142 PHYSIOLOGICAL CHEMISTRY. 



of converting trypsinogen into trypsin. This process is known as 

 the "activation" of trypsinogen and through it a juice which is 

 incapable of digesting protein may be made active. Enterokinase 

 is not always present in the intestinal juice since it is secreted only 

 after the pancreatic juice reaches the intestine. It resembles the 

 enzymes in that its activity is destroyed by heat, but differs mate- 

 rially from this class of bodies in that a certain quantity is capable 

 of activating only a definite quantity of trypsinogen. It is how- 

 ever generally classified as an enzyme. Enterokinase has been de- 

 tected in the higher animals, and a kinase possessing similar proper- 

 ties has been shown to be present in bacteria, fungi, impure fibrin, 

 lymph glands and snake- venom. The activation of trypsinogen 

 into trypsin may be brought about in the gland as well as in the 

 intestine of the living organism (Mendel and Rettger). The 

 manner of the activation in the gland and the nature of the body 

 causing it are unknown at present. 



Delezenne claims that trypsinogen may be activated by soluble 

 calcium salts. He reports experiments which indicate that pro- 

 teolytically inactive pancreatic juice, obtained directly from the duct, 

 when treated with salts of this character assumes the property of 

 digesting protein material. This process by which the trypsinogen 

 is activated through the instrumentality of calcium salts is very 

 rapid and is designated by Delezenne as an " explosion." The 

 recent suggestion of Mays that there may possibly be several pre- 

 cursors of trypsin one of which is activated by enterokinase and 

 the others by other agents, is of interest in this connection. 



Pancreatic amylase (amylopsin), the second of the pancreatic en- 

 zymes, is an amylolytic enzyme which possesses somewhat greater 

 digestive power than the salivary amylase (ptyalin) of the saliva. 

 As its name implies, its activity is confined to the starches, and 

 the products of its amylolytic action are dextrins and sugars. The 

 sugars are principally iso-maltose and maltose and these by the 

 further action of an inverting enzyme are partly transformed info- 

 dextrose. 



It is possible that the saliva as a digestive fluid is not absolutely 

 essential. The salivary amylase (ptyalin) is destroyed by the hy- 

 drochloric acid of the gastric juice and is therefore inactive when 

 the chyme reaches the intestine. Should undigested starch be pres- 

 ent at this point however, it would be quickly transformed by the 

 active pancreatic amylase. This enzyme is not present in the 

 pancreatic juice of infants during the first few weeks of life, thus- 



