The food should also contain the various elements which enter into nutrition in the proper quantity. The nitrogenous constituents in food, when subjected to the ordinary process of digestion, yield a certain quantity of heat and energy but their more important function is to nourish the nitrogenous elements of the body, of which the muscles, hair, skin, and finger-nails are types. The mineral constituents of food, especially phosphorus and lime, have a general utility in promoting the metabolic functions, especially in the movement of the fluids of the body through the cell walls, and at the same time are actual nourishing materials, entering particularly into the composition of the bones and teeth. The fats and oils which are present in the foods have the capacity of producing large quantities of heat and energy during their combustion in the body, and thus serve as a source of animal heat and muscular activity. The starches and sugars which are the most abundant elements of our food, although they have a heat-forming power of less than one-half that of fats, are largely utilized in the production of heat and energy and in the formation of animal fat. To secure a proper and complete nutrition of the body it is desirable that all these elements should be so adjusted as to provide for complete nourishment without having any one of them in great excess. It is evident that an excess of any one or more of these nutrient materials must necessarily impose on the organs of the body an additional work in securing their proper elimination. This tends to overburden the excretory organs and to cause a premature breakdown thereof. This giving away of the organs may not come for many years, not, perhaps, until advanced life, but when it comes it necessarily shortens the period of human existence. The term =“balanced ration”= means the adjustment of nutrients in the food in such a way as to secure complete and perfect nutrition without loading the body with an excess of any one element. This is also an important point on the score of economy. A large percentage of all the earnings of man is expended for food products, and hence these products should be used in a manner to secure the best results possible. If, by a practice of scientific nutrition, 10 percent of the value of foods could be saved it would create a fund which, could it be utilized, would minister in the highest degree to the comfort and welfare of the human family and form an abundant pension for old age. SOCIAL FUNCTIONS OF FOOD.