Art. XV. — Experiments on the Range of Action of the 



Digestive Ferments. 



By James Jamieson, M.D. 



[Bead November 5, 1887.] 



No subject in the whole range of physiology has had more 

 attention given to it, than that of digestion. Especially 

 since Dr. Beaumont published the results of his observations 

 and experiments on St. Martin, there has been almost an 

 uninterrupted series of investigations into the properties of 

 the digestive juices, and the ferments contained in them. 

 But in spite of the excellent work done, there are still points 

 left unsettled, this being true especially of the active con- 

 stituents of the pancreatic juice. It has long been known 

 that the pancreas forms a secretion possessed of very 

 powerful digestive properties, and these of a very mixed 

 kind. It has been proved to be capable of digesting all 

 three of the chief ingredients of food, viz., the albumens, the 

 fats, and starch, though there has not been much progress 

 made in the direction of isolating, in a pure state, 

 the ferments which exert these actions. Pancreatine, or 

 pancreatic extract, is assumed to contain at least three 

 distinct ferments — trypsin, the solvent of albuminous sub- 

 stances ; steatopsin, that which emulsifies fats, and splits 

 them up into their constituents ;- and amylopsin, the ferment 

 which converts starch into sugar. Of these, onty the first 

 has been obtained in the separate state, and in a tolerably 

 pure form ; but of them all it is known, that they exert 

 their special actions best, if not only, in alkaline or neutral 

 media. The pancreatic juice itself is alkaline in reaction, 

 and complete neutralisation of the acid contents of the 

 stomach, when poured into the small intestine, is secured 

 by the further help of the bile which is also strongly 

 alkaline. But, while it has been sufiieieutly shown that 

 the pancreatic secretion, in the fresh state or in the form of 

 an extract, does convert starch into sugar, and albumen into 

 peptones, in an alkaline mixture, there has been almost no 

 exact enquiry into the influence exerted on it by acidulation 

 of the media in which it may be called upon to act. And 



