THE INTERNAL SECRETION OF THE PANCREAS 491 



HO/\CH. OH. CH 2 NH. CH, 



This compound is the active principle or hormone of the epinephros. Epi- 

 nephrin is now prepared synthetically and commercially, and is an important 

 and useful medicinal product. 



b. Secretory Nerves for the Adrenals. Dreyer was first to give evidence 

 that the products of this gland are discharged into the blood of the adrenal 

 vein in increased quantity on splanchnic stimulation. Cannon has exten- 

 sively studied the relation of the secretion of epinephrin to the autonomic 

 reactions of the body. His evidence indicates that during fright, anger, 

 etc., which in animals is accompanied by vigorous activity of the mechanisms 

 innervated through the automatic system, the suprarenal glands are strongly 

 stimulated. The result is a production and discharge of an increased amount 

 of epinephrin into the circulation. As the nervous mechanisms tend to 

 fatigue the increase in the secretion of epinephrin brings about a hormone 

 stimulation supplementing and strengthening the nerve control during this 

 critical time. 



This gland furnishes, on the whole, most conclusive and typical evidence 

 of the presence of an internal secretion that is absolutely necessary to the 

 normal metabolism of other organs. 



c. Epinephrin in Relation to Carbohydrate Metabolism. The action of 

 the hormone, epinephrin, which seems so specific in relation to the function 

 of special types of nerve endings is bound up with the metabolism of carbo- 

 hydrates. Following the removal of the suprarenal glands the store of gly- 

 cogen in the liver is quickly discharged and glycogenesis is no longer possible. 

 This has been shown by removing the suprarenals in rats which stand the 

 operation more readily than most animals, if the glands are removed in 

 successive operations. 



The Internal Secretion of the Pancreas. Minkowski and von 

 Mering have shown that total extirpation of the pancreas is followed in all 

 cases by the appearance of sugar in the urine in the course of a few hours. 

 The amount of sugar which appears is considerable, from 5 to 10 per cent. 

 This experimental disease is accompanied by an increase in the quantity of 

 urine and by abnormal thirst and appetite. It proves fatal in fifteen days or 

 less. These results are obtained only when the entire gland or more than 

 nine-tenths of it have been removed. If one-tenth or more of the gland be 

 left behind, sugar appears in the urine when carbohydrates are eaten, but not 

 otherwise. Nor is it necessary that the remaining portion of the gland be in 

 its normal situation. Successful grafts of pancreas under the skin of the 

 abdomen or elsewhere will prevent the appearance of sugar in the urine and 

 the other symptoms. If, however, the graft be subsequently removed, the 

 sugar in^the urine and the other symptoms reappear, and the experimental 



