60 FORMATION OF DEFENSIVE FERMENTS 



juice on the same peptone. It was possible to 

 show that the decomposition in both cases was 

 very similar, i.e., that the initial rotation varied in 

 the same direction and to the same extent, whether 

 the plasma of specially treated animals was used, or 

 the active extract of yeast. 



The following experiment proved, with excep- 

 tional clearness, that the plasma of an animal, when 

 specially treated, actually reduces proteins. The 

 plasma was mixed with gelatine or with white of egg, 

 and the mixture was placed in a dialysation tube. 

 Very shortly the presence of peptones could be 

 demonstrated in the outer fluid distilled water being 

 chosen for this purpose by means of the biuret re- 

 action. But when plasma of normal animals was 

 mixed with albuminous bodies and placed in a 

 dialysation tube, no substances giving the biuret 

 reactions could be traced in the outer fluid, even after 

 standing for many days. Finally, it has been proved 

 quite recently that, by mixing the plasma or serum 

 of specially treated animals with albumen, the nitro- 

 genous contents of the outer fluid increase to a con- 

 siderably greater extent than when the plasma of 

 normal animals and albumen are mixed together. In 



o 



the last case the increase of nitrogen in the outer fluid 

 is no greater than when the same quantity of plasma 

 is brought into the dialysation tube by itself, i.e., 

 without addition of albumen. It must be understood 



