58 FORMATION OF DEFENSIVE FERMENTS 



into the organism, so as artificially to avoid the dis- 

 integrating action of the ferments of the intestines. 

 These substances are injected either subcutaneously, 

 or into the abdominal cavity, or else intravenously. 

 After a certain lapse of time blood is extracted, and 

 its serum, or plasma, is treated exactly in the same 

 way as we have described above. 



The first experiments were made with dogs and 

 rabbits. White of egg, or horse blood-serum, was 

 introduced parenterally into these animals, that is to 

 say, avoiding the intestinal canal ; tests were then 

 made to see whether the plasma of the animals 

 under experiment either decomposed certain poly- 

 peptides, or whether it decomposed them quicker 

 than the plasma of the same animal did before the 

 injection of the disharmonious substance. The very 

 first experiments gave a positive result. It was found 

 that the contents of the blood increased in peptolytic 

 ferments. In a further experiment the substance used 

 for the injections was silk-peptone. It was found 

 that the serum of normal rabbits did not reduce 

 this peptone at all, the angle of rotation of the mixture 

 of plasma + peptone remaining constant. But if 

 silk-peptone be injected into an animal, and 

 the serum of the latter be then brought into contact 

 with this peptone, then, if we take a rapid reading 

 of the rotation in a polariscope, we find that the 

 initial rotation alters in the course of time. 



