This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
The well-known Oyster is a mollusc, possessing a mouth, a stomach, and intestines, but no head, nor eyes; it has a heart, a digestive gland, kidneys and a nervous system; its substance is specially rich in phosphates, such as serve for food to replenish defective structures, and to restore exhausted energy to invalids, or the sick. It has been extolled for these nutritive qualities since the old Roman days of Horace, and Martial, and of the Oyster-beds at Baiae, which was the Brighton of Rome. Our Early English Babee's Book has told of "Oysturs in ceny, Oysturs in grauey, your helthe to renew." And to-day Dr. Philpotts (1898) says: "The Oyster is good for the unborn child, good for the babe when two years old, good for adolescent youth, good for manhood in its maturity, and not only good for, but a main strengthener to, old age in its inevitable decay; it can make the sick well, render the healthy more vigorous, prolong the shortening days of senility, having imparted an additional charm to youth, and beauty." Again: "Living Oysters are endowed with their proper medicinal virtues: they nourish wonderfully, and solicit rest; for he who sups on Oysters is wont that night to sleep placidly; and to the valetudinary afflicted with a weak stomach, ten or twelve Oysters in the morning, or one hour before dinner, are more healing than any drug, or mixture that the apothecary can compound".
Oysters contain albuminous, gelatinous, and fatty matters, muscular filaments, and creatin. One of these molluscs is composed, speaking roughly, of water (eighty-five parts), organic matter (one and a half parts), with mineral matters, and silica (two and three-quarter parts). The Oyster is an admirable combination of food, and physic, because of its iodine, iron, sulphur, and marine lime salts; the liquor with which it is furnished inside the concave shell, when opened, being particularly rich in these curative, and restorative constituents. Five years are needed for the Oyster to attain its full growth. It consists of a hard, and a soft portion; the soft dark-green part is the liver, which is very digestible; the hard part is the muscle which binds the shells together, and is not so negotiable by weakly digestive powers. When Oysters are stewed, or scalloped, their albumin is coagulated by the heat, and becomes less easily soluble by the gastric juices of the stomach. The beard is the branchiae, or gills.
It has been said that the Oyster digests itself, because when the liver is crushed in eating, the hepatic cells are set free, and the glycogen is brought into contact with the hepatic ferment, thereby digesting the main part of the mollusc, with little effort of the stomach on the part of the partaker. If this view is correct an Oyster should be masticated in the mouth, and not swallowed whole. A marked difference is shown as to the action of cold water on the crushed, and uncrushed Oyster respectively; no less than half the solid matters are dissolved in the former case, but only one-fourth in the latter. Moreover, without doubt the Oyster's true flavour is appreciated most when the mollusc is masticated, a sweet taste being then given by the liver - glycogen. Its mineral matters comprise a minute portion of copper oxide, with chloride of sodium, phosphate of lime, and of magnesia, together with other soluble phosphates. It thus becomes shown that Oysters afford nutritive material of each class, - proteid, carbohydrate, fat, and mineral salts, - all of these food elements being present in a readily assimilable form.
But the proportion of solid nutriment in an Oyster is not large, three dozen of these molluscs of moderate size containing only from three to five ounces of solids; whilst their nitrogenous matter is not all proteid, but partly of a lower nutritive value. It would take fourteen ordinary Oysters to contain as much valid nourishment as one egg; therefore surprise need scarcely be felt at hearing of enormous meals being occasionally made of Oysters at one sitting. Seeing that the amount of glycogen, or liver sugar, contained in this mollusc is very small, it need not be pronounced unsuitable for a diabetic patient; its glycero-phosphatic compounds correspond to lecithin, as now used in medicine, from eggs, and other sources, for improving the nutrition of the nervous system. In the thickest part of the Oyster is its mass of olive-green liver. (Formerly the human liver was supposed to be the seat of love.) A property of stimulating the sexual impulses is ascribed to Oysters. "Oysters, and eggs," says Byron, "are amatory food".
The best solvent of the Oyster, next to cold water, is found by practical experiment to be gin, which also brings out the flavour considerably. Chablis is likewise said to be a good solvent, especially of the mineral matters contained in the Oyster; indeed, the whole of the phosphates are dissolved thereby. Champagne has probably the same effect; and because of its exhilarating gases it is an improvement on Chablis. Again, Stout is preferred by many persons as a beverage with Oysters, but "curiously enough" (says the Lancet, 1903) "it does not seem to have any solvent effect thereupon, probably because the Stout already contains a relatively large proportion of soluble matters." On concentrating the liquor which accompanies the Oyster within its shell, a brown liquid results which is indistinguishable, as regards taste and smell, from well-prepared beef-tea; it develops "osmazome " o a remarkable degree. The boiled Oyster yields scarcely any soluble matter to cold water, whilst it becomes tough, and indigestible by the process. Oysters contain an albuminous juice which increases in hardness with an increase of temperature, just as the albumin, or white of an egg does.
They should, therefore, when cooked be subjected to only a low degree of heat, and for a short time, it being borne in mind that 1608 Fahrenheit is the cooking temperature to coagulate albumen. In other words, to boil Oysters is to harden them, and to make them difficult of digestion.