272 



SPECIFICITY OF OPSONINS 



remove it from a sample of serum, whereas a large number of 

 staphylococci are required. In this case opsonins will have a 

 sort of modified specificity comparable with that of the agglutinins 

 for the coli group, and this appears to harmonize Bulloch's results 

 with those of later observers. 



An example of this selective absorption of opsonins may be 

 given, chiefly to illustrate the methods employed in this class 



1-5 

 14 

 1-3 

 1-2 



II 

 I 



9 

 8 

 1 

 6 

 5 

 4 

 3 

 2 



gj 



FIG. 64. BEHAVIOUR OF OPSONIC INDEX TO STAPHYLOCOCCI AND TUBERCLE 

 BACILLI DURING NATURAL RECOVERY FROM AN ATTACK OF FURUNCU- 

 LOSIS. (Original.) 



of experiment. A specimen of normal serum was mixed with an 

 equal amount of very thick emulsion of staphylococci, kept at 

 37 C. for one hour, and then centrifugalized until all the cocci were 

 removed, leaving the fluid (a). A second amount of serum was 

 treated similarly, but the staphylococci emulsion was diluted 

 100 times (b). It was hoped that the staphylococcic opsonin 

 would be completely removed from the first, and only partially 

 removed from the second specimen. This was tested as follows : 



