The differential diagnosis of duodenal ulceration from other intra-abdominal lesions in patients with “an ulcer history” is a subject of perennial interest and debate between clinician and roentgenologist. That the problem is still in its infancy, just as our appreciation of the factors underlying the etiology of ulceration is still adolescent, will be agreed by all. As a reminder of how recent is the development of our ability to diagnose the condition, you may recall that “deformity of the bulb outline” was established as a sign of ulcer only in the year 1914, when L. G. Cole published his paper in the Lancet. Of course, many previous efforts had been made to diagnose both gastric and duodenal ulcer. Schmieden and Härtel, in 1902, published a paper on roentgen examination in surgical diseases of the stomach. Hemmeter, in 1906, tried to demonstrate the site of ulceration by a residual fleck of bismuth. Reiche, in 1909, was able to demonstrate the cavity of the ulcer by the Rieger meal. And Haudek, in 1910, for the first time clearly described the typical roentgen sign of penetrating ulcer, namely, the niche. Two years later he published a paper on the radiological diagnosis of duodenal ulcer. Baron and Barsony also published a paper on that subject in 1912. To these writers and to G. Holzknecht, who did much of the pioneer work on the normal roentgen appearances of the gastrointestinal tract, belongs the credit for the simplification, or even elucidation, of the diagnosis of peptic ulcer. Later investigators, von Bergmann, Chaoul, Akerlund, Carman, and Forssell, among others, have added considerably to our information. Before passing on to the pathology and diagnosis of ulceration it may be entertaining to recall a few lines from Beck's textbook on “Roentgen-ray Diagnosis and Therapy,” published in New York in 1904. In dealing with the roentgen examination of the abdominal region (peptic ulcer, as such, is not mentioned), he observes that the gastric outline may be mapped out by filling the viscus with salts, such as subnitrate of bismuth, or gases, such as carbonic acid and air; but states, however, that “the introduction of a soft rubber tube, the lumen of which is filled with mercury, is preferable,” or the use of a rubber tube containing a spiral wire “as designed by myself.”1 “The stoppage of the tube indicates its arrival at the large curvature, and, in selected cases (especially in children), the motions of the spiral wire may be studied by the aid of the screen.” (One wonders if our present methods of examination will not seem equally archaic twenty-five years hence.) Pathologically, duodenal ulcer may be divided into various types, depending on whether one wishes to use a strictly histologic, a medical, a surgical, or a roentgenologic basis.