Lest any one misapprehend the purpose of this paper, let it be said at the outset that what follows is not designed to be a defense of the roentgenologic method or an apology for its shortcomings. Neither is needed, for the general efficiency and reliability of roentgenologic examination in disclosing and identifying cancer of the stomach cannot be impugned, and it is safe to say that no practitioner of modern medicine would consider any diagnosis or exclusion of cancer to be complete and convincing without the roentgenologic opinion. Yet there are real errors, such as failures to discover lesions or to predict their true character, and apparent errors, which in fact are only misunderstandings as to the implications of certain roentgenologic reports. Although the proportion of these actual and fancied lapses is not large, they are sometimes made the basis of expressed or implied criticism that from the viewpoint of