10 LABORATORY GUIDE IN BACTERIOLOGY 



at a temperature of 150° C. for about 30 minutes, or 

 until the plugs are -slightly browned. The tubes are 

 not necessarily sterile, but the plugs have become set 

 so as to fit the mouth of the tube, and maybe removed 

 and replaced readily. 



SECTION 4 



METHODS OF STERILIZATION 



Sterilization is the process of removing all living 

 organisms. This may be accomplished by heat, by 



Fig. 3 

 Berkefeld Filter 

 a. Berkefeld filter d. Intercepting flask 



6. Filtered liquid e. Connection with aspiratpr 



i,. Side tube witb cotton filter /. Ruljbw hQse 



