

THE PANCREAS 41 



internal secretion theory of the pancreas, and substitutes for 

 it a theory according to which there exist nerve centres, 

 stimulation of which determine the production of sugar, and 

 other centres of an antagonistic nature determining an internal 

 secretion of the pancreas, which internal secretion hinders the 

 production of sugar. In removing the pancreas these centres 

 are necessarily damaged, and the same happens in extirpation 

 of the duodenum or separation of the duodenum from the 

 pancreas. 



Herlitzka, working with frogs, agrees that the ganglia in the 

 wall of the duodenum are necessary for the normal internal 

 secretion of the pancreas, and agrees with the doctrine of 

 Pfluger that the correlation between duodenum and pancreas 

 is due to the action of these ganglia. 



Vahlen points out that it is usually believed that there is in 

 the pancreas a material which promotes the destruction of 

 sugar in the organism, and that this unknown substance splits 

 up the sugar in some way and thereby makes oxidation easier. 

 The author referred to has tried to isolate such a substance, 

 with entirely negative results, but he thinks he has obtained a 

 constituent of the pancreas which acts in a purely catalytic 

 manner on the vital destruction of sugar. 



Pancreatic extracts exercise an inhibitory influence on the 

 production of lactic acid in surviving muscle. 



The Islets of Langerhans 



By perhaps the majority of authors the pancreas is considered 

 to consist of two separate and distinct kinds of tissue, the 

 secreting alveoli, and the islets of Langerhans. The question, 

 however, as to the morphology and physiology of the islets of 

 Langerhans needs a little discussion. Modern writers may be 

 divided into two chief groups according to their views as to the 

 morphological significance of the islets. The first of these 

 believe that the islets are essentially of the same embryological 

 and morphological nature as the zymogenous tubules, and are 

 not to be looked upon as, in any sense, organs sui generis. The 

 second group of observers regard the structures in question as 

 definite and distinct organs, analogous to the cortex of the 

 adrenal, the epithelial part of the pituitary body, and the 

 parathyroids, and consider that they have no connection 



