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“ fattening" them. If the weather is warm, they will take a “drink” inmediately, if not disturbed; but if the weather is cold, they will wait sometimes ten or twelve hours before opening their valves. Good fat oysters generally yield five quarts of solid meat to the bushel; but, after floating two tides or more, they will measure six quarts to the bushel. After they have been properly floated they are taken from the shell—and as soon as the liquor is all strained off, they are washed in cold fresh water—and are then packed for market. In warm weather they are put into the water with ice, and are also packed with ice for shipping. Water increases their bulk by absorption and by mixing with the liquor on the surface of the oysters. The salter the oyster the more water it absorbs. In twelve hours one gallon of oysters, with their juices strained out, will take in a pint of water; but when very salt and dry, they have been known to absorb a pint in three hours.
Water always thickens the natural juices that adhere to the surface of the oyster, and makes them slimy. If too much water is added, the oyster loses its plumpness and firmness and becomes watery and flabby.
Oysters that have been floated bear transportation in the shell much better than when shipped directly from their beds. Oysters, too, that are taken from their shells and packed in all their native juices spoil much sooner than when their juices are strained out and the meats are washed in fresh cold water.
Long clams are not floated, but round clams are. But both, when shucked, are washed in fresh water. This cleanses them of mud, sand, and excess of salt, increases their bulk, and improves their flavor. After washing they will keep much longer without risk of spoiling. If the salt is left in them, as they come from their native beds, their liquor will ferinent, and they will quickly spoil.
The above facts are gathered from the most intelligent men in the shell-fish business in Connecticut,men who have had many years' experience in gathering oysters and clams, and preparing them for home and foreign consumption. They are all agreed that by judicious floating in the shell, and by washing and soaking when out of the shell, the oyster and the clam increase in bulk and improve in quality and flavor. We will not presume to say that this increased bulk is anything more than a mechanical distention of the organs and the cellular tissues of the oyster by water; or that its improved flavor is not due simply to a loss of bitter sea-salt dissolved out by the water. Many intelligent cultivators are confident that the increase in bulk is a growth of fat; while just as many, of equal intelligence, declare that it is mere “bloat” or distention, akin to that of a dry sponge when plunged into the water. The exact nature of the change the chemist alone can determine.
The following experiments were made with oysters courteously supplied by Mr. Lane, a communication from whom was just quoted. The oysters had been brought from the James and Potomac Rivers, and “planted” in the beds in New Haven Harbor (Long Island Sound) in April, and were taken for analysis in the following November.
Two experiments were made. The plan of each experiment consisted in analyzing two lots of oysters, of which both bad been taken from the same bed at the same time, but one had been “floated ” while the other bad not. For each of the two experiments, Mr. Lane selected, from a boat-load of oysters as they were taken from the salt water, a number, about three dozen, which fairly represented the
whole boat-load. The remainder were taken to the brackish water of a stream emptying into the bay and kept upon the floats for fortyeight hours, this being the usual practice in the floating of oysters in this region. At the end of that time, the oysters were taken from the floats, and a number fairly representing the whole were selected as before. Two lots, one floated and the other not floated, were thus taken from each of two different beds. The four lots were brought to our laboratory for analysis.
The specimens as received at the laboratory were weighed. Thereupon, the shell-contents were taken out, and the shells and shell-contents both weighed. The solid and liquid portions of the shell-contents -i. e., the flesh or “solids ” and liquor or “ liquids"-were weighed separately, and then analyzed. We thus had, for each lot, the weights of flesh and liquids which, together made the weight of the total shellcontents, and the weight of the shells, which with that of the shellcontents made the weight of the whole specimens. We also had, from the analyses, the percentages of water, nutritive ingredients, salts, etc., in the flesh and in the liquids. From these data the calculations were made of the changes which took place in floating. For the details, which are somewhat extended, I may refer to the publication mentioned above. It will suffice here to give only the main results. It is assumed that the changes in the composition of the body of the animal, due to respiration, nutrition, excretion, etc., during the floating would be too small to be taken into account.
The body of the animal may be regarded as made up of water and so-called water-free substance. The water-free substance contains the nutritive ingredients or “nutrients." These may be divided into four classes : 1. Protein compounds, the so-called “flesh-formers," which contain nitrogen* ; 2. Fatty substances, classed as fats ; 3. Carbohydrates ; 4. Mineral salts. These constituents of the flesh of oysters have been but little studied. It is customary to assume them to be similar to the corresponding compounds of other food-materials, but very probably the difference, if known, might prove to be important. The mineral matters especially, which are very large in amount, appear to include considerable of the salts of sea-water. Of the nature of the ingredients of the liquids but little is known. They consist mainly of water and salts and the amounts of their ingredients which are commonly reckoned as protein, fats, and carbohydrates, are very small, so that whatever error there may be in classing them with the ordinary nutrients of food, it will not very seriously affect the estimates of nutritive values.
During the sojourn in brackish water, both the flesh (body) and the liquid portion of the shell-contents of the oysters suffered more or less alterations in composition. In order to show clearly what the principal changes, as shown by the chemical analyses, were, it may perhaps be permissible to cite a few of the statistics. I give more details than would perhaps be appropriate in these pages, were it not for the novelty of the results, and the importance of their bearing upon the physiology of absorption of nutritive material in our bodies as well as upon the nutritive value of the oysters.
* The protein is estimated in the usual way by multiplying the nitrogen by 6.25.
The changes in the constituents of the body (“flesh") were mainly such as would be caused by osmose, though there were indications of secretion of nitrogenous matters and, especially, of fats, which are not so easily explained by osmose. This I will speak of later.
The amounts of gain and loss of constituents which the bodies of the oysters experienced may be estimated either by comparing the percentages found by analysis before and after dialysis, or by comparing the absolute weight of a given quantity of flesh and the weights of each of its ingredients before, with the weights of the same flesh and of its ingredients after, dialysis. For the estimate by the first method we have simply to compare the results of the analyses of the floated and the not-floated specimens. Taking the averages of the two experiments, it appears thatThe percentages of
After dialysis Water rose from ....
82:4 Water-free substancc fell from
176 Total flesh....
100.0 Protein fell from.....
8.9 Fat fell from ..
1.9 Carbohydrates, etc., fell from
02 Mineral salts fell from
10:5 2.5 6.9 2:2
Total water-free substance in flesh .....
There was, accordingly, a gain in the percentage of water and a loss in that of each of the ingredients of the water-free substance. This accords exactly with the supposition that during the floating the flesh gained water and lost salts and other ingredients.
It will be more to the point to note the absolute increase and decrease in amounts of flesh and its constituents—in other words, the absolute gain or loss of each in the floating. Estimates by this method have been made and explained in the detailed accounts referred to. They make it appear that 100 grammes of the flesh as it came from the salt water was increased by floating, in one specimen, to 120-9, and in the other to 113.4 grammes. This is equivalent to saying that the two specimens of flesh gained in the floating, respectively, 20-9 and 134 per cent, or, on the average, 17.3 per cent of their original weight. By the same estimates the water-free substance in the 100 grammes of flesh before the floating weighed, on the average, 22.1 grammes, while that of the same flesh after floating weighed only 20.6 grammes, making a loss of 1.5 gramme or 6:6 per cent of the 22:1 grammes which the water-free substance weighed before dialysis. The main results of the two experiments thus computed, may be stated as follows: In the “floating ” of 100 grammes of flesh (body) of the oystersThe weight of
77.9 grammes to 96-6 grammes. Water-free substance fell from .
In brief, according to these computations, the flesh lost between one sixth and one seventh of its mineral salts, one eighth of its carbohydrates, and one twelfth of its fats, but gained enough water to make up this loss and to increase its whole weight by an amount equal to from one seventh to one fifth of the original weight. Assuming the loss of nutritive value to be measured by the carbohydrates and fats which escaped, it would amount to about one tenth of the whole. That is to say, the total nutritive materials were one tenth less after floating than before.
In the liquid portion of the shell-contents, the percentage of water rose and that of the water-free substance fell in a very marked degree. But while the whole percentage of water-free substance was diminished, that of both protein and of carbohydrates rose slightly (the amount of fats was too small to be taken into account), so that the falling off was all in the mineral salts. The experiments do not show the exact increase or decrease in the total amounts of the liquids and their constituents, so that it is impossible to say with entire certainty whether there was or was not an actual gain of protein or fats or carbohydrates. It would seem extremely probable, however, that the liquids received and retained small quantities of these materials from the flesh (bodies) of the animals.
The apparent increase of protein and other materials belonging to the body in the liquids, though slight, is very interesting. I must refer to the detailed account of the experiments for the discussion of it and of the changes in composition of the liquids. The point is that if the changes in composition of the oysters in floating were due to osmose or dialysis alone, we should expect simply a gain of water and loss of salts (and perhaps of soluble carbohydrates). But the flesh seems to have lost a little carbohydrates and fats, and probably protein also, along with the salts, while it was absorbing water, the liquids at the same time gaining more or less of protein and carbohydrates. A A way in which this may have come about is suggested by my colleague, Professor Conn, who calls attention to the fact that some mol.
lasks, when irritated, produce an extremely abundant secretion of mucus or “slime"—so much, indeed, as to sometimes render a small quantity of water in which the animals may be confined, quite sensibly gelatinous. He suggests that the change to fresh water may induce such a secretion of mucus, and perhaps of carbohydrates and fats as well, as would account for the increase of these substances in the liquids. The observation of oyster-dealers that “water always thickens the natural juices that adhere to the surface of the oyster and makes it slimy,” accords with Professor Conn's statement.
If such secretion did take place, the flesh must probably have lost a little protein during the floating. The estimates of absolute gain and loss of weight of flesh and ingredients are based upon the assumption that the quantity of protein was unaltered in floating. If protein was given off, therefore, the estimates are wrong. But the quantity of protein secreted and the consequent error must be, at most, very slight. If there is an error, its effect would be to make the quantities of putrients after floating appear larger than they really were. In other words, if the error were corrected, it would make the loss of nutritive material in floating greater than it appears to be in the figures above given.
The experiments might have been so conducted as to decide this question of the exact gain and loss of weight of each material in the oysters. It would have been necessary to simply take a larger number in each lot before and after floating, and be certain that the number, weight, and bulk were the same in the floated and not-floated lots of each experiment. For instance, we might, in each experiment, carefully select two lots of, say, a busbel each, as taken from the beds; have the number of oysters the same in each bushel, as an additional assurance that the two lots were alike; float one bushel, and weigh and analyze both. A few experiments of this sort made under different conditions of time, temperature, kind, and age of oysters, etc., would give very reliable and valuable data. Unfortunately, the means at my disposal did not permit so thorough experiments. I am persuaded, however, that the results of such series of trials, if they could be made-and I wish they might be-would be very similar to those of the trials here reported.
It is very interesting to note that these processes of both osmose and secretion which we have been considering in the body of the oyster are apparently very similar to processes which go on in our own bodies-namely, those by which our food, after it is digested, finds its way through the walls of the stomach and other parts of the alimentary canal into the blood, to be used for nourishment. Physiologists tell us that the passage of the digested materials through the walls of the canal is in part merely a physical action, due to osmose, but that it is in part dependent upon a special activity of the cells of the villi. In like manner, the changes in the composition of the ops