STERILIZATION 



11 



peratures, may be more quickly sterilized by heating in 

 steam under pressure. 



Exposure to steam at a temperature of 115 C. for twenty 

 minutes is in most cases sufficient to insure sterilization, 



FIG. 4. Autoclav, Horizontal, 

 for Steam or Gas. 



FIG. 5. Autoclav, Vertical, 

 for Gas Only. 



but some media, potato for instance, require a temperature 

 of 120 C. for ten to fifteen minutes. It is now realized 

 that media subjected to this high temperature undergo 

 hydrolytic changes which render them unsuitable for the 

 cultivation of more delicate microorganisms. Sterilization 



