In a paper on acquired diverticulitis of the large intestine, in 1907, Wilson, Giffin and I1were able to demonstrate the pathology and to outline the clinical history of the condition to which Graser2called attention in 1898. Our five cases in which the diverticulous sigmoid was excised proved to be the first recorded in which an actual demonstration of the pathology of diverticulitis was established during life. Articles dealing with postmortem demonstrations of diverticula of the colon had been rather frequent,3and suggested an explanation of clinical experiences such as those recorded in the contributions of Telling,4Brewer,5Beer,6Plummer7and others. Since the recognition of the condition, we have resected portions of the large intestine for diverticulosis in forty-two cases. In thirty-six the sigmoid was involved, in one the transverse colon, in one the ascending colon, in one the hepatic flexure