334 BIOLOGY OF PNEUMOCOCCUS 



not received a previous injection of the dyed cocci. Sergent's appli- 

 cation of coal-tar dyes to pneumococci for the purpose of prepar- 

 ing immunizing antigens appears to be a lone observation of its 

 kind. 



Nicolle and Adil-Bey (1907) 1007 obtained immunity in rabbits 

 by the injection of cultures treated with sodium choleate, while 

 Meyer (1927) 897 and later Meyer and Sukneff (1928) 898 reported 

 that Type I pneumococci dissolved in sodium taurocholate would 

 immunize both rabbits and mice. The serum of the rabbits so 

 treated contained a moderate amount of protective substance but, 

 as might be expected, the serum as a rule gave some cross-protec- 

 tion against Type II strains. While pneumococci treated with bile- 

 salts may induce immunity in mice and rabbits and presumably in 

 other animals, the immunity is of a low order and is lacking in 

 type-specificity. As late as 1933, Ziegler 1573 advocated as an immu- 

 nizing agent "Pneumocholin," a substance of unknown chemical 

 composition produced by the lysis of pneumococci in sodium 

 taurocholate solution. The substance was stable under refrigera- 

 tion and, when injected into rabbits, induced after three or four 

 days an effective immunity to Type I infection. 



Larson and Nelson 791 recommended the use of sodium ricinoleate 

 in the preparation of pneumococcal vaccines both for prophylactic 

 use in man and for the preparation of therapeutic serum. A viru- 

 lent culture of Pneumococcus treated with ricinoleate soap in a 

 final concentration of 0.1 per cent immediately lost its patho- 

 genicity and, according to the authors, when injected intraperi- 

 toneally into rabbits, stimulated the production of large amounts 

 of agglutinins within twenty-four hours. The animals resisted 

 many multiples of the infective dose of pneumococci, and their se- 

 rum protected normal rabbits against both intravenous and intra- 

 peritoneal infection. The serum of rabbits and sheep immunized 

 with the sodium ricinoleate antigens was claimed to possess dis- 

 tinct curative properties for rabbits infected with Pneumococcus. 

 The administration of the immune serum to patients suffering 



