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 matter 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 matter, precipitable by alcohol and containing ) 7^-An 



always a little lime (pancreatine) }*' 



Carbonate of soda, 1 



Chloride of sodium, ! 10 to f/40 



Chloride of potassium, | 



Phosphate of lime, 1 ' 000 1 ' 000 



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 principle of the pancreatic juice are distinctive. 

 Although, like albumen, it is coagulated by heat, the strong mineral acids, and absolute 

 alcohol, it differs from albumen in the fact that its dried alcoholic precipitate can be re- 

 dissolved in water, giving to the solution all the physiological properties of the normal 

 pancreatic secretion. Bernard has also found that pancreatine is 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 pancreatine and other nitrogenized 

 principles, especially albumen, from the fact that the last-named substance has the prop- 

 erty of forming an emulsion with fats, though not so readily and completely as the pan- 

 creatic juice; and it is essential to decide whether the organic principle be a peculiar 

 and distinct substance, or albumen transuded pathologically, perhaps, from the blood. 

 There can be no doubt, in view of the marked chemical and physiological peculiarities of 

 pancreatine, that this is a distinct proximate principle, which is characteristic of the 

 pancreatic secretion and found in no other fluid. 



Kesearches have shown that pancreatine is the essential physiological constituent of 

 the pancreatic juice and the only one which gives this fluid its peculiar digestive proper- 

 ties. 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 principle alone, extracted 

 from the pancreatic juice and dissolved in water, is 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. 



