OUR studies in connexion with insulin led us to the conception that carbohydrate metabolism is performed by an oxidising ferment mechanism. This theoretical conception induced us to test vegetable material, known to contain oxidases and peroxidases, for oxidising substances having an insulin-like action. In December 1922 we injected 5 c.c. of juice from a new potato intravenously into a 1500 gm. rabbit and noted a fall of blood sugar in one hour from 0.17 to 0.13 per cent. Since then we have found that sterile pieces of raw potato, and juice expressed from these, introduced into a glucose solution, after incubation for twenty-four hours at 37° C., caused this to lose from 26 to 36 mg. of glucose per 100 c.c. These results were published in the Jour. Amer. Med. Assoc., June 2, together with results indicating a diminished glycolytic power of blood from diabetics.