STIMULATION of gastric secretion by insulin hypoglycemia has been used as a routine test for the integrity of vagus innervation of the gastric glands in both man and animals. In some manner the hypoglycemic reaction rather than the insulin itself stimulates the vagus, sympathetic, and other centers in the central nervous system. Preceding the stimulation of secretion there usually occurs a period of inhibition which is transient in the intact stomach1 and in separated vagus innervated gastric pouches2 but quite prolonged in vagus denervated Heidenhain pouches.2-6 The continuous or basal secretion of gastric juice is chiefly of nervous origin. Insulin hypoglycemia not only inhibits gastric secretion stimulated in this way but also that produced by endogenous and exogenous gastrin5 and histamine.4,6 The depression in gastric secretion usually accompanies the fall in blood sugar5,7 while the phase of stimulation usually begins somewhat later. The depression