GROUP VIII  . Phosphorus.—This includes phosphides, and, according to some authorities, hypophosphites . Phosphorus is present in all cells, in considerable quantity in the nervous tissue, and in the bones as phosphates . It is therefore, in some form or other, a necessary part of dietary . When taken by the mouth phosphorus is an irritant poison in large doses; in small doses the only effects noticeable consist in an increased formation of bony and connective tissue, although it is also supposed to exert a gently stimulating effect upon the nervous system .