HEMOLYTIC STAPHYLOCOCCI 29 



absorb the homologous agglutinins after 4 hours' incubation at 37 C., 

 the tubes being shaken at half-hour intervals. After this period of 

 incubation the tubes were centrifugalized and the supernatant serum 

 dilution (1:50) was drawn off and agglutinations carried out as 

 described. 



Serum Al was absorbed with strain Al and X ; serum T9 with P3 

 and T2 ; serum LI with A5, P3 and T9, and agglutinations performed 

 against the antigens which agglutinated with the respective serum 

 before absorption. The results are presented in table 13. 



The absorption tests confirm the groups found by agglutination. 

 Group 1 remains as was found, but in group 2, H2, is placed in a 

 subgroup because although it agglutinates with the same serums as 

 A5, absorption by AS does not remove agglutinations for H2. In 

 group 3, P3 is placed in a subgroup. P3 removes agglutinins for all 

 members of group 3, but the other members of group 3 do not remove 

 agglutinins for P3. 



Revising our classification, then, we would have : 



Group 3 

 T2 

 T9 

 X 



Subgroup 

 P3 



DISCUSSION CF SEROLOGIC REACTIONS 



The use of complement fixation in determining types among the 

 staphylococci appears to be worthless. Although staphylococci do fix 

 complement, no grouping appeared possible, either quantitatively or 

 qualitatively. Nor is this surprising on the contrary, it is more or 

 less what was to be expected. Complement fixation has been dis- 

 appointing in its inability to differentiate types probably because the 

 immunity established although specific for the particular species is 

 general and not sufficiently specialized to detect individual types. 



Agglutination, however, has already been proved to be an efficacious 

 means of detecting types. Furthermore, agglutination is a fixed quality, 

 and one which is considered reliable. So that, when the statement is 



