VACCINES IN TREATMENT OF DISEASE 241 



more important principle has resulted from 

 studies in immunology than that the process of 

 immunity in each infection must be studied by 

 itself; hence, a definite method of procedure 

 must be adopted in every individual case. 



Dosage The importance of small doses of 

 vaccine, such as would give the maximum op- 

 sonic response, and the necessity of giving suc- 

 cessive doses at sufficient intervals of time to al- 

 low the development of the maximum reaction 

 from the previous inoculation, were emphasized 

 repeatedly by Wright. The principles of the 

 therapeutic use of bacterial inoculations were 

 developed from careful studies of subacute and 

 chronic localized infections, in which the focus 

 of infection was more or less walled off from 

 the rest of the body and in which phagocytosis 

 occupied a prominent place in the pathologic 

 changes in the focus of infection. 



While the dose should not be too large, neither 

 should it be too small. There is a proper dose 

 for each patient, and this may be determined 

 by starting with a small dose and gradually in- 

 creasing it until some reaction is secured. An 

 efficient dose may produce some reaction, and 

 increased doses are contraindicated so long as 



