Insulin

tract to a pasty consistency. Alcohol (80 per cent.) is then added and the mixture is centrifugalised and the active principle is obtained in alcoholic solution in the clear top layer. This is pipetted off and mixed with an excess of absolute alcohol in which the active principle becomes precipitated. The precipitate is then dissolved in sterile distilled water, concentrated by distillation in vacuo, filtered through porcelain, tested for sterility and standardised. Insulin when injected into healthy animals causes a great diminution of the blood sugar accompanied by symptoms suggestive of strychnine poisoning, and the standardisation of the substance is effected by finding the amount needed to cause a definite reduction