158 PHYSIOLOGY OF ALIMENTATION. 



ferent investigators regarding the presence or absence of 

 lactase in different organs and secretions of the alimentary 

 tract have been harmonized by the careful experiments of 

 WEINLAND. There seems to be no question but that lactase 

 is present in the secretions and mucous membrane of the small 

 intestine of all suckling animals and in certain adult animals, 

 provided they are fed milk-sugar or a food containing it. 

 The same holds true of the pancreas. Sucklings secrete 

 lactase in their pancreatic juice, and the gland contains 

 the enzyme. Adult animals come to have lactase present in 

 their pancreas if they are fed milk-sugar. 1 



14. Arginase. Under this heading KOSSEL and DAKiN 2 

 have described a ferment which has the interesting property 

 of acting upon arginin and splitting this into the chemically 

 much simpler ornithin and urea. The ferment is widely 

 distributed throughout the body, though it is present in 

 different amounts in the various organs. The liver probably 

 contains the largest amount, while next in order come the 

 kidneys, spleen, and intestinal mucous membrane. 



Arginase can be readily obtained by extracting any of the 

 organs named with water and dilute acetic acid, but, as with 

 other ferments, only a small portion of the ferment actually 

 present within the tissues can be gotten out. Absolutely 

 pure arginase has not as yet been prepared, but advantage 

 can be taken of the fact that it is readily precipitated by 

 ammonium sulphate, and alcohol and ether to free it from 

 many of the impurities which accompany the ordinary acetic- 

 acid extract. 



Some idea of the readiness with which arginase acts upon 

 arginin can be obtained from the following experiments, in 

 which are indicated the amounts of this substance which 

 may be split in ten minutes by an extract made from 25 

 gms. of liver substance. In one experiment 2.7 gms. of the 



1 See Chapter XII.. Part 7. 



2 KOSSEL and DAKIN: Zeitschrift fur physiol. Chemie, 1904, XLI, p. 

 341, and XLII, p. 183. 



