ACTION OF THE ENZYMES. 159 



original 3.2 gms. of arginin that were added to such an 

 extract, were split, 2.0 gms. of ornithin and I.I gms. of urea 

 being recovered from the reaction mixture. In another 

 experiment 3.3 gms. of arginin of the original 3.6 gms. 

 added were split, 2.7 gms. ornithin and 1.2 gms. urea being 

 recovered. 



These experiments furnish an interesting example of the 

 apparent ease with which chemical changes are brought 

 about in a living organism, which in vitro cannot often be 

 accomplished without resort to what may be termed coarse 

 chemical procedures. The ease with which arginase splits 

 arginin into ornithin and urea stands in sharp contrast to 

 the difficulty with which this same chemical change is brought 

 about under the influence of boiling mineral acids. 



The experiments of KOSSEL and DAKIN give us an insight 

 nto the means by which urea is produced in the liver and 

 various other organs of the body. Whether the urea which 

 was found by CLAUDE BERNARD and others in the secretions 

 )f the intestine is dependent upon the presence of this en- 

 zyme in the wall of the gut, or whether we have in addition 



true excretion of this substance by the intestinal canal, 

 cannot be settled until further experiments have been made. 1 



See Chapter XVIII, Part 1. 



