As the subject for my Edinburgh M.D. thesis I propose to take "The Etiology and Pathogenesis of Duodenal Ulcer", and especially deal with that most interesting and obscure form known as the "Solitary peptic ulcer of the Duodenum" . The subject of duodenal ulcer at the present moment is often referred to in current medical literature, and although in its beginning a purely medical subject, like gastric ulceration, yet it is to the surgeon that we owe the diagnosis in the great majority of cases, for as a rule, the condition is either diagnosed at a laparotomy for septic peritonitis, or else at an exploratory coeliotomy for some obscure gastrin disorder which proves to be secondary to an ulcer of the duodenum.