Blood may appear in the stools under several conditions, such as the presence of hemorrhoids, of ulceration, of the hemorrhagic diathesis, the rupture of an aneurysm, etc., and while the source of the hemorrhage may at times be' obscure, the recognition of the blood is as a rule not difficult. A possible source of error is, however, pointed out by Carter1, who reports three cases, one of chronic valvular disease, febrile toxemia and acute cystitis, one of typhoid fever, and one of acute pneumonia, in which the intestinal discharges, while in general golden brown in color, presented streaks of a bright-red color, which became intensified on standing and exposure to air. Careful examination, however, proved the discoloration not to be due to blood, nor to biliverdin or bilirubin, but to a substance closely related to stercobilin, the normal coloring matter in feces.