THE BILE. 155 



The enterokinase has not yet been obtained as such ; it is precipi- 

 tated from extracts of the intestinal mucosa in impure form by 

 means of acids. It closely adheres to any precipitated nucleo- 

 proteids. 



Delezenne states that he has demonstrated the presence of entero- 

 kinase also in the leucocytes of the blood, and he explains the diges- 

 tive action of supposedly inactive pancreatic juice upon fibrin with- 

 out an extra addition of enterokinase on the basis of the presence of 

 leucocytes carrying enterokinase, contained in the meshes of the 

 fibrin or in the pancreatic juice. The same writer claims to have 

 found enterokinase in bacteria, in various fungi (Amanita), and in 

 snake-venom. 



Erepsin. (This is considered in the section on Resorption). 



Secretin and Prosecretin. According to Bayliss and Starling, 

 it is possible to extract a substance from the mucosa of the duodenum 

 and jejunum with dilute acids (4 percent, hydrochloric acid), which 

 when introduced into the circulation causes a secretion of pancreatic 

 juice. Substances of this order Bayliss and Starling term hormones. 

 The hormone in question is known as secretin, and is supposedly 

 formed by the acid from an inactive product, the prosecretin, which 

 exists as such in the cells. When once formed (activated) it retains 

 its activity even upon neutralization and alkalinization. It is not 

 destroyed by boiling in either acid, neutral or alkaline solution, and 

 can hence not be a ferment. 



Camus has ascertained that while secretin can be obtained with 

 various organic and inorganic acids (not with boric acid or carbonic 

 acid), a more active preparation is obtained with hydrochloric acid, 

 nitric acid, and sulphuric acid than with other acids. 



Aside from its action upon the pancreatic cells secretin is also 

 said to increase the secretion of bile and saliva. Atropin and an- 

 aesthethics, notably chloroform, diminish its activity. 



Popielski has recently found that secretin can also be obtained 

 from the mucosa of the rectum, the ileum, the stomach, and that it 

 can even be isolated from the arterial blood. It appears, moreover, 

 from his researches that the body has not only a specific action so 

 far as the pancreatic cells are concerned, but that on intravenous or 

 hypodermic injection it stimulates nearly all digestive glands to 

 activity. These results have not yet been confirmed. 



THE BILE. 



Formerly it was supposed that the bile played an important part 

 in the process of digestion, and was further capable of control- 

 ling the intensity of the putrefactive and fermentative processes 

 which even normally take place in the lower intestinal tract. 

 It has now been established, however, that, aside from its emul- 

 sifying action upon fats, the secretion possesses no digestive prop- 

 erties whatever, and is likewise without effect upon the bacteria 



