at a glance. The amount of refuse contained in foods (such as the bones of meat or fish, the exoskeleton of crustaceans and mollusks, the woody coverings of plant cells) is also shown in this table.

A Mixed Diet Best. - Knowing the proportion of the different food substances required by man, it will be an easy matter to determine from this table the best foods for use in a mixed diet. Meats contain too much nitrogen in proportion to the other substances. In milk, the proportion of proteids, carbohydrates, and hydrocarbons is nearly that of protoplasm; a considerable amount of mineral matter is also present. For these reasons, milk is extensively used as a food for children, as it combines food material for the forming of protoplasm with mineral matter for the building of bone. Some vegetables — for example, peas and beans contain the elements needed for protoplasm formation in nearly correct proportions, but in a less digestible form than is found in some other foods. Vegetarians, then, are correct when they state that a diet of vegetables may contain everything necessary to sustain life and build tissues. A mixed diet, however, has been found to be preferable. A purely vegetable diet contains much material, such as the cellulose which forms the walls of the plant cells, which is indigestible. Because of the small amount of proteid usually present in vegetables, a larger bulk of food material is taken; thus the organs of excretion are given increased work. The Japanese army ration consists almost entirely of rice. A recent report by their surgeon general intimates that the diminutive stature of the Japanese may, in some part at least, be due to this diet. Starch or sugar alone would be an unwholesome diet, because of the lack of nitrogen and overabundance of carbon.

FOOD ECONOMY. The American people are far less economical in their purchase of food than most other people. Nearly one half of the total income of the average working man is spent on food. Not only does he spend a large amount on food but he wastes money in purchasing the wrong kinds of food. The table on the following page (modified from Atwater),1 shows how economy may be exercised in the purchase of foods.

ADULTERATIONS IN FOODS.—Many foods which are artificially manufactured have been adulterated to such an extent as to be almost unfit food or even harmful. One of the commonest adulterations is the substitution of grape sugar (glucose) for cane sugar. Most cheap candy is so made. Flour and other cereal foods are frequently adulterated with some cheap

1 W. O. Atwater, Principles of Nutrition and Nutritive Value of Food. U.S. Dept. of Agriculture, 1902.

substitute; the list of adulterated articles is almost inexhaustible. Purefood laws have been passed by Congress, which strike at this evil.

IMPURE WATER.

One danger far greater than the above-mentioned comes from drinking impure water. This subject has already been discussed under Bacteria, where it was seen that the spread of typhoid fever in particular is due to a contaminated water supply. As citizens we must aid all legislation that will safeguard the water used by our towns and cities. Boiling water for ten minutes or longer will render it safe from all organic impurities.

FOOD WASTE IN THE KITCHEN.. Much loss occurs in the improper cooking of foods. Meats especially, when overdone, lose much of their flavor and are far less easily digested than when they are cooked rare. The chief reasons for cooking meats are that the muscle fibers may be loosened and softened, and that the bacteria or other parasites in the meat may be killed by the heat. The common method of frying makes foods less digestible. Stewing is an economical as well as healthful method. A good way to prepare meat, either for stew or soup, is to place the meat, in small pieces, in cold water, and allow it to simmer for several hours. Rapid boiling toughens the muscle fibers by the too rapid coagulation of the albuminous matter in them, just as the white of egg becomes solid when heated. Broiling and roasting are excellent methods of cooking meat. In order to prevent the loss of the nutrients in roasting, it is well to baste the meat frequently; thus a crust is formed on the outer surface of the meat, which prevents the escape of the juices from the inside.

Vegetables are cooked in order that the cells containing starch grains may be burst open, thus allowing the starch to be more easily attacked by the digestive fluids. Inasmuch as water may dissolve out nutrients from vegetable tissues, it is best to boil them rapidly in a small amount of water. This gives less time for the solvent action to take place. Vegetables should be cooked with the outer skin left on when it is possible.

Stimulants. We have learned that food is anything that supplies building material or releases energy in the body; but some materials used by man, presumably as food, do not come under this head. Such are tea and coffee. When taken in moderate quantities, they produce a temporary increase in the vital activity of the person taking them. This is said to be a stimulation; and material taken into the digestive tract, producing this, is called a stimulant. In moderation, tea and coffee appear to be harmless. Some people, however, cannot use either without ill effects. It is the habit formed of relying upon the stimulus given by tea or coffee, that makes them a danger to man. In large amounts, they are undoubtedly injurious because of a substance, called caffeine, contained in them.

Alcohol. The question of the use of alcohol has been of late years a matter of absorbing interest and importance among physiologists. Dr. Atwater performed a series of very careful experiments by means of the respiration calorimeter, to ascertain if alcohol is of use to the body as food. In these experiments, the subjects were given, instead of their daily allotment of carbohydrates and fats, enough alcohol to supply the same amount of energy that these foods would have given. The amount was calculated to be about two and one half ounces per day, about as much as would be contained in a bottle of light wine. This alcohol was administered in small doses six times during the day. Atwater's results may be summed up briefly as follows:

Professor

1. The alcohol administered was almost all oxidized in the

body.

2. The potential energy in the alcohol was transformed into heat or muscular work.

3. The body did about as well with the rations including alcohol as it did without it.

The committee of fifty eminent men appointed to report on the physiological aspects of the drink problem, reported that a large number of scientific men state that they are in the habit of taking alcoholic liquor in small quantities, and many report that they do not feel harm thereby. A number of scientists seem to agree that within limits, alcohol may be a kind of food, although a very poor food. The following statements support this view:

"The conclusion to which all the evidence points is that alcohol is a food, and in certain circumstances, such as febrile conditions, it may be a very useful food; but in health, when other kinds of food are abundant, it is unnecessary, and as it interferes with oxidation, it is an inconvenient kind of food." -T. LAUDER-BRUNTON, A Text-book of Pharmacology, Therapeutics and Materia Medica (London, 1887), page 768.

"If oxidized even to a small extent, and the evidence, as indicated, points to the oxidation of by far the larger proportion of it, ninety five per cent alcohol must be regarded in the scientific sense as a food. . .

1 Alcohol is made up of carbon, oxygen, and hydrogen. It is very easily oxidized, but it cannot, as is shown by the chemical formula, be of use to the body in tissue building because of its lack of nitrogen.

2 Alcoholic beverages contain the following proportions of alcohol: beer, from 2 to 5 per cent; wine, from 10 to 20 per cent; liquors, from 30 to 70 per cent. Patent medicines frequently contain as high as 60 per cent alcohol.