106 PHYSIOLOGY. 



Any disturbance to these functions is felt, not only in the gland 

 itself, but throughout the entire body, since then its metabolism is 

 disturbed. Thus is very clearly established one other instance show- 

 ing the intimate relation that each and every organ or part bears to 

 the general mechanism of the entire body as a unit, and the conse- 

 quent general disturbances following its disease. 



The transfusion of diabetic blood into a normal animal fails to 

 produce within the recipient any diabetic symptoms. From this we 

 learn that there was no accumulation in the blood of poisonous matter 

 which the pancreas was supposed to remove. From the facts noted it 

 is apparent that removal of the pancreas produces diabetes, not from 

 any influence upon surrounding sympathetic ganglia or hindrance 

 to passage of its secretions into the intestinal canal, but is caused by 

 the removal from the system of something, which something pos- 

 sesses powers aside from those employed in digestion. The salivary 

 glands, whose structure is similar^ to that of the pancreas, when re- 

 moved givo no untoward results. When the structures of these two 

 glands are minutely and carefully examined, it is found that there is 

 but one difference : in the parenchyma of the pancreas there are pres- 

 ent little cells, of Langerhans, epithelial in appearance, richly 

 supplied with blood-vessels, but having no connection with the alveoli 

 or ducts of the gland. 



Cohnheim found a body in the pancreas which he calls the acti- 

 vator, which resembles an internal secretion like adrenalin. When 

 this activator is added to muscle-extract, it breaks up the sugar in the 

 blood. Consequently the removal of the pancreas or its activator lets 

 the sugar appear in the urine. Seventy-five grams of muscle and 

 about .08 gram of pancreas are the best proportions to destroy the 

 greatest amount of glucose. The pancreatic activator is not injured 

 by boiling, and is soluble in alcohol, which facts show that it is not 

 a ferment. It is now believed that there is some internal secretion 

 manufactured by these patches of Langerhans cells in the pancreas, 

 which is a very powerful factor in the disintegration of carbohydrates, 

 but whose removal allows the abnormal production in the blood and 

 urine of dextrose. According to several observers, the islets of 

 Langerhans are not independent structures of separate origin, but 

 are formed by certain definite changes in the arrangements of the 

 secreting cells of the pancreatic tissue. Secretin exhausts the pan- 

 creatic cells, and thus converts the greater part of the secreting tis- 

 sue into islet tissue. 



The embryological evidence furnished by Laguesse and Dale 



