150 Immunity 



combining with the elements to be destroyed and so activat- 

 ing the complements. 



No satisfactory method of experimentally increasing the 

 complement has been devised. If, as Metschnikoff supposes, 

 the complement is microcytase derived from disintegrated 

 leukocytes, aseptic suppurations with active phagolysis 

 should result in marked increase of the complement. As a 

 matter of fact, this does take place, but the increase is so 

 slight that the serum is not practically valuable. 



Therapeutic serums whose practical application is based 

 upon their cytolytic activity must, of necessity, contain 

 both the essential factors involved in cytolysis, and should 

 contain them in such proportions that, regardless of other 

 elements in the blood, they can exercise their combining and 

 dissolving functions. 



We are unable experimentally to accomplish these pre- 

 requisites, therefore are not in the position to accurately 

 apply bacteriolytic serums in practice. 



