Templeton, Marcovich, and Heinz (1) stated that the only reliable x-ray evidence for active duodenal ulcer is the ulcer niche or crater, and they described the compression technic for its demonstration. By means of fluoroscopy and spot films of outstanding quality, they were able to demonstrate a crater in a high percentage of cases regarded as active on careful clinical study. Most craters occurred on the anterior or posterior wall remote from the greater or lesser curvatures, where they would be obscured by barium unless effective compression could be applied. In some patients, particularly of the sthenic type, the duodenal bulb will lie high beneath the ribs or in a posterior position where it cannot be compressed. Occasionally, also, marked abdominal muscle guarding will prevent effective compression. Sosman (2) said that he was unable to compress the bulb in 15 to 20 per cent of the patients whom he examined. Craters may sometimes be recognized following evacuation of the bulb by peristalsis, but suc...