_Manufacture and sale._--One of the unusual aspects of the insulin discovery was the method of control in its sale. The discoverers did not wish to profit unduly by their work, but they were anxious that its manufacture and application on a large scale be scientifically controlled. Arrangements were therefore made to have it manufactured under accurate supervision in the United States by the Eli Lilly Company, and in Canada by the Connaught Laboratories, and more recently in certain other home and foreign laboratories. The process of manufacture is an interesting one. The Islands of Langerhans constitute a small portion of what is relatively a small gland. In stock yards and packing houses this gland is called sweet breads; the sweet breads served under glass in the restaurants are usually the pancreas of the sheep or hog, since these are small. The beef pancreas is a much larger organ, weighing about a pound or a pound and a half. The method devised by Collip for obtaining insulin from the pancreas involves repeated extraction of the ground-up pancreas with alcohol, in order to remove the unnecessary tissue substances. When this is done on a small scale in the chemical laboratory, there is, of course, considerable wastage of raw material and of substances used in the extraction. The application of the matter on a commercial scale involved additional problems. They were not only overcome successfully, but continued improvements have made possible the provision of the life-saving remedy at a reasonable price. _Juvenile diabetes._--One of the most striking effects of the work was the result of the use of the remedy in the diabetes of children, or juvenile diabetics. This condition had previously been considered invariably fatal. Now the child may be treated satisfactorily, and it seems possible that its development under the influence of the drug may permit a gradual lowering of the dosage to amounts that may be administered with little expense or difficulty. After the investigators had completed the trials of the preparation in their own hospital, plans were made for extensive clinical investigation in other institutions in which there were men capable of conducting scientific studies on diabetes. More than 50 institutions were utilized in order to give the drug the most complete possible scientific trial before offering it to the medical profession in general; and when at last these trials were completed and the co-operating manufacturing concerns had fully developed the machinery for production of the drug on a large scale, it was released to the medical profession throughout the world.