_Removal of pancreas causes diabetes._--Minkowski was studying digestion and it happened in the course of certain investigations, that it became necessary to operate on a dog and remove this organ. A few days later it was noticed that flies were attracted in great numbers by the urine of this dog. The urine was examined, and the reason for the flies and the relation of the pancreas to diabetes was at once apparent. The urine contained sugar. Another animal was operated on, the pancreas removed and diabetes followed. Cats, swine, and frogs were then experimented with. In every case, complete removal of the pancreas resulted in severe diabetes, while partial removal caused a more chronic and milder diabetes. _The islands of Langerhans._--Previously, in 1869, Paul Langerhans, described peculiar clumps or islands of cells which differ in appearance from the bulk of the tissue in the pancreas. In 1890, Scobolew and Schulze showed that if the ducts leading from the pancreas were tied off, the islands withstood the destruction that was wrought in the rest of the organ by backing up of the pancreatic secretions. Animals treated in this manner did not develop diabetes, and it was concluded, therefore, that it was the islands that manufactured the anti-diabetic material of the pancreas. The name “insulin” was suggested for this material in 1916 by an Englishman, Shafer. _Previous attempts to obtain insulin._--In the meantime, efforts were being made by numerous scientists to extract from the pancreas the anti-diabetic principle. Some of these attempts nearly succeeded. Many of them failed because it was not known then that insulin is rendered inactive when it is given by mouth and subjected to the disintegrating action of the juices in the digestive tract. Innumerable attempts were made to control diabetes by feeding either fresh pancreas, or pills and pellets manufactured from the pancreas. Thus far, all such efforts have been in vain, and yet various drug companies continue to sell pancreatic pills as diabetic remedies. The results obtained by grafting pieces of pancreas into dogs previously made diabetic by the removal of the pancreas have been more successful. The experimental diabetes of animals so treated can be controlled, but such procedures offer nothing to mankind, because grafts made from a lower animal to man invariably atrophy, that is, shrink up and disappear.