1 50 BA CTERIOL OGY. 



necessary. Under these conditions we heat the food- 

 staffs for thirty minutes to such a temperature (70 C.) 

 as will kill the bacteria in the vegetative form, but 

 allow the spores to remain alive. Even this amount 

 of sterilization retards greatly the rapidity of putrefac- 

 tion and fermentation. 



