192 COLLOIDS IN BIOLOGY AND MEDICINE 



support of this view, E. PRIBRAM and E. STEIN injected through a 

 tube into the stomach of one rabbit an active solution of rennin, 

 and into the other, one inactivated by boiling. After four hours the 

 rabbits were killed and the amounts of pro-ferment contained in their 

 gastric mucous membranes were measured. The gastric mucous mem- 

 brane of the rabbit treated with active rennin contained much more 

 pro-enzyme than the other. From this, the authors deduced that the 

 colloidal gastric mucous membrane adsorbed the rennin and changed 

 it into pro-enzyme. S. G. HEDIN* also views zymogen as the com- 

 bination of an enzyme (rennet) with an inhibiting substance. In the 

 condition studied especially by him, rennet is freed by hydrochloric 

 acid, the inhibiting substance is let free by ammonia, with the 

 destruction of the rennet. 



