The probability that the pancreas furnishes more than one internal secretion to the organism was suggested by the discovery of more than one type of cell in the islets of Langerhans. The evidence that insulin is elaborated by the beta cells of the islets is now fairly conclusive. The function of the alpha cells remains unknown. In 1924 Fisher1 and Allan, Bowie, Macleod and Robinson2 demonstrated that completely depancreatized dogs could not be maintained alive for long even though adequately treated with insulin. At death the most obvious change observed was an extensive fatty infiltration and degeneration in the liver. In one experiment, however, Fisher noted an extreme degree of arteriosclerosis of the aorta. The addition of raw pancreas to the diet was found by Macleod and his associates to prevent the development of these changes in the liver and to permit survival for long periods of time.