Popular Science Monthly/Volume 6/November 1874/The Natural History of the Oyster I
|THE NATURAL HISTORY OF THE OYSTER|
AN illiterate fisherman once became wellnigh eloquent in his effort to describe to us the treasures which the waters offered freely to man. Nature is, indeed, lavishly opulent. Among the food-treasures of this bounteous harvest of the sea, the oyster ranks high in the general esteem. And deservedly so, for she is truly the queen of the bivalves. Let us try to tell the story of her life.
Oyster-planting.—For a creature of such lowly rank in the scale of animate being, it is wonderful what a literature attaches to the oyster. Through the roll of the ages it has been a factor of prime importance in the convivial instincts, the moralities, and the industries of men. It has honorable mention in classic song and story. When imperial Rome had her many million populace, and her almost fabulous wealth, the oyster figured prominently in the more than lavish luxury of that extravagant city. Do our oyster-growers know how ancient their calling is? About 2,400 years ago one Sergius Orata, a man of a practical mind, turned Lake Avernus into an oyster-bed; and through his culture of this bivalve the Lucrin oysters, as they were called, became in reputation the "Saddle-Rocks" of Rome. And what a splendid market he had! His practical genius carried the new industry of oyster-planting to great perfection; and such was his reputation in that line that the Romans had a saying that, should the oysters stop growing in Lucrin Lake, Sergius would make them grow on the tops of the houses. Avernus has at last succumbed to the mutations of time, and is to-day a miserable hole of volcanic mud. It now offers a good opportunity to test the great man's abilities; but Sergius Orata himself "dried up" some time ago.
Near Baiæ and Curiæ is the Neapolitan Lake Fusaro (Fig. 1). This was the classic Acheron. It is about three leagues round, and is hardly
in any part more than six feet deep. Its bed is a black volcanic slime, such as one might suppose would be death to mollusks generally. From time beyond memory this has been an oyster park or plantation; a place for raising the young oysters, that is, the oyster-seed—namely, the small oysters, which, when put in proper places, will become oysters of an eatable size. For these young to settle on, heaps of stone are placed in the lake with a circle of piles round each heap (Fig. 3). In other parts of the lake the piles are driven in rows and connected by ropes, from which hang fagots, on which also the young can fix themselves (Fig. 4). These fagots, at the proper time, are easily pulled up, and the young, or "seed," picked off by hand to be planted elsewhere.
Formerly France possessed a great abundance of native oysters. But this industry was without regulation, and the French natives, like our Northern natives, came near being exterminated. A few years ago Prof. Coste, of the French Academy, called attention to the fact that the French oyster was becoming extinct. He took up the study of this mollusk in earnest, and learned many important facts concerning its nature. He even went to the Neapolitan oyster-park, and observed how the fishermen there saved the young ones. He then appealed to the government, which put means in his way for experimenting, and, in a short time, he had a successful oyster-plantation under way. It is in France as elsewhere, "seeing is believing," and "there is nothing that succeeds like success." Under the wise direction of this learned naturalist the new industry, oyster-planting, became a furor in France. "In two years 1,200 capitalists, associated with a similar number of fishermen, occupied a surface of 988 acres." By which is meant the area of shore-line exposed at low tide. And what labor! so thorough and scientific. The isle of Ré, with its unsuitable, muddy shores, had all that sea-bottom altered. In two years twelve miles of sea-coast thus changed was planted, with 1,200 parks in operation, and thousands more projected. Now, oyster-culture is conducted in France on better principles than anywhere else. And all of this great additional wealth to the nation comes out of the applied science of a man "that studied shells and worms," as is often said in derision. In France scrupulous provision is made for husbanding the fry. In America no effort is made in this direction, and the time is not far off when the nation will wake up to a serious calamity in this respect.
The American practice is simply this: In the spring of the year large numbers of sloops and schooners go south to procure the young oysters called "seed." This sets considerable money afloat southward, as they have to take with them the ready cash. In the days of "wild-cat" banking, the Southrons would take nothing but specie, and that must be paid just so soon as the oysters were put into the boat. The "seed" is obtained chiefly in the Rappahannock, the Nanticoke, and a few other places. Oysters also of a moderate size are often brought north and laid down for a season, that they may increase in size and acquire something of the flavor of the Northern native, so superior to that of the Southern. The better kinds of the Southern, such as the Lynn Haven Bays, Sandy Points, Cherrystones, York Rivers, etc., are sent for immediate consumption to Baltimore, Washington, Philadelphia, and some to New York. New Jersey,
New York, and Connecticut, are the favorite planting-grounds. When the vessels return with the young oysters they are planted, that is, scattered over the beds. As the lower side of the oyster is the heavier, this generally secures its falling right side up. The seed, or young oyster, is allowed to lie for from one to two years, seldom three, when it is considered ready for market, and in that time it has greatly improved in quality. Early in the fall the work of taking up the crop begins. This is done by what is called tonging. An instrument is used called oyster-tongs. Something of an idea of it may be got by supposing two garden-rakes with very long handles, with the tooth-side of each rake facing each other; let the handles be secured by a loose rivet about two or three feet from the teeth, so that by operating the extreme ends of the handles the whole contrivance shall act as a pair of tongs. Working over the side of his boat, the oysterman and his comrade thus take up the first of the harvest. After tonging,
the bed is again gone over, but this time with the dredge (Fig. 5). In this process a vessel with sails must be used (Fig. 6). The great iron bag or dredge is cast into the water and dragged along the bottom. Then (and terrible hard work this is) it is drawn up, and its contents are emptied on deck. Whether tonging or dredging, oystering requires broad-chested men, with sturdy hands and arms. The oysters are next taken a little way up a fresh-water creek or stream, into which they are thrown "to get a drink." The process sweetens and cleanses them. One day, often even one tide, is enough for this purpose. As the water is not deep, the mollusks are taken up with large forks. The workmen stand in the stream, wearing very high rubber boots. When late in the fall, this is intensely cold work. Before being thrown into the fresh water, a sorting process is gone through. There are dead oysters, and winkles, and conchs, and stones, and many useless matters, to be separated. All this is thrown upon the banks of the stream. After being taken out of the stream, before they can be sent to the great city, comes the process called "culling," that is, assorting into the sizes known in the trade. The smallest are called "culls," and are sold by the bushel. These are used in making the popular "stews" of the saloons; also, when opened, it is this sort that is sold by the quart for domestic use. The others are known as "count," and the restaurants serve them up as "fries," and on the half-shell, as raw. These are sold by the hundred.
After the harvest is finished, not a few oysters will yet remain on the beds. The grounds are then given up to the laborers who have worked them on hire. Under a new impulse these men go over the grounds again with tongs and dredge. They work on shares usually, returning to the owner of the beds one-half of the results, which makes a really handsome thing for the gleaners, whose work in this way lasts from two to three weeks, making three or four days a week, each man often clearing as his portion from four to five dollars a day. At any rate, such generally is the practice with its results at Keyport, N. J., where for many years the principle of the good old biblical rule, of not forgetting the gleaners, is almost religiously observed in the last gathering of this harvest of the sea.
local varieties.—It is generally conceded that the Northern oyster is superior to the Southern. Upon this understanding, and the fact that formerly the Southern oysters that were brought north were chiefly procured from Chesapeake Bay, and the favorite Northern natives were got around and near New York, the old oystermen used to speak in general terms of two kinds, the Southern and the Northern, which they designated as "Chesapeakes" and "York Bays." There are, however, a great many local names, which are supposed to indicate special excellences. All these northern edible oysters are of one species, Ostrea borealis. Some naturalists, however, claim that the Southern is different, and should be called Ostrea Virginiana. But for the plain reason that both varieties can any day be found in any oyster-bed in Long Island Sound, and indeed they seem to change by growth indiscriminately into each, a more rigid science would refer them all to the name given by Lister—Ostrea Virginiana. Yet, take them in the mass, and any experienced oysterman will tell the Southern from the Northern. The European oyster is called Ostrea edulis; but that it is sufficiently different to make a distinct species is far from certain. Experienced dealers will pick out the local varieties of the Northern article. Of these we have many names—such as the Keyport, City Island, Guilford, Blue Point, Rockaway, Saddle-Rock, Shrewsbury, etc. The Blue Point was for fifty years "the Knicker-bocker among oysters." It was raised chiefly in Great South Bay. This fine oyster had to yield on the appearance of the splendid Saddle-Rocks. This name is still given to all very large oysters, and generally to those taken in the East River. It is, however, no longer in existence. They were first brought to Fulton Market, New York, by an old negro named Henry Scott. The following, by our friend Dr. O. R. Willis, is authentic. It appeared in the New York Observer:
"The original Saddle-Rock oyster was not only very large, but possessed a peculiar, delicious flavor, which gave it its reputation. And it received its name because it was discovered near a rock known as Saddle-Rock. A high northwest wind, continued for several successive days, always causes very low tides in Long Island Sound and its bays. On the farm of David Allen, situated near the head of Great Neck, on the eastern shore of Little Neck Bay, is a rock about twenty feet high, and from fifteen to twenty feet in diameter. The shape of the top of this rock resembles somewhat the form of a saddle, and from that circumstance is called Saddle-Rock. At low water the upper or land side of this rock is left bare, while the opposite or lower side is in the water. In the autumn of 1827, after a strong northwest wind had been blowing for three days, a very low tide occurred, and the water retreated far below the rock, leaving a space wide enough for a team of oxen to pass quite around it. This extraordinary low tide revealed a bed of oysters just below the rock. The oysters were very large, and possessed the most delicate flavor;
we collected cartloads of them, and placed them in our mill-pond (tide-mill). The news of the discovery spread among the oystermen, and boat-loads soon found their way to the city, where, on account of their excellent flavor, they commanded fancy prices, even reaching ten dollars a hundred!—an enormous price for those days. In a very short time the locality was exhausted, and for more than forty years there has not been a real Saddle-Rock oyster in the market."
At present the favorite native is the Shrewsbury, which is mainly obtained by planting, in the Shrewsbury River, seed procured from Tappan Bay. Of this seed there will be in a bushel about 2,500 young oysters, costing about 60 cents. After two years' growth, 200 will fill that measure. At present the Shrewsbury is accounted by many as the emperor of the bivalves, and will fetch in market at wholesale from $1.50 to $3.50 a hundred. What is called the summer oyster is brought from the York and James Rivers, Va., and planted north late in the season for summer use. Some are brought from the waters of Maryland.
The Oyster-Trade.—Dragon, as it used to be called, Fair Haven now, near New Haven, was formerly the place where oysters were put up for Northern and Western use. The bivalves were opened and put into neat little kegs. Latterly the business has gone down to Baltimore. "Shipping is yearly becoming more extensive, and Baltimore—though ahead at present—has a powerful rival in the metropolis, as all roads lead to it, like those of the ancient world to Rome. In October the shipping to Europe and California commences, and latterly tubs instead of sealed cans are used. In shipping to St. Louis, Cincinnati, and other places within a distance of a thousand miles, oysters are shipped in cold weather in kegs protected by gunny-bags, but in summer the kegs are placed in larger vessels and the space packed with ice and sawdust. So expert has experience rendered the shipper that oysters seldom spoil, and the Western purchaser may rejoice in a comparatively fresh and wholesome article."
Even in the northern parts of the State of New York, thirty years ago, oysters were an unknown luxury. But the rapid transit "which has been developed in the last quarter of a century has given a great impulse to exportation, and statistics from reliable sources show that many millions of dollars' worth of oysters are yearly sent from this port alone. For instance, the average retail trade per week of Fulton Market requires 250,000 oysters, and one establishment is called upon to supply from 1,000 to 1,500 customers daily. The wholesale department packs and exports 100,000 weekly, and gives employment to a large number of men.
"The yearly returns from the home-market amount to $4,000,000 per annum, and from other localities to about $1,000,000. The trade gives employment to 2,500 men in New York City, and to 200 in Brooklyn. There are 750 oyster-saloons in the metropolis, and 100 in the City of Churches. On the North and East Rivers about 50 scows are employed receiving oysters from the vessels arriving from these various bays, and from these boats about 3,000,000 oysters are daily shipped throughout the country. Five hundred sailing-vessels are employed in this vicinity, which number includes every thing from a sail-boat to a schooner of 150 tons. A corps of 5,000 men is engaged in planting and bringing to market, who earn on an average from three to four dollars per day. In fact, it may be safely estimated that about 10,000 men, directly or indirectly, make a living in the oyster-trade of the two cities. Many of the ancestors of the wealthiest Knickerbocker families were oystermen, and at the present day many a bluff, rugged-looking man engaged in this business has a bank account that more pretentious people, living in a brown-stone house, might well envy."
American oysters are now being shipped to Europe by steamer. The first ventures proved disastrous. They were shipped in bulk in the vessel's hold. They "spoiled," that is, perished, doubtless from the warmth and want of air, as oysters are often carried by sail-vessels from the South to the North safely, although they may be longer on the way than the steamer, and even carry larger quantities in bulk. These vessels employed by the oystermen carry, according to the vessel's capacity, from 1,800 to 2,800 tubs, a tub being a bushel and a half. But, though oysters were at first lost in their transit by steamer, they now go more safely, being put up in barrels, instead of in bulk. And this business of oyster transportation is destined to assume immense proportions; hence the following from the World of December 22, 1873, may become an item in history: "N. B. Mulliner, A. W. Mead, Oliver Charlick, and Miles Smith have formed a company for the shipment of oysters to the London market, and made their first consignment during the past week from Freeport. It is proposed to sell the oysters on commission."
An experiment, the results of which, if successful, will be followed by great consequences, is a recent attempt made to acclimatize the New Jersey oyster in California. Joseph Ellsworth, a heavy operator in this bivalve, who owns one of those floating establishments known as scows, affairs of immensely greater importance than the name would imply, made a very interesting venture last fall. He freighted a car with the "seed" for San Francisco. The seed was obtained in Newark Bay, and 60 cents per bushel were given for it in the rough, that is, as it adhered to shells, etc. The best and cleanest were selected, averaging in size about that of the old copper cent. The cost of this seed would be about $8 per bushel at its delivery in San Francisco. It is estimated that two years' growth will suffice for this market, where they will be more easily suited on the question of size than the people East. It is also expected that, after the spawning-season is safely passed over, enough stock, or seed, will be had to make future operations successful. Of course, the whole matter is, as yet, an experiment. The native Californian oyster is a puny affair, and it is to be feared that the Eastern oyster will degenerate in Pacific waters. We shall see. Meanwhile the experimenter deserves great praise for the energy shown in his bold venture.
the risks.—It will be news to many to hear that the business of the oyster-producer is one of great risk. All is not gain to these industrious people, for often capital is sunk in the waters that is never taken up. Many years ago we remember the then small village of Keyport suffering a loss in one season of $50,000. Even a severe storm continued unusually long has smothered the beds by agitation of the mud, for the oyster must keep its nib out of the bottom. But two seasons ago, in one of the branches of Shrewsbury River, a crop was almost entirely lost, the supposition being that it was poisoned by the washing from a new turnpike, in the construction of which a peculiar ferruginous earth had been used. Formerly the oyster throve as a native as high up the North River as Peekskill, and probably its limit was not below fifty miles from the mouth of the river. They are now, however, exceedingly scarce, even as high as Croton. The belief exists that the railroad has destroyed them by the washing from the necessary working of the road, which is constantly finding its way to the river-bed. So long ago as 1851, Colonel John P. Cruger, of Cruger's Landing, a very intelligent observer, called our attention to the fact of the mischief thus done.
And there are meteoric causes which affect the oyster. We have known an unusually severe winter to kill the bivalves in great numbers. And even the seed in its transport from Virginia has been destroyed—whole valuable cargoes—by foggy weather, and adverse winds. Moreover, as will be seen, the oyster has its deadly enemies in the animate ranks.
The Physiology of the Oyster.—By persons engaged in the business, we have been asked, "Are there hes and shes among the oysters?" The answer of the naturalist would be, "There are not." Low down in the scale of life many animals on their sexual side are singularly suggestive of plants. Take, for example, that splendid grass, Zea mays—Indian-corn. On the top of this graceful plant is a large, brush-like panicle. This contains the staminate or male flowers. Embedded in the green cob of the ear are the pistillate or female flowers. Their pistils make the tassel, which is called "the silk." Upon these falls the fertilizing pollen of the stamens from the raceme above. Without this contact there would be no kernels on the cob. In some plants this bisexuality occurs in the same flower. A notable instance is that of the prolific strawberry known as Wilson's Albany Seedling. A similar fact, certainly an analogous one, is true of the oyster. It is bisexual. It is not masculine alone, nor feminine alone, but both; and perhaps might be defined by that innovation in modern grammar, as of "the common gender." It is hermaphroditic.
The question of the parental relation of the young oyster on its paternal side is most certainly a very perplexing one; for, albeit no matrimonial dereliction was ever known among these Ostreæ, yet the fact remains that no oyster was ever begotten that knew its own father.
If, now, the reader will take a little pains to compare our description of the organism of the oyster with Fig. 7, he will see that, however lowly the oyster may be regarded, it has a compact and even a complex anatomical structure, manifestly a beautiful adaptation to the creature's necessities; and even exhibiting, in a very instructive manner, a wonderful likeness to our own organization. If this seems a startling position, let the reader follow the discussion, and see if it be not made good. If we take an oyster in the hand, it will be observed that, of the two valves or shells, one is much deeper and heavier than the other. This is the bottom or lower valve, because, when lying undisturbed on the bed of the water, it is the under side. The upper valve is often a mere thin plate of shell. It is observable, too, that generally the lower valve is, on the outside, quite convex, while the upper one is usually either flat or a little concave. Let it now be remembered that, anatomically, an oyster has also two sides, and that while living its normal position is to lie on its left side. The valve, then, represented by the cut, is the lower or deep valve, in popular speech, but in scientific phrase it is the left valve. The oyster itself is shown as representing what is popularly known as its upper side, the side seen when eaten on "the half-shell;" correctly speaking, it is the right side of the animal.
Let us now follow the index-words of the figure. We find a thin sheet of flesh lying on the shell. It is the left mantle, for there are two, one to cover the right side also, so that both together are continuous as one, and with it the animal inwraps itself.The figure shows a portion of the right or upper lobe of the mantle. It is sometimes called the pallium, and really is the oyster's cloak, though it is always and only worn in the house. This is not true, however, of all the mollusca. The beautiful cowries, so high colored and bright, are exceptions. If you examine a common tiger
cowry or Cypræa, if an adult shell, you will find that, while the entire shell is covered with a shining enamel, there is along the whole length of the back of the shell "a line of pale color." The animal extends both folds of the mantle outside of itself and over the shell, and that line is where the lips of the folds meet. This mantle has much to do with obtaining food. The oyster opens its shells about a quarter of an inch apart. These membranes, that make the mantles from both sides of the animal, meet just at the opening of the shell. They are fringed at their edges with rows of tiny cilia, or soft fleshy hairs of extreme delicacy. This pallial fringe in an eminent degree serves the oyster as organs of touch. Probably this sense, though distributed somewhat over the entire surface of the body, is along this fringe exquisitely acute. The English call this fringe the oyster's beard. It is protruded just a little out of the shell; and these cilia, almost numberless, keeping up their rapid movements in the water, make as it were two parallel vibrating curves, which beget a sort of aquatic vacuum inside the shell, into which the water flows, as in a diminutive whirlpool. The stream thus affected brings with it the algae spores and animalcules which constitute the oyster's food. But where is the oyster's mouth? Speaking popularly, it is away back near the hinge of the shell, as shown in the cut. To this point the current flows. Now, it must not be supposed that all is fish that comes to the oyster's net. Far from it. Hence this mollusk has eclectic functions. Doubtless a sharp spicule of a sponge may occasionally get into the mouth, even as a bone splinter can get by accident into a human throat. The word "tentacles," in the cut, refers to certain organs, that might be called labial or lip fingers. These, it will be noticed, have immediate relation to the mouth. They are the organs for discriminating food—functionally they are manipulating lips. The stomach is not shown in the cut, being overlaid by the other organs. The intestine, at least a part of it, is exposed, and its extremity is really the anus or vent. So much, then, is apparent, that the oyster possesses an alimentary system of some complexity.
A series of plates or plaited frills, lies on the mantle, if indeed it is not a specialized portion of that organ. These plaits are the branchiæ or gills. In the respiratory system of an oyster these branchiæ or gills are precisely the same to it as are the gills to a fish, or our lungs to us. Through these gills the water is passed. After imparting to the blood the oxygen taken from the air which the water contained, that water, now laden with carbonic-acid gas, is expelled at the respiratory aperture, or ex-current orifice, the dark spot in the figure immediately under the end of the intestine, which we have already said is the anus or vent, whence this refuse water, like a cleansing stream, passes directly out of the shell. This contrivance is certainly very beautiful. It is in fact a miniature sewer carrying off promptly and quickly the excrements as fast as they are made.
The heart, constricted at the middle like the former silk purses of the ladies, is shown in place. The constriction separates the auricle and the ventricle. And so even an oyster has three sets of circulating organs, the heart with its double set of functions, and the arteries and veins. And this little organ beats with regular pulsations. That little auricle receives the blood from the gills, and that tiny ventricle is the vital force-pump that propels it into the arteries. "From the capillary extremities of the arteries it collects again into the veins, circulates a second time through the respiratory organ, and returns to the heart as arterial blood." The color of the oyster's blood is a pale bluish white—in fact it may be called opaline. Our oyster, then, is not a heartless thing. If you open it with care and skill, as would the naturalist, you may see and count the throbbings of its tiny heart.
In its proper place is seen the liver, which is always a large organ in the mollusca, or so-called shell-fish. It is true that this organ in the oyster secretes bile, and doubtless in large quantities. It is not probable, however, that this organ, though large, ever performs a metaphorical function, for it is very doubtful whether the oyster ever gets up the amount of emotion necessary "to stir one's bile." To the fast liver this oyster-liver is every thing. The secret is just here: this secretion of the liver is the real appetizer of the feast. This oyster-bile is both gustatory and digestive. It excites the glands of the palate and the secretions of the stomach.
The part indicated by the word muscle is the portion through which the knife, is passed when opening an oyster. In popular parlance it is sometimes called the "eye," and by some the "heart;" terms which, thus applied, are without meaning. It is the adductor muscle, and is the organ with which the oyster pulls-to its doors.
To sum up these considerations of the oyster's physiology, we see that, to the full extent of its necessities, it has distinctive sets of organs for the performance of the three classes of functions carried on in our own organization, namely, ingestion, respiration, and circulation.
The Oyster's Shell.—The toughest part of the oyster is the adductor muscle (Fig. 7). The office of this large, strong muscle is to pull-to and keep shut the great doors of the house. And a very curious bit of mechanism is subsidiary to this action. At the upper part of the cut is seen the hinge, a white spot with a dark curve below it. This dark curve is the hinge-ligament. It is a dark substance which fills up the pit or depression near the hinge. In the living animal it is wonderfully like gutta-percha—black, tough, and elastic. Let us attempt to explain its use to the oyster. Although this mollusk has a strong muscle with which to close its valves, it has not any with which to open them. Now, supposing we should take a lady's writing-desk, and, between the hinges at the back of the lids, should insert a piece of India-rubber, then should press down the lid, and turn the key; it is plain that the bolt of the lock now keeps the lid down, which could not be done simply by the weight of the lid, as before. Now, if we unlock the desk, up springs the lid, raised by the expansive force of the rubber at the hinges. This is precisely one of the functions of the hinge-ligament of the oyster. When the animal desires to shut up the valves, it contracts the great adductor muscle. When it needs to open them, it relaxes that muscle, and the valves open of themselves. Patrick's mishap was not merely amusing, regarded as a blunder, but even more so when viewed in this physiological light. He was told to go into the cellar and bring up some oysters in the shell; and his mistress gave him a strict charge not to bring any that were dead.
Patrick brought up a tray full, and every bivalve upon it was gaping wide! In reply to the astonished look of his mistress he said: "Sure, mam, they must be alive, or how could they keep their mouths open?" "But, Patrick," urged the lady, "could you not tell the difference by the smell?" "And sure, mam, I was remarking that same to meself. But mightn't the others have bad breaths too, if they'd only open their mouths a bit?" Had the matter been pressed to an explanation, perhaps the mistress would have been as severely taxed as the servant to render a reason.
The growth of an oyster-shell is always at the edge. It is effected by the rim of the mantle, as a series of delicate tips assorting the lime which is held in solution in the sea-water, and most daintily laying in its proper place the invisible cement. The precise method of the operation is not, I think, understood. It seems to me that the process is not a direct one, but rather the result of another process. All can recollect the once-popular mackintosh, a sort of water-proof cloak. It was little else than ordinary cloth, with an insoluble substance infused into the spaces between the fibres of the fabric. Is it not likely that the oyster has a process of its own not very dissimilar?—that it deposits a delicate net-work of animal substance as the staple, and that this is soon filled in with carbonate of lime, taken in mechanically from the salt-water? And this same organ has, along its edge, a series of pigment-cells, from which it exudes the paint that decorates the shell. In this respect the American oyster is a very plain affair. That of Europe has more color on the shell, I think, as it is more corrugated in form, and of less size. Our own oysters, we believe, both in quality and size, excel all others. (For a group of European oysters, of ages varying from that of three days to that of one year, see Fig. 2.)
If the shell of an adult oyster be examined, it will appear to be a series of shells, lying or lapping upon each other like tiles. There is, however, a difference. The lap of the upper one is not merely on the upper end of the lower one, but also on the middle, thus leaving a margin nearly all round. So the uppermost layer is always the smallest, and the lowermost one is always the largest of the series. The oystermen call these laps "shoots"—each one represents a season's growth. Thus each "shoot" shows the precise size of the oyster at a given year of its life, while the sum of the entire series gives the exact number of years the creature has lived. This shows how often the logic of Nature runs in parallel lines; for it brings up the old maxim again, "Every one to his own trade." The botanist counts the season-rings in the bole of a tree. The jockey tells the age of the horse by its teeth. The drover sets down the age of the cattle he buys by counting the rings on the horns; and in like manner the oysterman comes to a judgment by the number of "shoots" on the bivalve's shell. But all these specialists alike err when giving judgment upon an individual that has reached extreme old age.
The capability of the univalve mollusks to repair the shell when broken has been long known and understood by naturalists. In respect to the bivalves not so much is known. The oyster has some wonderful things in the way of repairing its house after being broken into. A case is known to us in which an oyster was so badly fractured at the nib that a piece of shell about an inch wide was broken off, and the poor animal protruded. An oysterman, for experiment's sake, restored it to the water, and, to be sure, put it close by a pole driven into the bed. This was in the spring. In September it was taken up and examined, when lo! the ingenious little builder had thoroughly repaired all damages!
The Nervous System of an Oyster.—Physically unstrung, the good old lady thus gave expression to her sufferings: "doctor, I'm getting so terribly nervous! I wish to goodness I'd no nerves at all, like an oyster!" An animal without nerves! One must go down very low in the scale of living things to find a creature enjoying such a dubious felicity. The amœba—a simple, gliding clot or molecule of living jelly—enjoys this singular distinction. It has no nerves. And of old time some of the philosophers even entertained no higher conception of the organization of the oyster. Nor was it any better with Seneca, the moralist, who so eloquently urged the practice of self-denial, and ascetic severity, and whose practical knowledge of the bivalve extended to the personal consumption of just one hundred at a time. These learned men knew nothing about amœbas, or they would surely have leaped to the conclusion that an oyster was an amoeboid animal shut up in a shell. Science, however, that sturdy non-respecter of persons, while it has pulled some things down, has lifted others up. Some of this exaltation has fallen to the oyster. Its nervous system is shown to be a very beautiful affair, and might be made the basis of some startling hypotheses in philosophy. It seems that, in common with the other learned men of his day, Plato regarded the oyster as the typical know-nothing of creation, and so, under the process known as transmigration, he judicially consigned the soul of the ignorant man at death to the occupancy of an oyster. Only to think of it! That last half-dozen fat mollusks one took so unsuspectingly down from the half-shell were possessed of an equal number of low, unlettered rapscallions in the spiritual state! You don't believe it? Of course. Who does? And it doth appear that Mr. Plato had but little to do when he was thus billeting bad company upon respectable people. Indeed, has he not much to answer for? A philosopher tempting to sin! Is not the man who stirs the pun as bad as the punster? Even at the risk of incurring punitive consequences, it must be said
That his metempsychosis
A contemptible joke is!—
a sentiment which, for want of prose, had to be thrown into rhyme. But it is urged in extenuation that this great man was only chaffing some old Greek who liked oysters, and that we ought to look rather to the wheat of his philosophy.
It is not intended here to go the length of declaring for the oyster that it has the feelings of a gentleman; although in Figuier the Scotch oyster-dredgers (Fig. 6) are represented as singing at their toilsome work:
"The herring it loves the merry moonlight,
The mackerel it loves the wind;
But the oyster it loves the dredger's song,
For it comes of a gentle kind!"
Let us look closely at Fig. 8, which represents the nervous system of an oyster. It is necessary, in the study of the nerves of the invertebrate animals, to use the word ganglion, which means a knot of nerves. Really, it signifies a little brain, so that an insect or a mollusk may have several brains in different parts of its body. It should be remembered, also, that in anatomy the forward or anterior end of an oyster is the part containing the mouth, and that is up against the hinge, while the posterior part happens in this case to be near the opening, or, as the oystermen call it, the nib of the shell. At b, then, we see the large brain of the oyster called the posterior ganglion. We see, too, that it is surrounded by nerves running to other parts of the structure. There are two curved branches, marked c c, which connect this brain with two comb-like objects. These are the nerves of the branchiæ or gills. This brain, then, has direct control of the mechanism and functions of respiration. But it is noticeable that it is
also connected with the entire system of the two nerve-lines, d d, which suggest the spinal cord of the vertebrates. And this double nerve-line crosses the two ganglia or little brains, a a, which are connected by the transverse nerve-branch e; thus the mouth, whose place is shown by the half-moon, is encircled by a nerve-ring, and this regulates the functions of ingestion. In those mollusks which travel, as do mussels and scallops, there is a ganglion or locomotive centre. Bearing this in mind, and the fact that the oyster does not have this ganglion, because it does not need it, not being a traveler at all, let us give the gist of Dr. Todd's remarks on the nervous system of the mollusca in general: "It affords a beautiful example of the complete analysis of the more complicated nervous system of the vertebrata. Have we not here distinctly marked out the cerebrum (the centre of volition and sensation), the medulla oblongata (the respiratory centre), and the cerebellum (the locomotive centre), as they occur in the higher vertebrata? And, in the aggregate of the chords by which the œsophageal ganglia communicate with the pedal and branchial ones, do we not see the analogue of at least a portion of the spinal cord, that portion which consists of afferent and efferent nerves to and from the brain?" It is plain, then, that, with a brain outfit of such a character and quantity, there must be something of a corresponding brain-force. In plain words, we mean that, possessing such a physiology, the oyster must sustain an analogous psychological relation. Organs imply functions. Pythagoras held that "animals have reason but no mind." Let us, then, see what sort of impressions an oyster can receive, and what kind of thinking it can do. If not too preposterous, we may even indicate its capacity to receive a modicum of education.
The adult oyster is eyeless, and of course blind. Yet it does without eyes that which we in its position could not do better with. It is affirmed that a bed of oysters has been seen to close by a precautionary impulse at the approach of a row-boat, even before the shadow of the approaching boat had reached them. Now, this is more than a blind man's distinguishing light from darkness. Is not that an exquisite sensitiveness which can thus note the faintest tint of shadow—the extremest margin of an oncoming obscuration?
Before the railroad days, our oyster-growers used early in the fall to canvass the villages on the Hudson River for orders, to be filled just before the river should be closed with ice. The meaning of this is that these men committed themselves to supply oysters in the shell, with the guarantee that the bivalves thus supplied should not die before their time came. The oysters were actually kept alive during the greater part of the long winter. The fat bivalves were handled with some care, and were spread on the cellar-floor, the round or lower side down, so as not to allow the liquor to escape. That such a life required a great change of capacity or habit in the bivalve is evident; and it needed a training, yes, an education, ere the oyster attained to such ability. And this was the way it was done: Beginning early in the fall, the cultivator of the oyster took up the fat bivalves from their bed where he had planted them, and laid them a little higher up on the shore, so that for a short time each day they were exposed out of the water. After a few days of this exposure by the retreating tide, they were moved a little higher still on the shore-line, which gave them a little longer exposure to the air at each low tide. And this process was continued, each remove resulting in a longer exposure. And with what results? Two very curious ones—inurement to exposure, and the inculcation of a provident habit of making preparation for the same. What! providence in an oyster? Yes, when he's educated. When accustomed to this treatment, ere the tide retires, the oyster takes a good full drink, and retains the same until the tide returns. Once, while waiting for the stage at a country hostelry, we overheard the following between two rustic practitioners at the bar: "Come, Swill, let's take a drink!" "Well, I don't know. Ain't dry myself. Hows'ever, guess I will take a drink, for fear I might get dry!" With better philosophy on their side, these educated oysters, twice in every twenty-four hours took their precautionary drink. The French method of oyster-training is much more laborious. The adult bivalves are carefully spread out in the water and periodical lessons are given to each one individually. Each oyster on this occasion receives a tap, not with a ferule, but with a small iron instrument. This causes the bivalve to close tightly. Finally the last day comes with its last premonitory tap. Its education thus finished, it takes passage with its fellow-graduates for Paris. As a result of its education, it knows how to keep its mouth shut when it enters society!
Said one of the English commissioners at the great World's Fair, in respect of the American inventions on exhibition, "They show so much knowingness!" So we think of this oyster-training; the American practice shows a common-sense tact, not found in the French method. And, though in a vastly more ancient sense, the secret of keeping oysters alive in the winter is an American art. Connected with the inland deposits of oyster-shells, made by the former Indian tribes in New Jersey, the writer has discovered what he believes to be oyster-preserves, the evidence of pits in which the Indians stored the living bivalves for winter consumption, when the bays and rivers of New Jersey were frozen over. While unearthing this Indian cache, the thought occurred, "How knowing these ancient people must have been!"
The next article will give, in detail, the friends and companions of the oyster; its enemies, with their modes of attack, and the geographical area of this bivalve.
- For some of the facts cited above, and in a few paragraphs immediately following, I am indebted to an able article in the Brooklyn Eagle, the date of which I cannot tell.—S. L.