ANTIBODIES TO PNEUMOCOCCUS 391 



lacking in this stimulating property was also lacking in precipi- 

 tating, agglutinating, and complement-fixing action and displayed 

 no protective power. Boehncke and Mouriz-Riesgo (1915), 134 who 

 had previously corroborated the conclusion of Neufeld and Rim- 

 pau that the bacteriotropic action of antipneumococcic serum in 

 vitro also participates in the action of the serum in vivo, were not 

 convinced that tropins were the only factor in inducing phagocy- 

 tosis. The authors had been able to rule out any participation of 

 bactericidal and complement-fixing antibodies and, while they con- 

 cluded that phagocytosis was the most important factor, the au- 

 thors still inclined to the view that antitoxins might play an 

 important part in resistance to pneumococcal infection. In 1919, 

 Barber, 77 employing the single-cell technique, sought an explana- 

 tion of the ready growth of pneumococci in immune serum. Failing 

 to find any specific bactericidal substance in immune serum, Bar- 

 ber noticed that when specific serum was added to pneumococci 

 previous to mixing with leucocytes active phagocytosis took place, 

 and the same phenomenon occurred when the organisms were in- 

 jected into the peritoneal cavity of mice passively immunized with 

 immune serum. The author offered no explanation for the reac- 

 tion. 



SENSITIZATION OF PNEUMOCOCCI 



Burgers, 188 and Burgers and Meisner (1911), 189 following the 

 lead furnished by the work of Neufeld and Rimpau, found that 

 while normal serum was inactive in rendering virulent pneumococci 

 phagocytable, immune serum was highly active in this respect. Al- 

 though the serum used in the experiments was evidently low in po- 

 tency, the pneumococci when incubated with the serum were 

 readily taken up by normal leucocytes. Burgers and his colleague 

 believed that fresh complement was necessary for phagocytosis, 

 since they considered that the reaction was one depending upon 

 antigen, amboceptor, and complement. Strouse (1911 ) 1346 also 

 used the method of sensitizing pneumococci in studying the pres- 



