248 MODERN BIOLOGIC THERAPEUSIS 



same species of bacteria that is, several 

 ''strains" of the microorganism are used the 

 cultures being obtained from many different 

 sources of infection in which that species of bac- 

 teria is found. 



The bacterial cultures are suspended in phy- 

 siologic salt solution and thoroughly shaken to 

 separate the microorganisms ; the bacterial sus- 

 pension is subjected to a careful count; the bac- 

 teria are killed by heating the suspension and 

 by the addition, after cooling, of 0.25 per cent 

 trikresol. The suspension is then diluted with 

 sterile physiologic salt solution containing 0.25 

 per cent trikesol until each cubic centimeter con- 

 tains the desired number of bacteria. 



AUTOGENOUS vs. STOCK VACCINES 



A great deal of discussion has arisen regard- 

 ing the question as to whether it is advisable to 

 use autogenous vaccines that is, vaccines that 

 are prepared from cultures of the bacteria ob- 

 tained from the patient; or whether it is better 

 to make use of stock vaccines prepared from 

 cultures of the microorganisms causing the in- 

 fection, but not derived from the particular in- 

 dividual to be treated. As long as we know so 

 little of what vaccines may accomplish, it is 



