4 LABORATORY GUIDE IN BACTERIOLOGY 



etc., should be put into crocks and not on the floor or 

 into the sink. 



7. Discarded cultures should be killed in the auto- 

 clave (5 minutes at 120° C.) before being emptied into 

 the crocks. 



8. See that the air inlets of Bunsen burners are open 

 before lighting, and relight if the flame strikes back. 



9. Always return stockbottles to the proper places 

 on the shelves. 



10. At the close of the day's work the desks should 

 be washed off with corrosive sublimate, and the hands 

 cleaned by thorough washing. 



11. Before leaving the laboratory, see that the gas 

 is shut off under" all apparatus, that water faucets are 

 closed, and that all glassware, etc., is replaced in the 

 lockers. Culture tubes containing media or cultures 

 should be replaced in their proper places, in order to 

 avoid settling of dust or other foreign material on the 

 stoppers. Dust and air draughts are frequently the 

 cause of contaminations, and in order to avoid these 

 the utmost cleanliness should be observed. A bacteri- 

 ological laboratory should present an orderly appear- 

 ance at all times. 



SECTION 2 

 GENERAL DIRECTIONS 



The following directions should be followed in all 

 the work outKned in this guide: 



I. After obtaining the key to a locker, the student 

 should examine the outfit, check all apparatus, and see 

 that everything is in good condition. 



