“…Radioactive labelling of blood corpuscles in connexion with the intubation technique has been recommended for determining the site of gastrointestinal bleeding (Ebaugh, Clemens, Rodnan, and Petersen, 1958;Pillow, Hill, Ragen, Siemsen, and Walker, 1962), but it is difficult to see its advantage for this purpose, though it can certainly help to ascertain the magnitude of the haemorrhage (Gerritsen, Heinz, and Stafford, 1954;Bannerman, 1957;Roche, Perez-Giminez, Layrisse, and Di Prisco, 1957).…”