FORMATION OF DEFENSIVE FERMENTS 59 



Experiments were then made with gliadin and with 

 peptones obtained from gelatine, from edestin, and 

 from casein. Edestin and casein were also injected 

 by themselves. In all cases the result was the 

 same. When substances, that are out of harmony 

 with the plasma, are introduced into the plasma or 

 serum of a given animal, we always find developed a 

 special power of decomposing bodies belonging to 

 the protein series, especially protein itself and its 

 peptones. A specific activity of the injected sub- 

 strates could be traced only so far as that, after the 

 injection of proteins and peptones, ferments appeared 

 in the plasma which were able to chemically reduce 

 the derivatives of this group, but not, for instance, 

 fats or carbohydrates. Conversely, no splitting 

 of protein could be traced after injections of 

 fats, of carbohydrates, or of amino-acids. On the 

 other hand, after injection of a particular protein, or 

 of a particular peptone mixture derived from a definite 

 protein, not only were the injected substances 

 decomposed by the plasma, but the decomposition 

 extended to the whole group of proteins and their 

 nearest derivatives. 



That the process actually depends upon the pres- 

 ence of ferments can be proved in two ways. In the 

 first place the splitting of a particular peptone 

 solution, by the plasma of suitably prepared animals, 

 was compared with the action of extracted yeast 



