In the course of half an hour every stone had been examined, and three or four shells had been obtained, among them a larger one, yellowish-green and three-cornered, which was attached by the tip. "Your Excellency," said one of the sailors, "are there no such shells in the country you came from?" "In Switzerland?" I replied. "No. These shells grow only in the sea, and there is no sea in Switzerland." "That is a good way from here, and the journey must have cost a great deal of money. We are very simple people, your Excellency, and must believe you; but we can not understand why you should have come so far and spent so much money just to get two or three poor little shells that are not worth any money." "But I tell you it is worth a great deal to me to see these shells living." " But you can't sell the shells and get your money back again? " "Certainly not, but I have another kind of interest in them." "We believe, indeed, that something else must be hidden behind this, and that is what we should like to know; but it does not concern us any further. We give you the shells because you have paid us for them, and wash our hands in innocence. You are responsible for what else is done with them; but a prudent man does not act as you do. Don't consider it wrong in us, your Excellency. We should like to earn enough in this business to devote a candle to the Madonna of Valverde, with which we may atone for our sins, and the Madonna will pardon us if we have helped on a little foolery or witchcraft to earn a little money by it."
It had come to this, then, that I was a fool or a wizard. I should clearly have to give some explanation of my business to these men; but it would be impossible to make their simple heads take the conception of science or of scientific interest. So I was obliged to make up a little fiction or allegory with which to put them off, and I told them that I wanted the shells to settle a wager. I had been present at a discussion, I said, a long time ago, in the company of Prince Humbert (now king), as to which were the oldest noble families on the earth. Some were of the opinion that they were to be found in this nation and some in that, when I interfered and said that I knew of a much older nobility than any that they had brought forward—of one that was present at the creation of the world. The crown-prince, intimating that my mere assertion could not carry the day, invited me to produce a living shoot of that old stock. I told him that I would do so if I were given time, and he granted me as long an indulgence as I desired. Some years had passed since my promise was made; but now I desired to fulfill it, and had come to this place to get the living shoots of the oldest family on the earth. What I had asserted was the simple truth. The ancestors of these shells have lived in the sea ever since there was a sea, "and now I shall take these living muscles to the king and tell him that I have won the bet."
Let us look now at the little company which is collected here on a stone, and whose individual members are found in the Mediterranean Sea. The largest of the specimens on the right side of the drawing,
which has grown by a short stalk to a small coral-stem, represents a smooth shell, of glassy clearness, and hard as glass. Linnæus was acquainted with it, and called it Terebratula vitrea, or the glassy terebratula. Another much smaller kind, whose white, three-cornered shells are neatly furrowed in the direction of their length, is supposed to have a kind of resemblance which I have never been able to find, with a snake's head, and is named in the classification Terebratulina caput serpentis. Two specimens can be seen in the drawing, one in the right-hand lower corner of the stone, on the surface; the other on top near the middle, in profile. On the Sardinian coast this species wears a yellowish-green coat, which consists of a slime sticking fast to the shell with sand-grains. I thought at first that I had discovered a new species, and would be able to perpetuate my name in the zoölogical registers till the end of science, by giving it to this creature, when my zeal unluckily prompted me to take hold of the soft coat with a pincers. The tool drew off the envelope and under it shone the ivory-white shell. Besides these two species belonging to the family of the Terebratulæ, there are two smaller shells on the stone. The smallest species, of which three specimens lie on the middle of the stone, has the form of a heart, which is attached by its point. It shows a few dull-red spots on the middle of the shell, and is named Argiope. The other one, a little larger species, appears at the left in three specimens, with a straight hinge-border, and is broad and firm, and is called Megerlea.
We placed this piece of stone with its four species of shells, to which others that abound in the Mediterranean might be added, into a pail filled with sea-water, in which several other animals were stirring. We intended to watch the life-expressions of these fixed animals. Our patience was exposed to a hard trial. Hours passed away, without our being able to perceive the slightest movement. We had become tired and were yawning, when we thought we perceived the little Argiope mocking us. It was, in fact, gaping. The Megerlea, the snake-head terebratula, and the glass terebratula, followed its example and yawned too, but as discreetly as if they were in well-bred society. The valves parted from one another only a little; a few fine, glassy, glistening hairs, which could only be seen with the glass, appeared outside. That was all. Terebratulas have been kept for weeks and months living in glass vessels filled with sea-water, without any other movement being perceived than this gaping, which sometimes continued for hours. When they had gaped enough, they shut their shells, slowly and measuredly, as if they would sleep; and, when they had slept enough, they gaped again. Old noble by entail, which has grown fast to its estate, and sleeps or gaps its life away! But what do they feed upon? A closer investigation was required to find that out.
The two valves of the shell are not alike. The difference is greatest in the terebratula. One valve is wide, bellied, and runs into an upward-turned beak perforated by a round hole through which passes a short, round stem that is resolved outside of the shell into a bundle of thongs by which the animal fastens itself. The smaller valve rests as a cover upon this one.
We try to open the valves as they are opened in the gaping, but it is impossible to do it without force; so we have to break the shell open. Fig. 2 shows the opened snake-head terebratula magnified six times. The bellied valve is filled with two peculiar, half-moon-shaped processes, consisting of two bent, cartilaginous pipes, on the outer side of which stand a number of fringes which wind in a worm-fashion and circulate in constant movement. The space between these great arms, as they are called, includes two smaller arms, provided with similar fringes, which roll up helicoidally toward the bottom. Nearly all the space of the bellied shell is occupied by these forms; except that above, toward the point of the valve, may be seen some muscles, which open and shut the shell, and conceal from view the very small body proper. In this may be found a short bowel with a large liver, the nervous system, and, perhaps, also the heart. The bowel has a real mouth only at the junction of the two arms, but is Fig. 2.—Anatomy of a Brachiopod. entirely closed at the other end. The inner surface of the valve is covered with a fine, transparent skin, which is called the mantle, in the somewhat thickened border of which are planted the stiff, transparent bristles, which are moved back and forth by the contraction of the membrane in which they are fixed. The organs of generation also lie in the mantle, and are shown in the drawing as two lumps in the raised back valve. Thus, small is the body in proportion to the vigorously developed arms, from which the name of the whole class, brachiopods, is derived. But are they really arms? They are hardly movable. If we stick a needle into one of them, it does not stir; and there are species in which they are completely calcified. Only the fringes move and respond immediately to excitations.
We cut off a piece of the arm and place it under the microscope. Each fringelet is a tube made of a firm, elastic membrane, in the hollow of which are laid one or two bundles of fibers of a muscular or nervous character. On the outside the tubes are clothed with delicate cells connected into a texture bearing fine, actively vibrating ciliæ. These ciliæ generate a bubbling stream in which dance the minute bodies that are floating in the sea-water. The whole stream, which the ciliæ of the thousands and thousands of tubes produce, flows from the periphery toward the mouth. The little tubes all open into the chief pipe of the arm, and are, like that vessel, filled with fluid.
With this observation a considerable number of functions are explained at the same time. The fluid in the little tubes and the chief pipe doubtless plays a part in the movements, in that it is at times pressed into the smaller vessels and expands them, and at other times is held back by the foldings and contractions brought about by the muscles in the chief pipe of the arm. But the constant stream which the ciliæ keep up is all the time bringing new particles of water, heavily charged with oxygen, in contact with the inner surface of the mantle. An exchange of gases through their thin walls is certain to arise; the stream also produces a respiration, which is simply an exchange of the carbonic acid generated within the tissues of the body for the oxygen that is held in the water. The stream also whirls minute bodies, microscopic animals and plants, to the mouth, which swallows them. Our terebratula has no other means of getting food. As the oyster and the rotifer are fed by the streams and whirlpools produced by the ciliæ, so also is the terebratula. When the shell is closed, only the exchange of gases takes place; but when it is opened, or when the animal is gaping, it is eating, for these larger bodies are drawn in through the whirling. That this really takes place is shown by the contents of the stomach, in which we may observe undigested remains, the silicious shells of plants, diatoms, or Radiolariæ, and the needles of fungoids. The organic substance is digested and dissolved in the stomach, while the undigested remains are expelled through the mouth. Sea-water, especially near the ground, to which the terebratulæ are attached, swarms with shell-protected and naked matter of this kind. The terebratula is, moreover, in the happy situation of having nothing to do but spit out the shells, for the meat itself flies into its mouth.
Every fixed animal produces moving young. Were this not the case, the animals could not be distributed into spaces beyond their immediate abode. Very curious young are produced from the eggs of our arm-foots, which do not at first resemble their parents at all; larvæ that swim around in freedom, having eyes, and armed with bristles. They so much resemble the larva of some of the ringed worms, that one would be apt to suppose at first sight that they were of that kind. But after a time of wandering they settle themselves down, and there then takes place, with the formation of the shell, a retrograde metamorphosis, by which the animal is gradually brought back to its definite form. It is therefore easy to conceive that our arm-foot leads a very safe life, and that, protected as much as possible against enemies and other dangers, it can spin out its existence as long as the sea does not dry up. Of course, in their younger days, the wandering larvæ may be swallowed up in numbers by other animals, but when the young brachiopod is once fixed, the shell, the mantle-edge with its bristles, and the ciliary apparatus protect it so well, that not even parasites can attack it. Although fungoids, other animals, and occasionally fellow-beings of its own race may establish themselves on the outside of its shell, and load it to a certain extent, but otherwise do it no harm, no parasite has ever been seen within. The little wart that appears on the glass terebratula in the picture is one of their young. There have always been fishes which, after a fashion, eat corals and crush them with their hard teeth, to digest the polyps which the corals contain, and expel the lime-substance; but I hardly think they would take in the arm-foots, whose bodily substance is so stringy and yields so little nourishment. In the deep sea, also, the animals are thoroughly protected against the sudden changes of temperature which animals living in shallow waters and near the shores have to encounter.
I now come to my oldest noble. It is an established fact that in the most ancient strata in which fossil remains have been found, in the system called Cambrian, in the primordial fauna, shells occur which differ but little from the living arm-foots of to-day. These older or palæozoic strata fairly swarm with arm-foots; many rocks are entirely made up of them, and the richness of their forms is inexhaustible. From these earliest ages on, the animal creation gradually assumed more definite shape as the number of individual arm-foots diminished. Doubtless the more perfectly-formed organism superseded the others in the struggle for existence. The noble who relies for the support of his position only on the age of his race-stock, must die out at last if he can not adapt himself by a further development to the demands of the new time. This the arm-foots could not do: they show no progress Fig. 3.—The Lingula. toward a higher stage of organization. The comparatively rare brachiopods of our seas are therefore only the scanty relics of departed glory, isolated survivals of a type that was formerly wide-spread and numerous in all the seas. But it is wonderful that a race-shape should have maintained itself quite unchanged through all the geological epochs to our own time!
At shallow places in southern seas, there creep a kind of brachiopods in the sand whose shaping is rather like that of a worm than of a brachiopod. It is called the Lingula, or tongue-mussel (Fig. 3.). This creature has an even, somewhat horny shell, and a relatively long and thick stem which is clothed within by a tough layer of muscle. Along with the other species of its kind, it is distinguished from the rest of the family by the shell having no closure, while the bowel, after many turns within the body, opens without. As the valves of the shell only cover the animal, but are not closed tight, they can be easily opened and also moved sidewise upon one another. The animal is never fixed. This is the oldest animal form of the present existing creation. Lingula-shells appear in the Cambrian strata, and have been found in all the geological systems. So far as it is possible to judge from the shells, the genus has propagated itself unchanged through all the earth-history of organisms, has survived all revolutions, and has only varied into a few species differing but little from one another.
In the Silurian strata immediately following these, in which so far nearly two thousand species of arm-foots have been found, are two other still living genera: the one, Discinisca, without closure, but furnished with a muscular stalk; the other, Rhynconella, having a shell-closure and a fibrous, but not further contractible, stem. Most of the genera living to-day can boast of a high age. Terebratula traces its race-stock back to the Devonian system, as does also Crania, while Argiope, Megerlea, and Terebratulina derive their ancestors from the Jurassic.
Our oldest vertebrate is a rare fish called Ceratodus, which lives in some of the Australian rivers. It has a few relatives living in the rivers and marshes of Central Africa and South America, and is adapted to breathe in the air through lungs and in the water through gills. Teeth of species of Ceratodus, clearly recognizable by their peculiar formation, appear in the muschelkalk of Würtemberg and Central Europe. Old as the race of the Ceratodus may be, it can not compare with that of the primeval genus Lingula.
I told my coral-fishers a falsehood in my story of the bet, but, as in every fiction there is a grain of truth, there is in this one the fact of the existence, in the present animal world, of a family of extremely anciently descended nobles, whose ancestors were members of the first animal creation visible to our eyes. — Translated for the Popular Science Monthly from Ueber Land und Meer.