40 



APPLIED IMMUNOLOGY 



therapeutic strength. The dosage of antibacterial sera 

 is chiefly determined by the therapeutic effects ob- 

 tained. In general, antibacterial sera are not of so 

 much value as antitoxic sera, though in the case of a 



Fig. 3. — Illustrative of inoculations and curve of opsonic indices demonstrating immu- 

 nity of ram. © = opsonic indices; X = inoculations of Staphylococcus aureus. 



few organisms good results have been obtained. Active 

 immunization offers a greater field of usefulness than 

 passive immunization in infections of this type. 

 Indications for the Therapeutic Use of Antisera 

 In the case of infections with bacteria which act 

 through extracellular toxins, antitoxic sera have a 



