Volumes of 15–50 ml of the pancreatic extract were slowly administered to dogs intravenously. Blood samples (5 mL) were collected at intervals. A significant number of dogs developed severe convulsions. In 1914 when blood glucose was measured by a newly introduced micro-method, convulsions were directly related to hypoglycemia. Blood glucose decreased by 50% or even further in most dogs (in one animal it went down to 17 mg/dL, before dying of hypoglycemia). Acute toxicity and other side effects were not present in these experiments. Control experiments (precipitation of the pancreatic extract with lead acetate) gave negative results. Similar results were achieved with glandular extracts from different animal sources [11, 12]