101 



Absorption experiments were also made with the strains 

 showing marked group agglutination in rather more than 100 

 combinations of serum and culture. In cases of doubtful ab- 

 sorption the experiment was repeated often several times, partly 

 with renewed absorption, as mentioned on p. 183. 



• Further, about 40 of the oldest strains were tested as re- 

 gards absorption against Sj 5 Sj 21SH34' and S p a5 in such 

 a manner that 2 — 3 cultures at a time were mixed together 

 and tested against each serum. If absorption took place the 

 experiment was repeated with each culture.* 



With regard to their power of absorption the strains can 

 be divided into 3 groups: (1) The larger number did not absorb 

 so much of the agglutinin that its disappearance could be de- 

 monstrated with certainty; (2) Some of them 1 absorbed slowly, 

 so that with one absorption about half the agglutinin was 

 removed, and with repetitions of the process gradually the bulk 

 of it disappeared; (3) Some absorbed the agglutinin about as 

 easily as the homologous strain so that the major part of 

 it was removed by one treatment. 



As an instance of a slowly absorbing strain, 154 (experiment in 

 December 1919) may be cited. 



Q , , , }/200 V400 1 !sO0 Vl600 1 /3200 



a I6 T lb + + + 



S I6 (1 : 160), I 54 (circ. 10) + I 6: after 1st. absorption -f -f 



— 2nd. — +0000 



— 3nd. — 



It would lead too far to enter further into details of the 

 absorption experiments. The combinations of serum and cul- 

 ture only need be mentioned with which certain absorption 

 could be observed. (Strains which were thus proved to be 

 associated, will be referred to later as belonging to the same 



type). 



Weak absorption was observed in the following experiments: 



Serum 1 6 with strain I 54, 1 



Serum H 34 with strains I 20 and I 21, 



Serum I 36 with strain H 264, H 265, H 266, H 288 and H 289. 



Strong absorption was observed in: 



* The plate cultivations which resulted in the splitting of strains 

 II, I 22 etc. into (a) and (b) had not yet been made at this lime. 



