The blood of the Caucasian race is found to contain about ten parts of salt to the thousand, and this proportion of salt denotes firm tissue material. If the quantity of salt in the blood is diminished, the bi-concave red blood cells swell to a spherical form from access of water and lose their ability to unite for the production of connective tissue. Moreover, to the extent salt in the blood cells is decreased the connective tissue and muscle and tendon substance absorb water and the tissues become spongy, especially in the kidneys, so that the thinned blood albumen seeps through (urea albumen). Phosphate of potassium is the mineral basis of muscle tissue, phosphate of lime with a small amount of magnesium phosphate the basis of bones, and phosphate of ammonium the bases of nervous tissue. There is a sufficient quantity of phosphate in all healthy foods. When the milk fed to nurslings, however, is greatly thinned with water instead of firm muscle fibers and solid lymph glands we find loose and spongy tissues. This is a scrofulous condition. In the formation of healthy bones and teeth, calcium fluoride is essential. It is insoluble in plain water, but is made soluble by the aid of the glycocoll in blood gelatine and changed into ammonium fluoride. It appears in this form in the cartilaginous matter of the eye lenses, and lack of calcium fluoride in the food results in the clouding of these lenses. Silicic acid is not only indispensible to the growth of hair, but it forms a direct connection between blood and nerve tissues. It is found in birds eggs, both in the white and the yolk. It is a conservator of heat and electricity as it is a good insulator. It also possesses eminent antiseptic qualities. Its mere presence in the intestinal canal, even its simple passage through the canal; conserves the electrical activity of the intestinal nerves and thus influences the whole sympathetic nervous system. This brief review, cursory as it is, of the function of the minerals in the renewal of substances undergoing tissue change, makes it clear that our daily food must contain a sufficient quantity of them if healthy metabolism is to be maintained. Chemically considered the human body is one individual whole, its characteristic chemical basis being gelatine. Lieut. C.E. McDonald, U.S.A. Medical Corps, recognized this when he recently wrote: "The similarity of chemical compositions explains why, when any particular region falls a prey to chemical decomposition, others quickly become affected." Oxygen gas is the medium through which chemical combustion is carried on in the body for the purpose of preparing materials to enter into its composition. The mineral salts already named not only form the solid basis of the various tissue but also serve as conductors or insulators of electricity in the body. The absence of one of them for a protracted period is sufficient to explain widespread degeneration in the system.