88 INTRODUCTION. 



infant, converted into albuminose, which it resembles very 

 closely, and absorbed by the blood, where it is converted into 

 fibrin and albumen, and contributes to the nutrition of the 

 system. At this period it constitutes almost the only nitro- 

 genized element of food. It is the only proximate principle 

 of this class, with the exception of a little mucosine and the 

 coloring matter of the urine and bile, which is discharged 

 from the body in health. 



Panereatine. 



This is the organic principle peculiar to the pancreatic 

 juice. Bernard was the first to describe its properties, both 

 chemical and physiological. 1 Before the appearance of his 

 admirable monogragh on the pancreas it was confounded with 

 albumen; but we shall see that it possesses properties by 

 which it may be distinguished as readily as casein e. 



Panereatine exists in the pancreatic juice in large quan- 

 tity. It is naturally fluid, but very viscid. It is coagulated 

 by heat, the strong acids, and alcohol, but is unaffected by 

 the feeble vegetable acids. It is distinguished from albumen 

 by the fact that it is completely coagulated by an excess of 

 sulphate of magnesia. Its distinctive physiological character 

 is its powerful digestive action upon certain elements of food, 

 and its property of forming an instantaneous, complete, and 

 very fine emulsion with liquid fats. 



Panereatine has its origin from the albumen of the blood 

 by a catalytic change which takes place in the pancreas. It 

 gives to the pancreatic juice its digestive properties. 



Pepsin. 



Pepsin is the organic principle of the gastric juice. It 

 is hardly to be distinguished from albumen, except by its phys- 

 iological action in digestion. The principle which has been 

 extracted by various processes from the mucous membrane 



1 BERNARD, Memoire sur le Pancreas, Paris 1858. 



