46 STUDIES IN DIGESTION 



secretin, just as is the pancreatic secretion. No 

 bile, however, enters the duodenum except when 

 food is there, two hours after a meal. The quantities 

 of bile and pancreatic juice poured into the intestine 

 rise and fall exactly together. The reflex contractions 

 of the gall-bladder which determine this flow of bile 

 are brought about by the presence of fat or of extrac- 

 tives in the duodenum. Here probably we find the 

 explanation of any virtue which olive oil may have in 

 getting rid of gall-stones, because it is highly question- 

 able whether any of the oil is actually excreted by 

 the bile, or in any other way brought into contact 

 with the concretions so as to dissolve them. 



Of the many functions which have been charged 

 upon the bile, the most important is that of an 

 intensifier of the action of the pancreatic juice. 

 The pancreatic ferments have their activity enhanced 

 threefold in the presence of the sodium taurocholate 

 and glycocholate of the bile. Moreover, these salts 

 dissolve fatty acids, and so help in the absorption 

 of fats. 



ABSORPTION OF PROTEINS. 



There remains to be described a fundamental 

 change in our views of the digestion and absorption 

 of proteins. It was formerly taught that the gastric 

 and pancreatic ferments converted the albumin of 

 the food into soluble, diffusible bodies called peptones ; 

 that these passed through the intestinal wall into the 

 blood-stream, and in so doing were by some means 

 built up again into the proteins of the blood. Some 

 readers may recollect a Cleavage Theory, suggesting 



