2i8 INTESTINAL DIGESTION 



sary to go into the technical details of this operation, and it is sufficient 

 to say that he succeeded in maintaining an open communication -with 

 the duodenum at the site of the opening of the principal pan- 

 creatic duct and secured normal pancreatic juice in considerable quan- 

 tity. The liquid thus obtained is viscid, slightly opalescent and has 

 a strongly alkaline reaction. Bernard found the specific gravity of the 

 pancreatic juice of the dog to be 1040. The normal secretion from 

 a temporary fistula in a dog has been observed with a specific gravity 

 of 1019 (Flint). The quantity of organic matters in the normal juice is 

 very great, so that the liquid is solidified by heat. This coagulability 

 is one of the properties by which the normal secretion may be distin- 

 guished from that which has undergone alteration. 



COMPOSITION OF THE PANCREATIC JUICE OF THE DOG (BERNARD) 



Water '*' * , ' 900-920 



Organic matters, precipitable by alcohol and containing always 



a little lime (amylopsin, trypsin, steapsin) > - * _ lf . 90-73.60 

 Sodium carbonate 

 Sodium chloride 

 Potassium chloride 

 Calcium phosphate 



10- 6.40 



1000 1000 



An enzyme, almost if not quite identical with ptyalin, may be extracted 

 from the normal juice by nearly the same processes as those employed 

 in the isolation of the active principle of the saliva. On account of 

 its vigorous action on starch this substance has been called amylopsin. 



Trypsin is an enzyme capable of acting on the proteids, changing 

 them into peptones. The secreting cells of the gland produce a sub- 

 stance called trypsinogen, which is changed into trypsin. The action 

 of trypsin on the proteids is increased by the addition of small quanti- 

 ties of sodium chloride, sodium glycocholate or sodium carbonate and 

 is diminished by acids. 



A substance called steapsin, capable of decomposing fats into fatty 

 acids and glycerin, has been described as one of the organic constitu- 

 ents of the pancreatic juice. This action upon fats, which was noted 

 by Bernard, though slight, probably assists in their emulsification. 



The inorganic constituents of the pancreatic juice, beyond giving the 

 secretion an alkaline reaction, do not possess any special physiological 

 interest, inasmuch as they do not seem to be essential to its peculiar 

 digestive properties. 



The entire quantity of pancreatic juice secreted in the twenty-four 

 hours has been variously estimated by different observers. Bernard 



