HISTORY OF PNEUMOCOCCUS: 1890-1900 23 



attempt to isolate this new curative substance, the Klemperers pro- 

 gressed far enough to be able to say that it also was a protein. 

 They believed that they had found an antitoxin for Pneumococcus, 

 but that mistake is of no importance in view of the value of their 

 major contribution. 



The work of the Klemperers gave new impetus to investigation. 

 Here was an alluring and promising field ; there loomed the possi- 

 bility of a biological cure for pneumonia. Emmerich and Fowit- 

 zky, 857 still using the subcutaneous route for the injection of 

 attenuated pneumococci, obtained only partial immunity in rabbits. 

 However, when they injected diluted, fully virulent cultures intra- 

 venously, the resistance appeared to be complete. Instead of using 

 the serum of these animals for protective or curative experiments, 

 they used the filtered juices expressed from the tissues. The fluids 

 so obtained were claimed to possess idealer Heilkraft but, although 

 Emmerich and Fowitzky considered their use justifiable for human 

 therapy, they employed the immune tissue extracts only in animal 

 tests. Bonome (1891) 137 tried sterile filtrates of bouillon cultures 

 injected every other day subcutaneously, intravenously, and intra- 

 peritoneally into rabbits and found that immunity appeared as 

 early as two or three days after the final injection. The toxicity of 

 the filtrates was directly related to the virulence of the strain, some 

 animals showing local reactions, others none. He employed, with 

 like effect, blood and spleen from mice killed by a culture insuffi- 

 ciently virulent to kill rabbits. The defibrinated blood of the 

 treated rabbits injected into the peritoneum of other rabbits pro- 

 tected them against lethal doses of the toxic filtrate, but only when 

 the blood was administered just prior to the injection of the fil- 

 trate or culture. 



Kruse and Pansini 763 likewise produced immunity with daily in- 

 jections of sterile filtrates of broth cultures. They attributed the 

 protective properties of the blood of the immune rabbits to bac- 

 tericidins, and although they observed phagocytosis, this was held 

 to be a secondary factor. In their paper, apart from the immuno- 



