THE PANCREATIC JUICE 



749 



A. Secretin juice from three dogs. Sp. gr. 1014. 



B. Secretin juice, specimen collected at beginning (a), and at end (6). 



C. Pilocarpine juice. 



tion proceeds. The concentrated juice obtained by injection of pilocarpine, 

 which may contain as much as 6 per cent, total solids, is always considerably 

 less alkaline than the more dilute juice got by injection of secretin. The 

 most interesting and important constituents of the juice are its ferments 

 or precursors of ferments. The juice on arrival in the intestine has, or 

 develops, an effect on all three classes of foodstuffs, namely, proteins, fats, 

 and carbohydrates, due to the presence of distinct ferments, viz. trypsin, 

 steapsin or lipase, and amylopsin. 



ACTION ON PROTEINS 



Although the digestive action of pancreatic juice on proteins was pointed 

 out by Corvisart, little attention was paid to this effect either by Claude 

 Bernard or subsequent authorities, until Kuhne subjected the action of 

 extracts of the gland to a thorough investigation. The neglect of this 

 action by Claude Bernard must be ascribed to the fact that he worked with 

 pancreatic juice. It has been shown more recently that pancreatic juice as 

 secreted is free from proteolytic effects, and that for the development of this 

 power it is necessary that some change should be brought about in the juice 

 itself, namely, a conversion of trypsinogen into trypsin. This change under 

 normal circumstances is brought about directly the juice enters the gut, by 

 the action of a substance enterokinase contained in the succus entericus. 

 The pancreatic juice thereby acquires a proteolytic activity superior to that 

 of any other digestive juice, so that the proteins of the food undergo a very 

 thorough disintegration. The different constituents of the protein molecule 

 show a varying resistance to the action of trypsin. The greater part of the 

 molecule is rapidly broken down into its proximate constituents, namely, 

 amino-acids, and the same change is undergone by the proteoses and pep- 

 tones resulting from the gastric digestion of proteins. Within a few minutes 

 therefore after the chyme has reached the small intestine, a certain amount 



