966 THE INTERNAL SECRETIONS 



of only a part of this organ does not produce these symptoms, nor do 

 they appear if a portion of its tissue is transplanted. The latter 

 procedure usually consists in grafting its processus uncinatus and cor- 

 responding blood-vessels under the skin of the abdomen. It has also 

 been established that the ligation of the ducts of the pancreas does not 

 produce a permanent glycosuria, but only those syraptoms which are 

 commonly associated with a loss of the pancreatic juice. 



The Function of the Internal Secretion of the Pancreas. — The 

 fact to be derived from the preceding data, is that, in addition to its 

 digestive juice, the pancreas also produces an internal secretion which 

 is absolutely essential to the life of the animal. While the evidence is 

 not absolutely conclusive, it is surmised that this internal secretion 

 arises in the cells of the islets of Langerhans. This assumption is 

 strengthened somewhat by the statements of Opie^ and others that 

 these cells show signs of hyaline degeneration and atrophy in persons 

 who have died of diabetes mellitus. The correctness of this observa- 

 tion, however, has recently been questioned. ^ Nothing definite is 

 known regarding the cause of this disease, although it is supposed that 

 it develops in consequence of a disturbance of the carbohydrate 

 metabolism. Regarded from a very general standpoint, the conditions 

 leading to glycosuria, may be classified under the following headings: 



(a) Alimentary; too copious an absorption of sugar is frequently followed by 

 a temporary excretion of this substance in the urine. This condition is known as 

 alimentary or physiological glycosuria. It subsides as soon as the body has suc- 

 ceeded in ridding itself of the excessive amounts of sugar absorbed. 



(6) Pancreatic; a disorder in the internal secretory power of the pancreas is the 

 cause of this form of glycosuria. 



(g) Hepatic; the cells of the liver do not exercise their storative functions 

 properly, and allow too large an amount of sugar to escape into the blood. 



(d) Oxidative; the cells of the tissues are unable to oxidize the sugar, because 

 they lack the agent which is required to accomplish this reduction. The latter 

 may be conveyed to them from the pancreas or may be a product of their own. 



(e) Renal; the cells of the kidney have lost their relative impermeability and 

 allow the sugar of the blood to pass more readily through them. 



Since in the present instance we are solely concerned with the pan- 

 creatic type of diabetes, this problem may be restricted in the following 

 way: The pancreas furnishes an active principle, possibly an enzyme, 

 which aids in the hydrolysis or oxidation of the sugar in the tissues. 

 In the absence of this agent, this process remains incomplete and 

 the sugar escapes into the urine. In this case, therefore, the internal 

 secretion of the pancreas acts in the manner of a hormone, i.e., as 

 a stimulus to cellular activity. Another view is that the pancreas 

 furnishes an active principle which regulates the sugar output of the 

 liver. In the absence of this agent, the cells of the liver convert 

 their glycogen too rapidly, thereby increasing the sugar content of 

 the blood and producing a hyperglycemia which is soon followed by a 



1 Jour. Exp. Med., v, 1901, 397. 



2 Vincent and Thompson, Jour, of Physiol., xxxiv, 1906. 



