IMMUNITY. 357 



adding human blood serum to bouillon and 

 with these brought about a condition of high 

 immunization or tolerance of poison employed 

 the serum of animals immunized in this fashion 

 to protect against streptococcus infections. 

 These streptococci are the germs of puerperal 

 fever and erysipelas, and are also especially 

 concerned in the septic conditions of diph- 

 theria. The streptococcus serum therefore 

 supplements, as it were, the diphtheria serum 

 in complicated cases and mixed infections. 

 These investigations are just beginning to be 

 taken up scientifically, and are in part still in 

 the advertisement stage ; we shall have to sub- 

 mit to many a serum before connection is again 

 made with scientific investigation. 



Phagocytes and Alexius Antitoxic and Bac- 

 tericidal Substances in the Blood. 



Up to this point we have considered only 

 the subject of " specific " immunizations and 

 the establishment of habituation to poisons. 

 These phenomena seem to present a funda- 

 mental contrast to those of natural resistance 

 or immunity. H. Buchner, especially, has 

 laid great stress upon this contrast, In na- 

 tural immunity there exists only the specific 

 ability of the body to cope with definite para- 

 sites and their poisons ; in " specific " irnmu- 



