A Treatise on Physiology and Hygiene Part 7

2. WASTE AND REPAIR.--In this way the healthful body, though always wasting, is always building up, and does not greatly change in size, form, or weight. At two periods of life the processes of waste and repair are not exactly balanced. In early life the process of building up is more active, and in consequence the form is plump, and the stature increases. Repair now exceeds waste. On the other hand, when old age comes on, the wasting process is more active, the flesh and weight diminish, the skin falls in wrinkles, and the senses become dull. Only during the prime of life--from about twenty to sixty years of age--is the balance exact between loss and gain. {65}

[Sidenote: 3. System deprived of food? Warning? What is the pain? How proved?]

3. HUNGER AND THIRST.--When the system is deprived of its supply of solid food during a longer time than usual, nature gives warning by the sensation of hunger, to repair the losses that have taken place. This sensation or pain appears to be located in the stomach, but it is really a distress of the system at large. Let a sufficient quant.i.ty of nourishment be introduced into the system in any other way than by the mouth, and it will appease hunger just as certainly as when taken in the usual manner.

[Sidenote: 4. Feeling of thirst? Seat of the pain? How proved? Time a person can exist without food?]

4. The feeling of thirst, in like manner, is evidence that the system is suffering from the want of water. The apparent seat of the distress of thirst is in the throat; but the injection of water into the blood-vessels is found to quench thirst, and by the immersion of the body in water, the skin will absorb sufficient to satisfy the demands of the system. The length of time that man can exist without food or drink is estimated to be about seven days. If water alone be supplied, life will last much longer; there being cases recorded where men have lived twenty days and over, without taking any solid food.

[Sidenote: 5. Amount of food required? The young and others? Those living in hot and cold climates? Habits?]

5. QUANt.i.tY OF FOOD.--The quant.i.ty of food required varies greatly, according to the individual and his mode of life. The young, and others who lead active lives, or who live in the open air, require more food than the old, the inactive, or the sedentary. Those who live in cold regions require more than the inhabitants of hot climates. Habit, also, has much to do with the quant.i.ty of food required. Some habitually eat and drink more than they actually need, while a few eat less than they should.

[Sidenote: 6. Quant.i.ty of food daily? How divided? Compare with the weight of the body?]

6. The average daily quant.i.ty of food and drink for a healthy man of active habits is estimated at six pounds. This amount may be divided in about the following {66} proportions: the mineral kingdom furnishes three and one-half pounds, including water and salt; the vegetable kingdom, one and one-half pounds, including bread, vegetables, and fruits; the animal kingdom, one pound, comprising meat, eggs, b.u.t.ter, and the like. This quant.i.ty is about one twenty-fourth the weight of the body, as it is generally computed; the average weight of an adult man being placed at 140 pounds. A man, therefore, consumes an amount of solid and liquid nutriment every twenty-four days equal in weight to that of his body, a corresponding amount being _excreted_, or removed from the system in the same time.

[Sidenote: 7. How often then might the body be renewed? Why is it not?

Opinion? How correct? What further is stated?]

7. RENOVATION OF THE BODY.--By this process, so far as weight is concerned, the body might be renewed every twenty-four days; but these pounds of food are not all real nutriment. A considerable portion of that which we eat is innutritious, and though useful in various ways, is not destined to repair the losses of the system. An opinion has prevailed that the body is renewed throughout once in seven years; how correct this may be it is not easy to decide, but probably the renovation of the body takes place in a much shorter period. Some parts are very frequently renewed, the nutritive fluids changing more or less completely, several times during the day. The muscles, and other parts in frequent exercise, change often during a year; the bones not so often, and the enamel of the teeth probably never changes after being once fully formed.

[Sidenote: 8. Habits of nations? Give the different cases.]

8. MIXED DIET.--The habits of different nations in respect to diet exhibit the widest and strangest diversity. The civilized, cook their food, while savages often eat it in a raw state. Some prefer it when fresh, others allow it to remain until it has become tainted with decay. Those dwelling in the far north subsist almost wholly on {67} animal food, while those living in hot climates have bountiful supplies of delicious fruits with which to satisfy all their bodily wants. One race subsists upon the banana, another upon the blubber of seals. In temperate climates, a diet composed partly of vegetable and partly of animal food is preferred.

[Sidenote: 9. The point to consider? Vegetable diet? Louis Cornaro? John the Baptist?]

9. The important point to consider is, however, not one of origin, but whether the chemical principles (mentioned in the last chapter) enter into the composition of the diet. A purely vegetable diet may be selected which would contain all the principles necessary to sustain life. It is recorded of Louis Cornaro, a Venetian n.o.ble, that he supported himself comfortably for fifty-eight years on a daily allowance of twelve ounces of vegetable food, and about a pint of light wine. On the other hand, the food of John the Baptist, consisting of "locusts and wild honey," is an example of the sustaining power of a diet chiefly animal in its origin.

[Sidenote: 10. What has been found in our climate? Exclusive vegetable diet?]

10. In our climate, those who lead active lives crave an allowance of animal food; and it has been found by experience that with it they can accomplish more work and are less subject to fatigue, than without it.

Among nations where an exclusively vegetable diet is employed, indigestion is a disorder especially prevalent.

[Sidenote: 11. Necessity for change in diet? Continuous use of the same diet? Exception? Why? Too rich diet? Horses?]

11. The necessity for occasionally changing or varying the diet, is seen in the fact that no single article comprises all the necessary principles of food, and that the continuous use of any one diet, whether salt or fresh, is followed by defective nutrition and disease. There is one exception to this rule: in infancy, milk alone is best calculated to support life; for then the digestive powers are incompletely developed, and the food must be presented in the simplest form possible. It should also be remembered {68} that too rich diet is injurious, just as truly as one that is inadequate.

When the food of horses is too nutritious, instinct leads them to gnaw the wood-work of their mangers.

[Sidenote: 12. Milk as a model food? Cow's milk? The const.i.tuents when separated?]

12. DIFFERENT ARTICLES OF DIET--MILK.--Milk is the earliest nutriment of the human race, and in the selection and arrangement of its const.i.tuents, may be regarded as a model food, no other single article being capable of sustaining life so long. Cow's milk holds casein, one of the alb.u.minoids, about five parts in one hundred; a fatty principle, when separated, known as b.u.t.ter, about four parts; sugar of milk four parts; water and salts eighty-seven parts. The casein and fatty substance are far more digestible in milk, than after they have been separated from it in the form of cheese and b.u.t.ter.

[Sidenote: 13. Milk as a beverage? Milk sold in cities? How to detect the cheat?]

13. Since milk, in itself, is so rich an article of food, the use of it as a beverage is unwise, unless the quant.i.ty of the other articles consumed be reduced at the same time. The milk sold in cities is apt to be diluted with water. The way to detect the cheat is by testing the specific gravity of the article. Good milk is about 1030; skimmed milk 1035; but milk diluted one-fifth is 1024. An instrument called the lactometer is also used, by which the amount of cream present is ascertained.

[Sidenote: 14. Composition of eggs? Yolk? How should eggs be eaten? Why?

How boiled? Why?]

14. EGGS.--The egg is about two-thirds water, the balance is pure alb.u.men and fat in nearly equal proportions. The fat is in the yolk, and gives it its yellow color. Eggs contain none of the sugar-principles, and should be eaten with bread or vegetables that contain them. Soft-boiled eggs are more wholesome than those which are hard-boiled or fried, as the latter require longer time to digest.

[Sidenote: 15. Meats, whence derived? Why important? Flesh of young animals?]

15. MEATS.--The meats, so called, are derived from the muscular parts of various animals. They are most {69} important articles of food for adults, inasmuch as they are richly stored with alb.u.minoid substances, and contain more or less fat. Such food is very nourishing and easily digested if eaten when fresh,--veal and pork being exceptions. The flesh of young animals is more tender and, in general, more digestible than that of older ones. All meat is more tough immediately after the killing of the animal, but improves by being kept a certain length of time.

[Sidenote: 16. Preference of persons? Venison? Mutton? Cheese? Uncooked flesh?]

16. Some persons prefer flesh that has begun to show signs of decomposition, or is unmistakably putrid. By some, venison is not considered to have its proper flavor until it is tainted. In England, people prefer mutton that is in a similar condition, just as on the continent of Europe many delight in cheese that is in a state of decomposition. In certain less civilized countries flesh is not only eaten uncooked, but in a mouldy, rotten condition. The use of such food is not always immediately injurious, but it predisposes to certain diseases, as indigestion and fevers.

[Sidenote: 17. Cold as a preserver? Meat in Russia? Beef and pork, how preserved? Salted meat as food? Scurvy?]

17. Cold is one means of preserving meat from decay. In the markets of northern Russia, the frozen carcases of animals stand exposed for sale in the winter air for a considerable time, and are sawn in pieces, like sticks of wood, as the purchases are made; such meat, when thawed, being entirely fit for food. Beef and pork are preserved by salting down in brine, and in this condition may be carried on long voyages or kept for future use.

Salted meat is not as nutritious as fresh, since the brine absorbs its rich juices and hardens its fibres. Long continued use of salt meats, without fresh vegetables, gives rise to the disease called scurvy, formerly very prevalent on shipboard and in prisons; but now scarcely known.

[Sidenote: 18. The antiquity of the custom of cooking food? Object of cooking? The oyster? Raw meat as an occasional food?]

18. COOKING.--The preparation of food by the agency {70} of fire is of almost universal practice, even among the rudest nations. The object of cooking is to render food more easy of digestion by softening it, to develop its flavor, and to raise its temperature more nearly to that of the body. A few articles of flesh-food are eaten uncooked in civilized lands, the oyster being an instance. Raw meat is occasionally eaten by invalids with weak digestive powers, and by men training for athletic contests.

[Sidenote: 19. Effect of boiling meat? How may the cooking be done? The proper method? Effect? Making of soup?]

19. In boiling meat, the water in which it is placed tends to dissolve its nutrient juices. In fact, the cooking may be so conducted as to rob the meat of its nourishment, its tenderness, and even of its flavor. The proper method, in order to preserve or promote these qualities, is to place the meat in boiling water, which, after a few minutes, should be reduced in temperature. In this way the intense heat, at first, coagulates the exterior layers of alb.u.men, and imprisons the delicate juices; after that, moderate heat best softens it throughout. When soup is to be made, an opposite course should be pursued; for then the object is to extract the juices and reject the fibre. Meat, for such purpose, should be cut in small pieces and put into cold water, which should then be gradually raised to boiling heat.

[Sidenote: 20. Roasting? How should it be done? Give the philosophy of the process. Frying?]

20. Roasting is probably the best method of cooking meat, especially "joints" or large pieces, as by this process the meat is cooked in its own juices. Roasting should begin with intense heat, and be continued at a moderate temperature, in order to prevent the drying out of the nutritious juices, as by this process an outer coating or crust of coagulated alb.u.men is formed. During this process the meat loses one-fourth of its weight, but the loss is almost wholly water, evaporated by the heat. Too {71} intense or prolonged heat will dry the meat, or burn it. Frying is the worst possible method, as the heated fat, by penetrating the meat, or other article placed in it, dries and hardens it, and thus renders it indigestible.

[Sidenote: 21. What is "Trichina?" How guarded against?]

21. TRICHINA.--It should be remembered that ham, sausages, and other forms of pork, should never be eaten in a raw or imperfectly cooked condition.

The muscle of the pig is often infested by a minute animal parasite, or worm, called _trichina spiralis_. This worm may be introduced alive into the human body in pork food, where it multiplies with great rapidity, and gives rise to a painful and serious disease. This disease has been prevalent in Germany, and cases of it occur from time to time in this country.

[Sidenote: 22. What part of fish is eaten? What does it resemble? Fish as food for digestion? Fish as a diet?]

22. FISH.--The part of fish that is eaten is the muscle, just as in the case of the meats and poultry. It closely resembles flesh in its composition, but is more watery. Some varieties are very easy of digestion, such as salmon, trout, and cod; others are quite indigestible, especially lobsters, clams, and sh.e.l.l-fish generally. A diet in which fish enters as the chief article, is ill adapted to strengthen mind or body, while its continued use is said to be the fertile source of nearly every form of disease of the skin. Some persons are so const.i.tuted that they can eat no kind of fish without experiencing unpleasant results.

[Sidenote: 23. List of vegetable articles? Usefulness of the different vegetables? Strychnia? What further is said in relation to the nourishing and other qualities of vegetables?]

23. VEGETABLE FOOD.--The list of vegetable articles of diet is a very long one, including the grains from which our bread-stuffs are made, the vegetables from the garden, and the fruits. All the products of the vegetable kingdom are not alike useful. Some are positively hurtful; indeed, the most virulent poisons, as strychnia and prussic acid, are obtained from certain vegetables. Again, of such {72} articles as have been found good for food, some are more nourishing than others: some require very little preparation for use, while others are hard and indigestible, and can only be used after undergoing many preparatory processes. Great care must therefore be exercised, and many experiments made, before we can arrive at a complete knowledge in reference to these articles of diet. Tea, coffee, and other substances from which drinks are made, are of vegetable origin.

[Sidenote: 24. Wheat? "Staff of life?" White flour? Hard-grain wheats?

Bolting? Graham bread?]

24. BREAD.--Wheat is the princ.i.p.al and most valuable kind of grain for the service of man. Bread made from wheat-flour has been in use for many hundreds of years, and on this account, as well as because of its highly nourishing properties, has been aptly called "the staff of life." We never become tired of good bread as an article of daily food.

The white kinds of flour contain more starch and less gluten than the darker, and are therefore less nutritious. The hard-grain wheat yields the best flour. In grinding wheat, the chaff or bran is separated by a process called "bolting." Unbolted flour is used for making brown or Graham bread.