BILIARY AND INTESTINAL SECRETIONS. 241 



tion or in the amount of calcium salts present. All the 

 accelerating effects of bile upon the lipolytic activity of 

 pancreatic juice can be equally well produced by the ad- 

 dition of lecithin. This is shown very well in the follow- 

 ing table, in which is indicated the number of cubic cen- 

 timeters of a 1/20 normal alkali solution which were required 

 to neutralize the acid formed in twenty-four hours in three 

 tubes containing the same amounts of pancreatic juice and 

 triacetin. 



Pancreatic juice+ triacetin = 4.3 c.c. 



Pancreatic juice + triacetin + 2 c.c. bile =19.5 c.c. 



Pancreatic juice + triacetin + 2 drops alcoholic solution of 



lecithin =19.9 c.c. 



Commercial bile salts also accelerate the action of pan- 

 creatic juice on triacetin, but when these salts are purified 

 they lose this power, which seems to indicate that the action 

 of the crude preparation is determined solely by its con- 

 tamination with lecithin. 



As to the manner in which the bile assists the lipolytic 

 action of the pancreatic juice, we have as yet no satisfactory 

 explanation. 



Bile also favors the action of some of the other ferments 

 contained in the pancreatic juice. But while bile may even 

 treble the velocity with which fats are digested, it only doubles 

 the velocity with which amylase will act on starch, or alkali- 

 proteinase (trypsin) on proteins. 



Aside from its action as an aid to the pancreatic ferments, 

 bile has yet other, though perhaps scarcely as important, 

 functions. While a large number of the fatty acids are freely 

 soluble in water, this is not true of the fatty acids derived 

 from most of the fats (stearin, palmitin, olein) which consti- 

 tute our food. MOORE, ROCKWOOD, and PFLUGER'S l studies 



1 MOORE and ROCKWOOD: Journal of Physiology, 1897, XXI, p. 58. 

 FFLUGER'S numerous papers on fat are contained in Pfliiger's. Archiv, 

 Vols. LXXX to LXXXVI (1900 to 1901). 



