« PreviousContinue »
to meet an emergency, when a ring of the proper kind could not be procured in time. In parts of Ireland, however, there is a current belief that a ring of gold must be used, and jewelers in the country towns not infrequently hire gold rings to peasants, to be returned after the ceremony.
Blessing the ring gives it no small share of sanctity, and old missals contain explicit directions as to the manner in which this ceremony must be carried out. In the church-service as performed in the vil. lages of England, the ring is frequently placed in the missal, the practice being, no doubt, a relic of the blessing once thought indispensable. The German peasant-women continue to wear the wedding-ring of the first husband, even after a second marriage, and a recent book of German travels mentions a peasant wearing, at one time, the weddingrings of four “late lamenteds.” An instance is known of a woman of German birth, who, after the death of her husband in a Western State, had the misfortune to lose her ring. She at once bought another, had it blessed, and wore it instead of the former, deeming it unlucky to be without a wedding-ring. Among the same class of people, stealing a wedding-ring is thought to bring evil on the thief, while breaking the emblem of marriage is a sure sign of speedy death to one or both of the contracting parties.
THE CIIEMISTRY OF “OYSTER-FATTENING."
By W. 0. ATWATER,
PROFESSOR OF CHEMISTRY IN WESLEYAN UNIVERSITY.
which are so highly prized in the great American bivalve, and which are so attractive in specimens on the half-shell or in the stew as to lead the average man to pay a considerable extra price for extra size, are not entirely natural ; and even those who do know that the majority of the oysters in the market are artificially swollen by introducing water into the tissues are not all aware that the process by which this is done is closely analogous to that by which the food in our own bodies is conveyed through the walls of the stomach and other parts of the digestive apparatus and poured into the blood and lymph to do its work of nourishment.
Physiologists are, I believe, agreed that the passage of the digested food through the walls of the alimentary canal in man and other animals is, in large part, due to osmose or dialysis, and that the operation of this physical law is a very common one in the animal body. But the quantitative study of the chemical changes involved is generally rendered difficult or impossible by the very fact of their taking place in living animals where the application of chemical analysis is impossible. An opportunity is, however, offered by the oyster, which, since it lives in water and has a body so constituted as to readily permit the iniow and outflow of water and solutions of salts, may be easily used for experiments. The results of the experiments bave a practical as well as scientific interest, since they confirm the common explanation of the increase in bulk of oysters by “floating,” and show that it is essentially a process of watering in which the bulk is increased without any corresponding increase, but rather, if anything, a loss of nutritive material.*
It is a common practice of oyster-dealers, instead of selling the oysters in the condition in which they are taken from the beds in salt water, to first place them for a time-forty-eight hours, more or lessin fresh or brackish water, in order, as the oyster-men say, to “fatten" them, the operation being called “floating" or "laying out.” By this process the body of the oyster acquires such a plumpness and rotundity, and its bulk and weight are so increased, as to materially increase its selling value.
The belief is common among oyster-men that this “fattening” is due to an actual gain of flesh and fat, and that the nutritive value of the oyster is increased by the process. A moment's consideration of the chemistry and physiology of the subject will make it clear, not only that such an increase of tissue-substance in so short a time and with such scanty food-supply is out of the question, but that the increase of volume and weight of the bodies of the oysters is just what would be expected from the osmose which would naturally take place between the contents of the bodies of the oysters as taken from salt water and the fresh or brackish water in which they are floated.
If we fill a bladder with salt water, and then put it into fresh water, the salt water will gradually work its way out through the pores of the bladder, and, at the same time, the fresher water will enter the bladder; and, further, the fresh water will go in much more rapidly than the salt water goes out. The result will be that the amount of water in the bladder will be increased. The bladder will swell by taking up more water than it loses, while at the same time it loses a portion of the salt.
It does this in obedience to a physical law, to which the terms osmose and dialysis are applied. In accordance with this law, if a membranous sac holding salts in solution is immersed in a more dilute solution, or in pure water, the more concentrated solution will pass out, and at the same time the water, or more dilute solution, will pass in, and more rapidly. The escape of the concentrated and entrance of the dilute solution will be, in general, the more rapid the greater the difference in concentration and the higher the temperature of the two solutions. After the osmose bas proceeded for a time, the two solutions will become equally diluted. When this equilibrium between
* The following statements are adapted from a paper presented to the last meeting of the American Fisheries Association.
the two is reached, the osmose will stop. If the sac which has become distended is elastic, it will, after osmose has ceased, tend to come back to its normal size, the extra quantity of solution which it has received being driven out again.
We should expect these principles to apply to the oyster. Roughly speaking, the body of the animal may be regarded as a collection of membranous sacs. It seems entirely reasonable to suppose that the intercellular spaces, and probably the cells of the body, would be impregnated with the salts of the sea-water in which the animal lives; and this supposition is confirmed by the large quantity of mineral salts which the body is found by analysis to contain, and which amount, in some cases, to over fourteen per cent of the water-free substance of the body.
It seems equally reasonable to believe that osmose would take place through both the outer coating of the body and the cell-walls of the animal's body. As long as the oyster stays in the salt water, the solution of salts within its body would naturally be in equilibrium with the water outside. When the animal is brought into fresh or brackish water, i. e., into a more dilute solution, we should expect the salts in the more concentrated solution within its body to pass out, and a larger amount of fresh water to enter, and produce just such a distention as actually takes place in the floating. If this assumption is correct, we should expect that the osmose would be the more rapid the less the amount of salts in the surrounding water, that it would proceed more rapidly in warm and more slowly in cold water; that it would take place whether the body of the animal is left in the shell or is previously removed from it; that the quantity of salts would be greatly reduced in floating ; and that, if it were left in the water after the maximum distention had been reached, the imbibed water would pass out again, and the oyster would be reduced to its original size. Just such is actually the case. Oyster-men find that the oysters “fatten” much more quickly in fresh than in brackish water; warmth is so favorable to the process that it is said to be sometimes found profitable to warm artificially the water in which the oysters are floated. Although oysters are generally floated in the shell, the same effect is very commonly obtained by adding fresh water to the oysters after they have been taken out of the shell ; indeed, I am told that this is a by no means unusual practice of retail dealers. Oysters lose much of their salty flavor in floating, and it is a common experience of oyster-men that, if the “fattened ” oysters are left too long on the
floats, they become "lean " again.
This exact agreement of theory and fact might seem to warrant the conclusion that the actual changes in the so-called fattening of oysters in floating are essentially gain of water and loss of salts. The absolute proof, however, is to be sought in chemical analysis. In the course of an investigation conducted under the auspices of the United
States Fish Commission, and which included examinations of a number of specimens of oysters and other shell-fish, I have improved the opportunity to test this matter by some analyses of oysters before and after floating. The results of the investigation are to be given in detail in one of the publications of the Commission,* in which the principles involved and some side-issues of the experiments will be discussed. I give here the main results, prefacing by brief accounts of the process of “floating” oysters as actually practiced by oyster-men.
The following very apposite statements are by Professor Persifor Frazer, Jr., who attributes the changes mentioned to dialytic action :
The oysters brought to our large markets on the Atlantic seaboard are generally first subjected to a process of " laying out,” wbich consists in placing them for a short time in fresher water than that from wbich they have been taken.
Persons who are fond of this animal as an article of food, know how much the "fresh ” exceed the “salts” in size and consistency. The “Morris Coves" of this city (Philadelphia), while very insipid, are the plumpest bivalves brought to market. On the other hand, the “ Absecoms” and “Brigantines," while of a better flavor (to those who prefer salt oysters), are invariably lean compared to their transplanted rivals, as also are the “ Cape Mays," though, for some reason, not to the same extent.
The most experienced oyster-dealers inform me that the time for allowing the salt oysters taken from the sea-coast to lie out varies, but is seldom over two or three days. At the end of this time the maximum plumpness is attained, and beyond this the oyster becomes lean again, besides having lost in flavor.
The subjoined statements by Lieutenant J. A. Ryder are interesting in this connection. They are taken from a letter to Professor Baird, United States Commissioner of Fish and Fisheries, on “Floats for the So-called Fattening of Oysters" : 1
The simplest and most practical structures of the kind which I have seen are the storage and fattening floats used by Mr. Conger, of Franklin City, Maryland, and now in use by all the shippers and planters in the vicinity of Chincoteague Bay. I have been informed that similar structures, or rather structures serving similar purposes, are in use on the oyster-beds along the shore of Staten Island, New York.
It is probably a fact that in all these contrivances they take advantage of the effect produced by fresher water upon oysters which have been taken from slightly salter water. The planters of Chincoteague call this “plamping the oysters for market.” It does not mean that the oysters are augmented in volume by the addition of substantial matter, such as occurs during the actual appropriation of food, but only that the vascular spaces and vessels in the animals are filled with a larger relative amount of water due to endosmose. It is a dealer's trick to give his produce a better appearance in the market, and as such I do not think deserves encouragement, but rather exposure.
* A detailed account is also to appear soon in the “ Zeitschrift für Biologie.”
+ “Note on Dialysis in Oyster-Culture,” in “Proceedings of Philadelphia Academy of Sciences,” 1875, p. 472.
“Bulletin of the United States Fish Commission,” 1884, p. 302.
Mr. Conger has actually resorted to warming fresh water to 60° Fahr. in winter, by steam-pipes running underneath the wooden inclosure surrounding the “fattening" or "plumping ” float. One good “drink," as he expressed himself to me, renders the animals fit for sale and of better appearance.
Conger's floats are simply a pair of windlasses supported by two pairs of piles driven into the bottom. Chains or ropes which wind upon the windlasses pass down to a pair of cross-pieces, upon which the float rests, which has a perforated or strong slat bottom, and a rim eighteen inches to two feet high. These floats I should think are about eight feet wide and sixteen feet long, perhaps twenty. These structures are usually built alongside the wharves of the packing and shipping houses, and are really a great convenience in conducting the work.
Elsewhere Lieutenant Ryder speaks of the floats thus :
The diaphragm itself was constructed of boards perforated with auger-holes, and lined on the inside with gunny-cloth or sacking; and the space between the perforated boards was filled with sharp, clean sand. The space between the boards was about two inches; through this the tide ebbed and flowed, giving a rise and fall of from four to six inches during the interval between successive tides.
Mr. F. T. Lane, of New Haven, Connecticut, writes as follows about the method of floating practiced by himself, and, as I understand, by other New Haven oyster-growers :
We do not always leave them two days in the floats—as a rule, only one day. We put them into brackish water and take them out at low water or in the last of the falling tide, as then the water is the freshest and the oysters are at their best. As it is not convenient for us to put them into the floats and take them out the same day, we do not want the water too fresh. On one occasion, wishing to know what the result would be of putting the oysters into water that was quite fresh, I had one of my floats taken up the river, half a mile farther than where we commonly use them, and one hundred bushels of oysters put into it at high water and taken out at low water. They were in the water from six to seven hours and came out very nice, fully as good as those floated twenty-four hours in the brackish water. It was a warm day, and the water was warm. Under these conditions they will drink very quickly. I have seen them open their shells in ten minutes after they were put into the water.
For the following valuable information I am indebted to Mr. R. G. Pike, chairman of the Board of Shell-fish Commissioners of Connecticut :
Connecticut oysters, when brought from their beds in the salt waters of Long Island Sound, are seldom sent to market before they bave been subjected to more or less manipulation. As soon as possible after being gathered, they are deposited in shallow-tide rivers where the water is more or less brackish, and are left there from one to four days; the time varying according to the temperature of the season, the saltness of the oysters, and the freshening quality of the water. Generally two tides are sufficient for the two “good drinks " which the oyster-men say they should always have.
This “floating," as it is called, results in cleaning out and freshening the oysters, and increasing their bulk; or, as many oyster-men confidently assert,