Among the latest and most important observations on the hydrogen ion concentration of the human duodenum are those made by Hume, Dennis, Silverman and Irwin.1 Their subject was a colored man who had suffered a gunshot wound, the cause of which was unknown, and from which a duodenal fistula resulted. Their conclusions were that, "Electrometric determination of the hydrogen ion concentration of the human duodenum made by the insertion of an electrode through a fistulous opening gave a maximum pH 8.23 and a minimum pH 5.91; while the average calculated from 182 readings was pH 7.02. No definite difference in reaction was noted in observations made after the ingestion of meals consisting of fat, carbohydrate or protein."
McClure, Montague and Campbell,2 having obtained their material in a more customary manner, i. e., via a duodenal tube, secured results comparable to those of the aforementioned writers. Their material was obtained from