"Mr. Byram Littlenow, of Huddersfield, England, exhibited oysters produced by artificial contact of the sperm and ova in artificial seawater by a process of his own invention. He claims that while an American experimenter has succeeded in hatching the oyster, no one but himself has succeeded, as yet, in growing it beyond one of the earliest stages of development. He showed living specimens, which he had kept in continuous growth from three to five months, which is as long as he has been experimenting in that direction, and expressed full confidence in the practicability of hatching and rearing oysters abundantly and profitably."-Report of Edinburgh Fisheries Exhibition.

There is so much left unsaid in the above that entire confidence is hardly possible. We, then, must confine ourselves to more open achievements. Last summer, Dr. John A. Ryder advanced a little beyond Dr. Brooks in artificial propagation. With Col. McDonald, in an apparatus devised by the Colonel, the fixation of the fry to the sides of the glass hatching-vessel was obtained in twenty-four hours from the impregnation of the eggs. Each of the young fry was attached by one side, having already got its larval shell. The shells were round and symmetrical, becoming unsymmetrical as the spat grew, although, for the time observed, there was no apparent growth in these three-days-old spat. They seemed cemented to their holdingplace by a deposit of concholine, that horn-like substance observed on the edge of oyster shells. At first, there was no nib or beak extending beyond the hinge. It seemed as if these points were cut squarely off. When the shells begin to grow, these points appear and are extended, which seems about the earliest external change in form. Conchologists call these points of the shells, in all bivalves, the umbones, hence Dr. Ryder names this early period in the life of the fry the "umbo stage." In his "Summary," published in Forest and Stream, he further says: "Sections of the soft parts of spat, from a sixteenth to a quarter of an inch in diameter, show that the intestine and stomach are arranged pretty much as in the adult, the main difference being that the intestinal folds are not so pronounced and the liver follicles comprise the bulk of the body mass."

Though there may seem a little want of agreement, it would hardly serve the present purpose well to omit the following: From his paper in The Microscope, October, 1882, it seems that Dr. H. J. Rice had already carried the study of the attached fry to a point beyond all others. The article being long and rather technical, I must quote this

interesting young biologist with some freedom of language: The gill-flaps of the larval oyster, which is several days old, now begin to appear. (To this we will add, as our belief, that the cilia are meanwhile being absorbed as nutriment.) The rudimentary gills, which are fluted or grooved, soon take on innumerable and almost infinitely small cilia, which, lashing along the grooves, cause the minute food in the water to pass up them. Here is a singular provision to manipulate the food. Dr. Rice says that, in 1878, he discovered an organ or adaptation, which he calls the proboscis, hence he names this period of the little thing's life the "proboscis stage." Speaking of this rudimentary organ, the Doctor says: "The protrusive œsophagus grows out into a slender and quite flexible proboscis, which is only slightly, if at all, extensible, and is provided at its extremity with a spreading and very mobile lip or rim, which surrounds the mouth orifice."

"In pushing this waving bit of tissue to one side with the end of a pencil, it spread out at the end and closed about the point of the pencil, clasping it quite firmly, and upon closer inspection I found that the bit of tissue represented the end of the alimentary canal, and that the portion clasping the point of the pencil was in reality a lip-like flap surrounding the mouth orifice of the canal. The proboscis was endowed with a certain responsive action, since, whenever the point of the pencil was brought in contact with it, the proboscis would move about and the lip be directed towards the point of contact, when the pencil would be clasped as in the first instance. If left to itself the proboscis would move slowly about in the water, waving from side to side, as when first noticed, spreading and closing its lip extremity as if feeling for something in the surrounding fluid."

The oyster should indeed be a dainty, for in the matter of its living few things are more squeamish. There are so many nice points essential to its well-being-proper depth of water, suitable bed to lie on, and suitable depth of ooze or mud, that it may not get smothered; the temperature and saltness of the water, the kind and quantity of its food. It is even affected by drought and excess of rain, and the force of the winds. With all things favorable, its babyhood is very brief, its growth becomes rapid, and its condition good. Dr. Rice found oysters in the proboscis stage in sizes from one-eighth of an inch to one and threeeighths inches, and has found them having passed the embryonic stage when but three-eighths of an inch diameter. At this stage the oystermen call them "spat," or "blisters," and the spawn so attached is said

to have "set." In less than a year it becomes about as large as a dollar, and is then known as "seed," since it is of proper size for planting. Lieut. Winslow, speaking of the oysters in Chesapeake Bay, in 1879, says:

"In the first three months the oyster increased in size from a hardly visible speck to an average length of one and a quarter inches, and a few were over two inches long. The lower and attached side grows most rapidly, and during this period the growth is mainly in length. After the first year the increase in size is not so rapid; and oysters of two or three years of age are about two inches broad and three inches long, though these dimensions will vary in different localities. In three years at the most the American oyster is considered mature, and will present all the characteristics of those found in the markets," size only excepted.

Having traced the oyster from the egg to the swimming stage, thence to its earliest fixed state, the umbo stage, thence through a part of its organic development, or proboscis stage, and lastly to its full spat or seed condition, we are now to consider it in its adult stage and form.

3. SHELL-STRUCTURE AND CARDINAL PARTS OF THE MOLLUSK.

An oyster shell is in two parts, as the word bivalve implies. The upper part is the smaller of the two, and is the part from which the oyster is eaten, when taken on the half-shell. The under, or lower side is larger, much more rounded, and is deeply dished, and heavier. It is on this side the animal lies when normally positioned in the water. The thin part, where the knife enters, when opening the oyster, the oystermen call the nib; and the extreme opposite end at the hinge, they call the bill or beak. Between the upper and the lower beak is the ligament, a black, tough substance looking not unlike gutta percha. Though very brittle after death, it is quite elastic in life. It holds the valves together, and is really in its way a leather hinge. As mentioned already, it is elastic, and when the valves are drawn together, that is, when the oyster shuts his shells, this ligament is squeezed and compressed. The valves are closed by the pull of the great adductor muscles, the part vulgarly called the eye by some, the heart by others. When this strong muscle is slacked the compression of the ligament is relaxed, and it immediately expands, and so lifts up the lighter valve, that is, opens the shell; so that though an oyster can shut his house by pulling to the door, the door is opened automatically by a purely

mechanical device. The animal does not really open it of itself, but lets it be opened. On the inside of each valve is a deep or sunken scar of varying color, usually of a dark chestuut. These two scars mark the place of attachment of the two opposite ends of the great muscle. Now as the pull of this muscle is very strong, should it always remain attached near the hinge, the labor of the pull would increase with the increase of length of the shell by annual growth, until the leverage would become so great that the animal would not be strong enough to overcome it; that is, the time would come when the tenant would be unable to shut his own doors. To obviate so serious a danger the animal moves its attachment towards the nib, keeping up with the yearly increasing length of its shell, thus effectually preventing any increase of leverage. These changes of the place of attachment of the muscle are controlled by the amount of shell extension or growth, and the last attachment, while always advancing towards the nib, never reaches it, but is kept sufficiently far from it to sustain a hold on the thick part of the shell, for if it came too near the nib, that would be too thin for a well-sunken hold of the muscle into the shell. The effect of this annual removal of the scar-pit is to make a long depression or groove, which would so alter the form of that part of the shell in which the animal lies as to become inconvenient for the position of its organs. To prevent this the creature, as the muscle moves forward, fills up the canal behind with nacre or mother of pearl.

"It is

As already shown, the oyster only when in its larval state has the capacity of locomotion, and even then only by its cilia, not by any pedal organ proper, such, for instance, as that by which a clam ploughs and progresses through the mud. Still, to our surprise, the ingenious malacologist, Mr. W. H. Dall, attached to the United States Fish Commission, has discovered the pedal muscle in the oyster. attached to the valves near the hinge in Ostrea Virginiana by a small purplish scar." I have a noble oyster taken this winter from a native bed in Raritan Bay, near Sandy Hook, which shows both these pedal scars very finely. However, this muscle is at best only rudimentary, and is unusable for locomotion. Is it a relic of a more highly endowed ancestral oyster with pedestrian habits? Robert L. Pell, in his prize essay, "Edible Fishes of New York," written in 1858, probably draws from the depths of his consciousness in saying: The oyster has "an organ called a foot, composed of layers of fibres, which by contraction and expansion bestow on it the

power of locomotion in a small degree." It is enough to say that if let alone the oyster makes a life-long attachment.

The growth of an oyster shell is entirely from within. The lime carbonate is spread in a thin lamina over the inside of each valve, thus thickening them, and this thin layer is pushed outwards, the deposit at the edges, however, being at first a grayish, semi-horny or animal matter called conchioline, upon and into which this carbonate of lime is laid. By this process the shells are widened and lengthened. The effect of this mode of increasing the size is to add, shingle-wise, a series of laps, or what are called "shoots." The youngest shoot, that is, the last one made, seems to be pushed out from the inside of the shell, which is the fact, and the old "shoot" is the little shingle highest up on the outside and close to the hinge. At the hinge, in the trough of the lower beak, is a series of parallel lines. These are the terminal edges of the planes, or layers of increase, recording, as do the "shoots," in my opinion, the annual shell growth. I once heard a man of more than the ordinary intelligence claim that these flaps or shoots denoted "moon growths." How suggestive this of the notion advocated by some, that the supposed annual rings in the boll of a tree are only season growths. As to the shell of our bivalve, the series of shoots, and that of the hinge-lines, also that of the musclescars have a correlation, and if rightly made out should tell the age of the oyster in years, since, as I view them, they do record the annual accretion or growth of the shell. Twenty years has been set down as the limit of an oyster's life. This is not correct. In February, 1882, I published in Popular Science Monthly an article-" The Longevity of the Oyster." Two oysters taken up at Keyport, N. J., were subinitted to me to tell their age. One was seven inches long, and three and a-half inches wide; the other was seven and a-half by four inches. Both specimens were quite uniform in their markings. It was evident that their growth had been slow and regular, and that the edges of the shoots had been worn smooth. All these points tallied with the facts. They were taken from a poor bottom-sandy and hard-and the smoothness was due to the rocking by the water on the sandy bed. Plainly, they were transplanted "Virginias." I depended for my diagnosis mainly on the hinge-lines, for the increase had been so gradual as to make the task difficult. The hinge groove was in places coated with a limey deposit of bryozoa, thus in part obliterating the lines. As was to be expected, the beak, with its groove of the lower