An attempt has been made to determine the rate of parotid gland secretion on a group of manic-depressive patients while they were awake in the absence of marked extro-stimulation. Some hydrogen ion determinations were also made. The parotid gland secretion on one side for five minutes over a one hour period shows an average secretion withA. Normal subjects of .07 c. c., the range being from .02 to .15 c. c.B. Manic patients of .065 c. c., the range being from .03 to .09 c. c., this falling within the normal secretory range.C. Depressed patients of .005 c. c., the range being from .001 to .01 c. c., this rate being definitely below the normal secretory rate.Preliminary findings on the hydrogen ion concentration of the parotid gland secretions indicate a correlation between the secretory rate and the hydrogen ion concentration, namely, the higher the secretory rate the higher the pH. In other words the depressed patient has a more acid secretion than the average normal individual while the parotid gland secretion of the deteriorated præcox is less acid than that of the other groups.Abstract Teaser