ANTISERA. 



39 



eluding opsonins, bacteriolysins, and to some extent 

 agglutinins and precipitins ( see Chapters IX, X, XI 

 and XX). 



The standardization of dosage of antibacterial sera 

 is therefore more difficult and uncertain than that of 



Fig. 2. — Illustrative of opsonic curve, showing immunity of rabbit inoculated with liv- 

 ing tubercle bacilli of low virulence. © = opsonic indices ; X = inoculations. 



antitoxic sera, but the potency of an antibacterial 

 serum can to some extent be gauged by determination 

 of the opsonic index from time to time during the im- 

 munization of the animal (Fig. 3) , and also by testing 

 the agglutinating power of the serum, though the lat- 

 ter method is of only slight value as an indication of 



