This section is from the book "Human Physiology For The Use Of Elementary Schools", by Charles Alfred Lee. Also available from Amazon: Human Physiology, for the Use of Elementary Schools.
7. Savours, like odours, are innumerable, and as they dif fer so much from each other, it is impossible to classify them in any satisfactory manner. We can readily understand what is meant by the terms sweet, bitter, sour, saline, acrid, etc, yet each of them differs in intensity, as well as other shades of character. For example, rectified sugar, brown sugar, maple sugar, beet sugar, molasses, honey, etc, are all sweet, but the taste of each is different. Linneus and Booer haave both made a classification of savours, but they have never been generally adopted by physiologists. Adelon divides them into two kinds, the agreeable and disagreeable. But even this division is not founded in nature ; for we find the old adage true, that " one man's meat is another man's poison." Every person has some peculiarities of taste, dislikes to particular articles of food, or shades of difference in the appreciation of tastes, which may be constitutional, or caused by association. Besides, the taste sometimes becomes unaccountably morbid or depraved. We often see children devouring chalk, brick dust, ashes, dirt, and slate pencils, when if, at other times, they were required to swallow such articles, as medicine, they would doubtless deem it a peculiar hardship.
8. Savours differ as to the permanence or transientness of impression which they leave upon the organs of taste. Aromatic and bitter substances particularly leave their taste in the mouth for a long time after they have been swallowed ; the physician, therefore, when he wishes to administer some nauseous drug, forestalls the sense of taste, by directing one of these substances to be held previously in the mouth. There is a common experiment on this subject, which has led to many bets, viz., giving to a person blindfold, brandy, rum, gin, or any other spirituous liquor in rapid succession, and see whether he can tell one from another. In a short time, the nerve becomes so impregnated with the different substances, that all distinction becomes confounded. Tasters of wine, tea, etc, understand this principle ; for we see them take up a small portion and move it over the whole surface of the mouth, so as to extend its action, and then they wait for some time after the impression is made before they taste of other samples. When a person takes a medi cinal draught, he gulps it down as quick as possible, in order that it may come in contact with as small a portion as possible of the organ of taste.
9. The taste is greatly under the influence of habit. Many articles which at first excite disgust, being taken through fashion or necessity, at length become highly grateful. We need only name tobacco, and perhaps ardent spirits. The taste for these substances is altogether artificial, no one being fond of them, -when taken for the first time. Such perversion of taste often becomes national. Thus garlic forms a constant ingredient in the dishes of some European coun tries. The most celebrated sauce of antiquity, was the Roman garum, prepared from the half putrid intestines of fish. Another of their favourite condiments was assafoetida ; and this is still in high repute among many of the orientals. Rotten eggs are highly esteemed by the Siamese, and fish in an advanced state of decomposition is highly relished in the northern and western islands of Scotland. Dried, putrid mutton is habitually eaten in Iceland, and epicures in every country esteem game and venison a greater luxury, if in a putrescent state. To be a fashionable epicure of the present day, requires that the taste should be educated or trained, like a sportsman's setter. It is then prepared to scent out,' with infallible certainty, what fashion has taught it to relish as choice luxuries ; but which simple, unadulterated taste, rejects as fit only for the kennel or the carrion crow.
10. The gratification which we derive from eating depends chiefly on the state of the stomach. If that is not in a condition to digest food properly, no matter how much we may generally relish any particular article ; it will, at such times, invariably excite disrelish or even disgust. So also when we sit down with a keen appetite to a meal, as our hunger is appeased, the relish proportionally diminishes, till at length we reach the point of satiety, and if we persist, nausea and disgust are certain to succeed. Here then, is another wise provision, informing us with infallible certainty when we have taken sufficient food to supply the wants of the system. The ancient Romans availed themselves of a knowledge of this law, and hence were in the habit of leaving the table once or twice during a meal, and after having, by means of an emetic, unloaded the stomach, of returning again to the charge.
11. As a general rule, articles that are agreeable to the taste, are safe and nutritious, though this is not invariably the case. For example, prussic acid has a very agreeable savour, as well as odour, and is accordingly used to impart flavour to dishes and liqueurs, such as noyeau, yet prussic acid is one of the most powerful poisons in nature. Many substances which at first are highly agreeable, in a short time lose their relish ; we see that grocers understand this principle, for instead of forbidding a new apprentice from eating sugar, raisins, honey, and molasses, he tells him to eat all he wants, knowing, that in a short time, his appetite will be cloyed, and all temptation removed.
12. Among animals, we find a great difference in the perfection of this sense. Some enjoy it, doubtless, in as great, if not a greater degree than man, as they are able by it to distinguish plants that are nutritive and good for food, from those which are poisonous; and accordingly it is a rare thing for animals to die from eating such vegetables. Many insects feed on the leaves of poisonous plants, and some animals eat the leaves of the poison ivy without injury. There is an insect which feeds on the leaves of the tobacco, and the southern planter guards against its ravages by a process called worming. The taste also in animals sometimes becomes morbid, as we see it happen among our own race. Mr. Bennet, in his " Wanderings in New South Wales" states, that serious losses happened to the farmers in that country from the sheep acquiring the habit of licking and devouring earth impregnated with saline matter. In a short time, he says, their natural innocent dispositions become changed, and they become carniverous and savage, and devour the lambs. Thus out of a flock of twelve hundred lambs, eight hundred were devoured by the sheep themselves.