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 oys. terman 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: "O 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 amoeba-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 selfdenial, 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 amoebas, or they would surely have leaped to the conclusion that an oyster was an amœboid 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 in

VOL. VI.-2

vertebrate 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 branchise or gills. This brain, then, has direct control of the mechanism and functions of respiration. But it is noticeable that it is

d

FIG. 8.-THE NERVOUS SYSTEM OF AN OYSTER.

also connected with the entire system of the two nerve-lines, dd, 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 brainforce. 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 shadowthe 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