

CHAPTER VI. 

 STERILIZATION AND DISINFECTION. 



BEFORE considering the cultivation of bacteria and the 

 preparation of media for that purpose, it is necessary to 

 have a thorough knowledge of the principles of sterilization 

 and disinfection in order intelligently to comprehend the 

 methods employed for the destruction of those bacteria whose 

 accidental presence might ruin our experiments. 



The dust of the atmosphere, as has already been shown, 

 is almost invariable in its micro-organismal contamination, 

 so that spores of micro-organisms constantly settle from it 

 upon our glassware, pots, kettles, funnels, etc., and would 

 certainly ruin every medium with which we experiment 

 did we not take appropriate measures for their destruction. 



To get rid of these undesirable " weeds " we make use of 

 our knowledge of the conditions destructive to bacterial life 

 and subject the articles contaminated by them to the action 

 of heat beyond their known enduring power, or to the action 

 of chemic agents known to destroy them, or remove them 

 from fluids into which they have entered by passage through 

 unglazed porcelain. By all of these methods the articles 

 are made sterile. Anything is sterile when it contains no 

 germs of life. 



Sterilization is the act of making sterile by destroying all 

 the germs of life. It makes no difference whether these 

 germs are infectious or non-infectious. Disinfection refers 

 to the destruction of the infective powers. It, therefore, 

 signifies the destruction of the infectious agents, taking no 

 account of those that are non-infectious. Sterilization is 

 of the utmost importance to the bacteriologist, disinfection 

 to the sanitarian. A germicide is any substance that will 

 kill germs. It is used for disinfection and for sterilization. 

 An antiseptic is a substance that will inhibit the growth of 

 the germs. Germicides and antiseptics are of paramount 

 importance to the sanitarian, but of limited importance to 

 the bacteriologist. 



The following list of germicides is chiefly extracted from 

 the work of Sternberg and Micquel : 



173 



