488 DIGESTION IN THE INTESTINES. [CH. xxxn. 



(b) A small amount of proteid matter, coagulable by heat. 



(c) Traces of leucine, tyrosine, xanthine, and soaps. 

 The inorganic substances in pancreatic juice are 



Sodium chloride, which is the most abundant, and smaller 

 quantities of potassium chloride, and phosphates of sodium, 

 calcium, and magnesium. The alkalinity of the juice is due to 

 phosphates and carbonates, especially of sodium. 



The action of pancreatic juice, which is the most powerful and 

 important of all the digestive juices, may be described under the 

 headings of its four ferments. 



i. Action of Trypsin. Trypsin acts like pepsin, but" with 

 certain differences, which are as follows : 



(a) It acts in an alkaline, pepsin in an acid medium. 



(b) It acts more rapidly than pepsin ; deutero-proteoses 

 can be detected as intermediate products in the formation of 

 peptone ; the primary proteoses have not been detected. 



(c) An albuminate of the nature of alkali-albumin is formed 

 in place of the acid-albumin of gastric digestion. 



(d) It acts more powerfully on certain albuminoids (such as 

 elastin) which are difficult of digestion in gastric juice. It does 

 not, however, digest collagen. 



(e) Acting on solid proteids like fibrin, it eats them away 

 from the surface to the interior ; there is no preliminary swelling 

 as in gastric digestion. 



(/) Trypsin acts further than pepsin, on prolonged action 

 partly decomposing some of the peptone which has left the 

 stomach into simpler products, of which the most important are 

 leucine, tyrosine, arginine (see p. 402), aspartic acid, and ammonia. 



The peptones are diffusible because their molecules are smaller 

 than those of proteid. Peptone by the prolonged activity of 

 pancreatic juice is split into substances of still smaller mole- 

 cular weight. Antipeptone was so called because it resists this 

 action. It is, however, not a true peptone at all, but a substance 

 of extremely low molecular weight. Siegfried states it is a single 

 substance which he calls carnic acid (C 10 H 16 N 3 5 ), because he first 

 separated it from muscle. Kutscher finds, however, that it is a 

 mixture of several comparatively simple materials, histidine, 

 arginine, aspartic acid, etc. 



2. Action of Amylopsin. The conversion of starch into 

 maltose is the most powerful and rapid of all the actions of the 

 pancreatic juice. It is much more powerful than saliva, and will 

 act even on unboiled starch. The absence of this ferment in the 

 pancreatic juice of infants is an indication that milk, and not 

 starch, is their natural diet. 



