272 DIGESTION. 



and has a distinctly alkaline reaction. Bernard found the specific gravity of the fluid 

 from the dog to be 1040. The quantity of organic matters which the normal secretion 

 contains is very great, so that the fluid is completely solidified on the application of heat. 

 This great coagulability is one of the properties by which the normal fluid may be distin- 

 guished from that which has undergone alteration. 



Composition of the Pancreatic Juice of the Dog. (Bernard.) 



Water , 900 to 920 



Organic matters, precipitable by alcohol and containing ) 

 always a little lime (pancreatinc, trypsine, etc.) \ ' ' 



Carbonate of soda, 1 



Chloride of sodium, 10 to 6'40 



Chloride of potassium, I 



Phosphate of lime, J 1,000 1,000 



f 



Most of the analyses which have been made of the pancreatic fluid are not to be relied 

 upon, as the manner in which the juice was obtained shows generally that it was not 

 normal. There is no doubt, however, that the fluid which was obtained from the dog 

 and analyzed by Bernard possessed all of its characteristic physiological properties. 



The chemical properties of the organic principles of the pancreatic juice are distinctive. 

 Although, like albumen, they are coagulated by heat, the strong mineral acids, and abso- 

 lute alcohol, they differ from albumen in the fact that their dried alcoholic precipitate can 

 be redissolved in water, giving to the solution all the physiological properties of the nor- 

 mal pancreatic secretion. Bernard has also found that they are coagulated by an excess 

 of sulphate of magnesia, which will coagulate caseine but has no effect upon albumen. 

 It is important to recognize this distinction between the organic matters of the pancreatic 

 juice and other nitrogenized principles, especially albumen, from the fact that the last- 

 named substance has the property of forming an emulsion with fats, though not so readily 

 and completely as the pancreatic juice ; and it is essential to decide whether the organic 

 principles be peculiar and distinct substances, or albumen transuded pathologically, per- 

 haps, from the blood. There can be no doubt, in view of the marked chemical and physi- 

 ological peculiarities of pancreatine and trypsine, that they are distinct proximate princi- 

 ples, characteristic of the pancreatic secretion and found in no other fluid. 



Researches have shown that pancreatine and trypsine are essential physiological 

 constituents of the pancreatic juice, giving to this fluid its peculiar digestive properties. 

 The contents of the duodenum, as the partly digested matters pass from the stomach, are 

 generally acid; but this does not at all interfere with the action of the pancreatic juice. 

 Although the secretion itself is alkaline, it retains its physiological properties when it 

 has been rendered acid by admixture with gastric juice. 



The inorganic constituents of the pancreatic juice do not possess any great physiologi- 

 cal interest, inasmuch as they do not seem to be essential to its peculiar digestive proper- 

 ties. It has been shown, indeed, by Bernard, that the organic principles alone, extracted 

 from the pancreatic juice and dissolved in water, are capable of imparting to the fluid all 

 the physiological characters of the normal secretion. 



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

 variously estimated by different authors. After what has been said concerning the varia- 

 tions to which the secretion is subject, it is not surprising that these estimates should 

 present great differences. Bernard was able to collect from a dog of medium size from 

 eighty to one hundred grains in an hour ; but it must be remembered that only one of the 

 ducts was operated upon, and that the gland is always very susceptible to irritation. 

 There is no accurate basis for an estimate of the quantity of pancreatic fluid secreted in 

 the twenty-four hours in the human subject, or of the quantity necessary for the digestion 

 of a definite amount of food. 



