THE PANCREATIC JUICE 753 



the disaccharide maltose into the monosaccharide glucose. The juice in 

 the gut is therefore able to effect the further digestion of the products of 

 salivary digestion. On the other disaccharides pancreatic juice is without 

 effect. It contains no invertase, nor does it, in spite of certain statements 

 to the contrary, ever contain lactase. It has therefore no effect on either 

 cane sugar or milk sugar. 



THE ACTION OF PANCREATIC JUICE ON FATS 



Fresh pancreatic juice contains a strong lipase of fat-splitting ferment, by 

 means of which, in the presence of water, neutral fats, e. g. the triglycerides 

 of palmitic, stearic, and oleic acids, are broken up into glycerin and the 

 corresponding fatty acids. This ferment is active either in alkaline, neutral, 

 or very slightly acid reaction. If the reaction be alkaline, the fatty acids 

 produced by the lipolysis combine with the alkali present with the formation 

 of soaps. The ferment may be obtained from extracts of the fresh gland, 

 but is rapidly destroyed if active trypsin be present. It is also contained in 

 some of the dried commercial preparations of trypsin. It is apparently 

 insoluble in distilled water, and is therefore found in the residue after extract- 

 ing these commercial preparations with water. It is easily soluble in glycerin. 

 The velocity with which lipolysis occurs is much increased (four to five times) 

 by the addition of bile. This adjuvant action of bile is not destroyed by 

 boiling, and is due entirely to the bile salts. These act in two ways. In 

 the first place, by their physical qualities they diminish the surface tension 

 between water and oil, so enabling a closer contact to be effected between 

 the watery solution contained in the juide and the oil which is presented 

 to it. Moreover they may aid in the solution of the ferment itself. In the 

 second place, bile salts have a solvent action on soaps as well as on fatty 

 acids in slightly acid medium. Bile may be regarded therefore as a favour- 

 able excipient or medium for the interaction of the lipase and the neutral 

 fats. The lipase of pancreatic juice will also hydrolyse the esters of the 

 fatty acids, such as ethyl butyrate or monobutyrin. On the phosphorised 

 fats or phosphatides, such as lecithin, its action is still a subject of doubt. 

 According to certain authors extracts of the pancreas have the power of 

 splitting off choline from lecithin. It is not known whether the same 

 property is present in pancreatic juice itself, or whether any other dissocia- 

 tions are brought about in the complex molecule of lecithin under the action 

 this digestive fluid. 





THE SECRETION OF PANCREATIC JUICE 



In order to study the relation of the secretion of pancreatic juice to the 

 other processes of digestion, observations must be carried out on an animal 

 with a permanent pancreatic fistula. 



Such a fistula was established by Claude Bernard by bringing the duct of the pancreas 



to the surface and inserting into it a lead or silver tube. The arrangement was 



unsatisfactory, since after a few days the tube dropped out and the natural ' course of 



the duct from pancreas to intestine was restored. In order to avoid the disadvantages 



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