Food consists of substances taken into the stomach for the purpose of digestion, or of conversion into blood. Food is rendered necessary by the waste of the system. Food is the primary source of nervous and muscular power. Food which supplies calorific power is termed heat-forming, respiratory, carbonaceous, or fuel food, and consists of starchy, saccharine, or oleaginous bodies which contain a preponderance of carbon, or of carbon and hydrogen. Food which supplies dynamical, mechanical and mental power, is termed histogenetic (tissue forming), nitrogenous, azotized, proteinous or albuminous; and consists of substances which are comparatively rich in nitrogen, as milk, eggs, flesh, cheese, peas, beans and other bodies containing fibrin, albumen, caseine or gluten. A small portion of the respiratory food also probably contributes to the formation of the tissues; and likewise a portion of histogenetic or albuminous food to the development of the animal heat. The student and the hard-laboring professional man require even more tissue-forming food than the ordinary physical laborer. A due supply of animal food is necessary to the development of a high civilization; that is to the development of races who are capable of sustained muscular and mental labor.

Alcohol, either strong or dilute, cannot possess any histogenetic power from its deficiency of nitrogen; and, as far as the results of modern experiments can show, is neither oxidized nor burnt in the system, and therefore is probably neither a heat-former nor a flesh-former. It is consequently deficient in true food power, or, in other words, can neither nourish the body nor develop heat. A due mixture of heat-forming and flesh-forming food is most beneficial, economizing both food and digestive (vital or nervous) power. An excess of animal food is much more injurious than a corresponding excess of vegetable food. Cooking renders food more savory, wholesome and digestible, and destroys the parasitic animals which might otherwise excite serious if not fatal disease; it saves food, and enables the same amount of digestive (vital) power to do more effective work, and diminishes the quantity which would otherwise pass s away undigested. Any system of instruction in cooking which does not include some knowledge of the chemistry and physiology of food must be defective.