It is proposed in this investigation chiefly to discuss the value of the fractional test -meal as an aid to diagnosis. Reference is also made to the relationship of the chemical findings to the symptoms and to the line of treatment - indicated in certain cases. The fractional test -meal findings in 100 cases of organic disease of the stomach and duodenum are given in detail. In each case the diagnosis was confirmed either by operation or at post -mortem. The cases have been placed in three sections according to the lesion: 1. Duodenal Ulcer; 2. Gastric Ulcer; and 3. Carcinoma of Stomach. The fractional test -meal findings in the above groups are tabulated at the end of each section. The test -meal charts are reproduced in all cases, with the essential details of the case notes attached. in 33 cases post -operative charts are given also.