BILIARY AND INTESTINAL SECRETIONS. 245 



as normal intestinal juice. For this we need the cooperation 

 of the circulating blood, from which are taken the substances 

 which either directly or after they have been changed into 

 new chemical compounds through the activities of the mucous 

 membrane go to make up the intestinal juice. 



Stimulation of the vagus nerve in the neck or below the 

 diaphragm seems not to affect the secretion of enteric 

 juice. Removal of the cceliac or mesenteric plexuses seems 

 to bring about an increased secretion similar, perhaps, to 

 the ordinary paralytic secretion but not so great in amount. 

 If certain of the ganglia are left behind, the secretion may 

 not take place. 



Attention has already been called to the fact that the 

 intestinal juice has not the same chemical composition through- 

 out its entire length. Special mention must be made of the 

 secretion of the duodenum. In addition to the glands of 

 LIEBERKUHN found throughout the whole of the small intes- 

 tine the duodenum contains the glands of BRUNNEB. His- 

 tologically these resemble the glands of the stomach. The 

 debate which has long been carried on as to whether the 

 proteolytic ferment found in the duodenal juice is acid- or 

 alkali-proteinase, or amphoproteinase can be looked upon as 

 decided through ABDERHALDEN'S work. While it is impossible 

 under certain circumstances to say whether we are dealing 

 with pepsin or trypsin when a fluid containing one or both 

 of them is allowed to act on fibrin or any other complex pro- 

 tein, it is possible to do this when polypeptides are used. Al- 

 kali-proteinase will split certain polypeptides not affected by 

 acid-proteinase and vice versa. In this way it has been possi- 

 ble to prove that the proteolytic powers of the duodenal juice 

 are due to acid-proteinase (pepsin) secreted by the glands of 

 BRUNNER. As is universally the case, the proteolytic fer- 

 ment of the duodenal juice is also accompanied by a milk- 

 curdling ferment. As a whole, therefore, the duodenal juice 

 is very like gastric juice, yet the physiological importance 

 ., cf the latter when compared with the former is not great. 



