For many years, diverse compounds containing phosphorus have been made topics of special emphasis in relation to medical problems. The highly toxic element phosphorus has been reputed to be a "nerve stimulant" and "reconstructive tonic." Some of its salts can produce no better recommendation than the vague claim of being "tonics." Sodium phosphate has an independent part as a saline cathartic, which is not associated with the previously mentioned medicinal virtues. Organic phosphorus compounds, notably the complex fat derivatives like lecithin, have been charged with exerting specially desirable effects in the direction of nutrition. One reads that they favor constructive metabolism in the body.
It is conspicuously true that complex phosphorus compounds are found widely distributed in the organism, where they unquestionably exert important functions and have specialized uses. It is not without significance, we presume, that phosphatids like lecithin and kephalin are found in practically every cell, or that