VACCINE-THERAPY 19 



taken not to allow the medium to stick on the mouth or neck 

 of the test-tube. 



The tubes are usually charged with H to 2 inches of 

 medium. They should now be sterilized in a Koch sterilizer 

 for half an hour on three successive days, and laid on 

 their sides to cool to give a sloped surface, or upright for a 

 stab culture, as the case may be. 



