Protein: as white (albumen) of eggs, curd (casein) of milk, lean meat, gluten of wheat and grains and other vegetable proteid (formerly called legumen) - Forms tissue.

Fats: as fat of meat, butter, olive oil and other vegetable oils - Are stored in the body as fat.

Carbohydrates: as sugar, starch, etc. - Are transformed into fat.

Mineral matters: as phosphates of lime, soda, etc. - Share in forming bone, assist in digestion.

All act as fuel, yielding energy in the form of heat and muscular power.

The most common proteids are white of eggs, lean meat, the casein of milk, the gluten of wheat, and the proteid of vegetables (found in peas, beans, and lentils). The protein of vegetables is less easily and completely digested than that of meat, and though most useful it is not quite so valuable as the more easily assimilated animal food. Chloride of sodium (common salt) and lime, both important elements in the formation of teeth and bone, and in maintenance of the integrity of the system, are largely found in fresh fruits, vegetables and grains. Often the supply of fresh fruit and vegetables is limited during the winter season, and in the spring the system calls for elements that have been wanting, True common salt has been supplied in the food, and lime may have been given, but these crude substances are not identical with the lime and salt contained in fruit, vegetables and grains. Here these substances have been orgainzed and fitted for appropriation by animal life, while in an unorganized state they tend to disturb digestion. The evidence is strong that common salt, in excess, may cause kidney disorders, leading even to Bright's disease. In making out dietaries the first thing to determine is the part which a food must perform for the individuals in question. Are they building or only repairing tissue? Are they active or sluggish ? Is the temperature in which they live warm or cold? The foregoing summary of this chapter is largely adapted from a schedule by Professor Atwater.