costia Flats for the reduction of malarial fevers. 3. The enactment of a more stringent law regulating the production and sale of milk and dairy products, for the reduction of milk-borne diseases. 4. The abandonment of box privies, removal of slums, establishment of public baths for all seasons of the year, more liberal appropriations for the Health Department and a larger corps of sanitary inspectors so that the gospel of cleanliness and health may be enforced within and without the homes. 5. Greater co-operation on the part of the Police Courts with the efforts of the Health Department in the enforcement of sanitary laws and ordi

nances.

Some of these recommendations have been urged by the Commissioners for years; they are of vital importance to the health, not only of every permanent resident, but to the chief magistrate, his cabinet, the foreign ministers, thousands of public officials, the members of the Senate and House of Representatives, and all citizens having business with Congress, besides the numerous visitors who annually pay homage to the city of Washington.

ALIMENTATION AND FOODS.

The fact that proper nutrition of the body is important for the enjoyment of health has long since been recognized, and we all agree that the character of food not only influences the growth and development of the child, but also the health, power of endurance and resistance in the adult and often plays a most important if not decisive role in the treatment of disease.

The human organism is made up of about 60% of water, 19% of protein compounds, 15% of fats and 6% of mineral salts, all of which are sooner or later consumed, involving certain expenditures which must be covered if health and life are to be preserved.

The process by which the repair of waste is supplied is called alimentation or nutrition, and the entire process involved in the waste and repair of tissues is called metabolism. The simple chemical compounds which are appropriated by the system are called alimentary principles or nutrients, and the simple or artificial combinations of several nutrients are called nutriment or food.

The cause of the constant consumption of the proximate principles of the body must be looked for in the functional activity of the cells. We know that they take up, utilize, disintegrate and eliminate matter; this gives rise to the generation of heat and the evolution of force or mechanical power, both of which are the result of latent energy contained in the substances introduced into the system as food.

The heat and vital force of the heart and other muscles of the body have their source clearly in the process of oxidation of carbon and oxygen, which primarily takes place in the cells; and all nutrients containing carbon and hydrogen contribute to the generation of heat and the evolution of muscular force.

The chief objects of food are, according to Atwater, to form the material of the body and repair of its waste, and to yield heat to keep the body warm and muscular and other power for the work it has to do. The amount of energy contained in different food-stuffs has been measured in the laboratory by the amount of heat evolved during their combustion by means of an apparatus called the calorimeter. The unit commonly used is the calorie, by which we understand the amount of heat required to raise the temperature of a pound of water 1 degree F., or if transformed into mechanical power, such as the muscles use to do their work, a calorie represents force which would be sufficient to lift

one ton 1.54 feet. Atwater gives the following general estimate for the average amount of heat and energy in 1 pound of each of the classes of nutrients:

Since the supply of food stuff or income must be regulated by the consumption or outgo, it is essential that the consumption should be determined. Experiments of this kind are made in an apparatus called the "Respiration Calorimeter," and include not only a quantitative analysis of the food, drink and air consumed by the man and of all the excretory products, which make up the income and outgo of the system, but also a careful estimate of the energy represented by ingested material as well as the energy liberated from the body in the various excreta, in heat and mechanical energy.

The balance of income and expenditure is thus made, and the gain or loss of material of the body, with different kinds and amounts of food, and under different conditions of muscular exercise and rest, is determined. By means of these experiments, Prof. Atwater has been able to verify the law of the conservation of energy as applied to the animal organism, and has shown that every 'unit of energy which enters the body as potential energy of the food will leave the body in potential energy as excreta, in heat radiated from the body, or in mechanical work done by the muscular system. The material income of the body must balance the material outgo and the energy income of the body must balance the energy outgo.

According to the classical experiments of Pettenkoffer and Voit, nearly forty years ago, the waste products of a healthy adult weighing 154 pounds, during 24 hours, at rest amounted to 16.8 grams of nitrogen in the urine, 275 grams of carbon and 2,500 grams of water, while the waste products of the same individual, performing moderately hard muscular work, amounted to 18.8 grams of nitrogen, 328 of carbon and 2,190 grams of water, and from these experiments the authors named concluded that the following quantities of nutrients are required during 24 hours:

Professor Chittenden's experiments, conducted about three years ago,

indicate that the nitrogen equilibrium is preserved on a daily intake of 8.5 to 9.5 grams of nitrogen, or about 55 grams of nitrogenous food, so that the protein ration of Voit may be cut in two, provided the fats and carbohydrates are introduced in sufficient quantities to bring the full value up to 2,500 or 2,600 calories. Other authorities, however, believe that it would be unwise to reduce the protein ration below 100 grams or 3.5 ounces a day.

One of the difficulties in the way of setting up exact standards is as pointed out by Professor Atwater, that "different individuals of the same class differ widely in their demands for food and in the use they make of it. Two men of like age, size, build and occupation may live and work side by side. One will eat more and the other less, while both do the same amount of work, or both may eat the same food and do the same work, and one will be fat and the other lean, or both may have the same diet and yet one will be strong and vigorous and able to do a great deal of work, while the other will be weak and able to accomplish but little. Just why individuals differ in their ways of utilizing their food and how to measure the differences and make dietary rules to fit them exactly, are problems which the physiological chemist has not yet solved."

There are also persons who because of some peculiarity of the digestive system cannot use foods which for people in general are most wholesome and nutritious. Some persons cannot eat eggs, other suffer if they take milk, others have to avoid certain kinds of meat or fruit and all these indiosyncrasies indicate that the nutrition of man is not a mere matter of grams of protein, fats and carbohydrates. In fact we live not upon what we eat, but upon what we digest and assimilate.

The whole subject of dietary standards is still in its infancy and the best we can do is to make estimates which apply to averages rather than individual cases. In a general way we may conclude that the needs of the economy are influenced (1) by the height and weight of the individual amounting to a difference of 40-50 calories for each kilogram in body weight; (2) by the temperament-nervous and excitable persons require more food than those of a phlegmatic temperament; (3) by muscular activity, which involves not only an increased expenditure of carbon, but also increased consumption of protein. (4) Age in so far as during active growth there is also a more active metabolism and children consume more for each kilogram of their weight than adults; on the other hand, with advancing years tissue metamorphosis becomes less active. (5) Sex influences the amount of tissue consumption only in so far as there is a difference in weight and muscular activity, an exception should be noted in pregnant and nursing women, who doubtless should receive