In a recent issue of The Journal Greenspon1 offered an explanation of the rôle played by the gastric secretions in hematopoiesis that differs essentially from Castle's well known theory of the interaction of intrinsic and extrinsic factors. By feeding a pernicious anemia patient normal gastric juice so treated as to inhibit the action of pepsin, Greenspon states that a degree of reticulocytosis was produced which is comparable to the effect of liver therapy in pernicious anemia. It is obvious that such an experiment might easily be vitiated by the presence of "extrinsic factor" either in the stomach of the patient or in the gastric juice of the donor.
We have repeated Grenspon's experiment, adhering strictly to his technic, in five typical untreated cases of pernicious anemia. Fifteen normally healthy medical students have acted as donors of gastric juice, which in every instance has been tested for the presence of