Laboratory Outline for General Bacteriology 



CAUTIONS AND DIRECTIONS FOR IDENTIFICATION 

 OF UNKNOWN CULTURES 



J 



1. Do keep cultures pure so correct results may be obtained. 



Agar Slants 



2. Do touch only the tops of cotton plugs when removing them 

 from and replacing them in tubes. While out hold between 

 fingers with lower parts away from hand so they will not touch 

 anything. 



3. Do burn off cotton adhering to mouth of tube instead of pulling 

 it off with the fingers, rods, etc. 



4. Do sterilize the needle or loop by heating entire length of wire 

 to redness and pass lower part of holder through flame three 

 or four times before making a transfer. 



5. Do allow needle to cool before using. 



6. Do hold needle so nothing touches it while cooling. 



7. Do avoid opening tubes in currents of air. Bacteria may be 

 blown in. 



8. Do hold tube nearly horizontal while making transfers so 

 bacteria cannot fall in. 



9. Do push plugs in until they are firm. 



10. Do use care to keep all cultures pure even when you think it is 

 the last time they will be used. 



11. Do keep all cultures until advised to discard them. 



12. Do make records complete. 



13. Do record all negative as well as positive results. 



14. Do remember that "chromogenesis" refers to the color of the 

 bacterial growth itself, not to the color of the medium on 

 which the bacteria are growing. 



15. Do touch surface of agar slants so lightly that needle or loop 

 never breaks into the medium. Bacteria are usually only on 



the Surface. (Continued on Page 24) 



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