270 THE ANIMAL. XII. 



known as cKyme. The chyme then passes into the intestines. 

 The proteids are the principal constituents of the food affected 

 by the gastric juice, though the melting of the fat and the re- 

 moval of the cell walls from fatty tissue are important physical 

 changes. In the case of animals fed upon starchy foods, a 

 slight amount of hydrolysis, resulting in the formation of sugar 

 and also of lactic acid, is said to occur in the stomach. The 

 chief effect, however, may be said to be the action on the 

 proteids. 



The secretion of the glands of the intestines has a strong 

 alkaline reaction and thus tends to neutralise the acidity of the 

 chyme. It has also the property of inverting cane sugar and 

 maltose. The secretions of the pancreas and the liver are 

 next brought into contact with the chyme. 



Pancreatic juice is a viscid liquid of alkaline reaction con- 

 taining albumin, fat, soaps, alkaline carbonates, phosphates, 

 lime, magnesia, and iron. Its characteristic constituents, how- 

 ever, are three enzymes a diastatic one, a fat-splitting one, 

 and a proteolytic one. 



The composition of pancreatic juice appears to be very 

 variable ; the amount of total solids, for example, has been ob- 

 served to vary from 1-5 to 11 -5%. 



Hammarsten states that the solid matter in the pancreatic 

 juice of the horse varies from *9 to 1'8%, in that of the sheep 

 from 1-4 to 3-7%, and of the rabbit from 1-1 to 2-6%, and in 

 that of man it is about 2-4%. 



The amount of ash, chiefly common salt, appears to be 

 generally from -6 to -8%. 



The most important constituents are, of course, the enzymes. 



(1) The pancreatic diastase or amylopsin. This body is 



similar in many respects to ptyalin, but appears to be 

 distinct from it. It acts upon starch more energetically, 

 even attacking and dissolving unboiled starch. It yields 

 dextrin and maltose. 



(2) The fat-splitting enzyme, steapsin, or pialyn. This 



enzyme has the power of hydrolysing the fats, i.e., de- 

 composing them into glycerol and free fatty acids, which, 

 in the alkaline liquid, probably form soaps, and at the 

 same time of emulsifying them. 



