It would appear to be fairly well established that no actual intensification of shadows on the X-ray plate need be looked for, despite the result of the experiment described on page 35 et seq., by the process of surrounding an organ with gas. What is obtained, however, by this means is a demarcation of the edge of such an organ, where the edge would, on account of close apposition to, or overlapping with, other structures of equal or greater density, have been lost. Any value that the method possesses as a clinical/diagnostic measure is dependent on this factor. We are thereby enabled :- • a. To judge of the shape, contour and size of the organs • b. To locate them in cases where their position is abnormal • c. To recognise various pathological processes. The difficulties connected with the radiographic demonstration of the liver and spleen in their entirety, have hitherto almost been insuperable , and pathological conditions affecting their parietal surfaces have perforce remained obscure. Splenic enlargement needed to be very considerable in extent before indisputable evidence to that effect could be read from a skiagram. This difficulty, it may be claimed with justice, has been solved to a large extent by the method of gas inflation of the peritoneal cavity. The diagnosis of a number of pathological processes, dependant on a delineation of one or other of these organs, has been simplified. The clear picture obtained of the subphrenic space and diaphragm leads to the confident expectation of progressing the recognition of diseases of this difficult region. The claims of various American authors notwithstanding, the positive diagnosis of gall stones and gall bladder. disease would seem to have made disproportionately slow progress. The shadows of the stones , if present , tended to be so faint that they were generally lost in that of the liver, especially if the confusing effects of gas in the intestine were superadded. The viscus itself could seldom be shown on the plate, unless very markedly altered by disease. The inflation method is of undoubted value in assisting to render visible the gall bladder . Indeed it may be stated that, with proper technical precautions, the normal viscus should generally be seen on the plate . With the field thus confined by the delineation of the gall bladder, gall stones should be seen in a larger proportion of cases. Adhesions to surrounding organs,. with consequent deformation, is often recognised when present. While the method is of use in the investigation of cases in which the actual position of a kidney, difficult to make up with the ordinary method, has to be determined, it does not appear to be of much value in the demonstration of urinary calculi generally. When the kidney outline is discernible, nothing is to be gained by inflation. Neither can the ureter be shown, and the bladder is easily filled with gas per urethram, if necessary for radiographic purposes. While it is certain that the female generative organs and tumour growths in the pelvis are capable of demonstration with this method, no special advantages can be claimed for it as compared with the ordinary clinical methods of investigation of these cases. In dealing with the digestive tract also, the clinician would be better served by the use of the opaque meal method. The walls of the stomach and colon can certainly be rendered visible if these portions of the tract are separately inflated in combination with peritoneal distension, but it is open to grave doubt if any information of real value would be gained. There is no evidence to support the expectation that carcinoma of the large intestine would be rendered manifest at an earlier stage than otherwise. The scope of the usefulness of the method may be summed up as comprising :- 1. Lesions of the diaphragm, subphranic space, liver and spleen, where the zone of separation produced by the gas reveals the whole of such area or organ. • 2. Gallstones and other gall bladder lesions, in which the fact that the size and form of the viscus can be studied often provides data of great diagnostic significance. • 3. The determination of the exact position of the kidney, in doubtful cases. • 4. Abdominal tumours, the anatomical relationships of which can often be traced. • 5. Adhesions of the viscera to the parietal peritoneum. Finally, while the method is not at present recommended as a routine procedure, and its indiscriminate use in cases of intra-abdominal disease is to be deprecated, it must be conceded that it records an undoubted advance in radio -diagnosis.