CURATIVE VACCINATION. 379 



would eliminate the danger period mentioned 

 above, and before the serum disappears entirely 

 active immunity develops. 



Wright, following his observations on the varia- 

 tions in opsonic power of the serum in different 

 infections, concluded that in certain localized 

 chronic infections such as chronic suppurative 

 processes, the body as a whole did not respond to 

 the infection with the production of antibodies. 

 The injection of dead homologous organisms was 

 therefore resorted to in order, in the words . of 

 Wright: "To exploit in the interests of the in- 

 fected tissues, the unexercized immunizing capac- 

 ities of the uninfected tissues." 



The dosage of the injected vaccine was de- 

 termined according to the purpose of using the 

 minimum quantity which would result in the 

 maximum response of the uninfected tissues with 

 the least development of the so-called negative 

 phase. In order to regulate the frequency and 

 size of the therapeutic inoculations, Wright made 

 use of opsonic index estimations. 



Vaccines are prepared as follows: 



The desired organism is grown on a suitable 

 solid medium as an agar slant or blood serum 

 slant for the minimum time required for a good 

 growth, usually twenty-four hours. 



Salt solution is then added to the slant, a few 

 cubic centimeters are usually sufficient for an 

 ordinary growth (the quantity need not be exact), 

 and the culture scraped off into the salt solution 

 with a sterile glass rod or platinum loop. The 

 number of bacteria per cubic centimeter is then 

 estimated by mixing equal volumes of defibrinated 



