192 



Serum I 6 with strain H 303, 



— 135 I 29 and I 38 (I 35 and I 38 were cultivated from 



the same person at different times). 



— 191 — II 



— H34 — H 299 



— 134 — H 344 



— 136 — Ms 13, H 260, H 263, H 269, H 294, H 296, H 302, 



H 308, H 309, H 310, and H 311. 



The property of absorption was only observed in the strains 

 showing strong agglutination with the serum which was 

 absorbed. 



The spinal strains Me la, Me 2, Me 3 and Me 4 were 

 thoroughly investigated by agglutination and absorption tests 

 (using sera corresponding to the first three strains), which 

 gave the following results. 



In the ordinary agglutination test Me la, Me 3 and Me 4 were 

 about the same, bul Me 2 was rather different from the others 



In the absorption test Me 4 absorbed the agglutinin for Me la 

 and for Me 3, while Me la absorbed the agglutinin for Me 3, 

 but Me 3 could not absorb the agglutinin for Me la. No rela- 

 tionship was found between Me 2 and the other strains by the 

 absorption tests. i 



Me 5 was partially agglutinated in a later experiment by the 

 three sera but the reactions were not clearly defined. 



The meningeal strains therefore seem to be closely related 

 without however being identical. The numerous group agglu- 

 tinations between Me la and the strains of different origin 

 prove that the meningeal strains are not sharply separated 

 from other Pfeiffer's bacilli, but occupy a natural position in 

 the great Pfeiffer's bacillus group. 



The agglutinalory relationship between the meningeal and the 

 other strains was further confirmed by agglutination tests with the 

 14 sera used in the large series of experiments, except I 36 against 

 the strains Me la, Me 2, Me 3. All three strains showed group 

 agglutination in variable degrees with the majority of these sera. 



Concerning the constancy of the agglutination reactions 

 the following may be said. The homologous agglutination 

 reactions, as far as they have been investigated, have kept very 

 constant apart from small irregular variations, in spite of 



