76 PHYSIOLOGY OF ALIMENTATION. 



tion of starches. The ferment splits starches into malt- 

 ose and dextrin. Its presence in human intestinal juice 

 has been proved by NAGANO, HAMBURGER and HEKMA. 



Maltase. The occurrence of this enzyme in the small 

 intestine is still questioned. Evidence is slowly accumu- 

 lating, however, to show that it is to the presence of this 

 enzyme in the intestinal juice and the intestinal mucosa 

 that we owe the splitting of the maltose formed from starch 

 into the dextrose found in the intestine after the ingestion 

 of starch or malt-sugar. The presence of a maltose-splitting 

 ferment in human intestinal juice is indicated by the re- 

 searches of NAGANO, HAMBURGER and HEKMA. 



Sucrase (invertase, invertin) is one of the most important 

 enzymes found in the secretion of the small intestine. Cane- 

 sugar, which serves as such a common article of diet, would 

 without the presence of this enzyme be scarcely absorbed by 

 the intestine. The sucrase splits the cane-sugar into the 

 readily absorbable dextrose and laevulose. 



Lactase is found in the intestinal tract of infants and those 

 adults who consume milk-sugar either as a separate article 

 of diet or as one of the constituents of milk. Lactase acts 

 upon milk-sugar (lactose) and splits this into dextrose and 

 galactose. 



Arginase is a ferment which has recently been discovered 

 by KOSSEL and DAKIN. It has the interesting property of 

 splitting arginin into the two chemically much simpler sub- 

 stances ornithin and urea. It is a ferment which occurs not 

 only in the mucous membrane of the intestine, but also in a 

 number of the parenchymatous organs. 



Antiproteinase (antipepsin and antitrypsin). This sub- 

 stance is found in the mucosa of the intestine, but not in the 

 secretions of the intestine. Like the antiproteinase of the 

 stomach, it has the power of preventing the proteinases from 

 acting upon proteins and splitting them into their well-known 

 decomposition-products. 



Enterokinase. The ferment character of this substance 



