The study covers variations of P, Ca, and Cl in human saliva, graphs and tables included. Samples of resting saliva and paraffin-activated saliva were used. The quantitative variations of constituents were greater in paraffin-activated than in resting saliva. There was no change in composition following a short fast. Oral ingestion of large amounts of soluble chlorides was followed by a temporary decrease of Cl in both saliva and blood plasma, while with abnormal ingestion of inorganic P the glands exercised marked excretory function. Variations were observed in the reactions of different individuals to the same stimuli; also, individual response to the same type of stimulus varied from time to time, so that normal variations in content of the respective constituents were sufficiently large to disguise any relationship that may exist.