In the course of our clinical study of ulceration of the esophagus, it was evident that, up to the present, insufficient attention has been directed to this disease, which according to our experience is more common than has ordinarily been reported in the literature. On this account, an attempt was made to determine experimentally certain important diagnostic problems associated with this condition. In our experiments, nineteen dogs were utilized. The dog is a favorable subject for experimental study of this disease, as ulcerations can be produced with but slight difficulty following which x-ray and esophagoscopic examinations can be readily performed. The following types of ulcerations were produced: (1) mucosal lesions; (2) penetrating ulcers; (3) perforating ulcers. METHOD OF PRODUCTION OF ULCERS As our study of ulcerations of the esophagus was undertaken primarily with the object in view to clear up certain questions in diagnosis, it made but slight difference as