For many years there has been a popular belief that calcium and phosphorus metabolism was somewhat directly associated with the function of the nervous system. Textbooks1on clinical diagnosis have reported observations of decreased phosphoric acid and increased calcium content of the urine in cases of "neurasthenia," and a diminution in the relative amount of phosphoric acid excreted during "periods of excitement" in "mental disease." The general statement is made that patients having heavy deposits of phosphates in the urine are "usually subjects of nervous disorders, and frequently of sexual neurasthenia." The relation of calcium and phosphorus metabolism to "nervous disorders" is uncertain, but it is now known2that the amount of calcium or phosphorus excreted in the urine is dependent on very complex physicochemical processes which have no specific relation to the function of the nervous system. It has long been assumed that the body tissues, in