58 



ESSENTIALS OF BACTERIOLOGY. 



in the flame a second to singe the cotton plug to free it from dust, 

 and the plug removed, the edges of the tube again flamed, the bell- 

 glass lifted, and the inoculated gelatine carefully poured on the 

 plate, leaving about one-third inch margin from the borders ; the 



FIG. 31. 



Nivellier leveling and cooling apparatus. 



lips of the tube being sterile can be used to spread the media 

 evenly. If the plate is at all cool, the fluid will solidify as it is 

 being spread. The glass cover is replaced until the gelatine or 

 agar is quite solid to prevent contamination. 



FIG. 32. 



Moist chamber with plates on benches. 



When the gelatine is congealed, the plate is placed upon a 

 little glass bench or stand in the moist chamber. 



The Moist Chamber Prepared Out of Two Glass Dishes, as for 

 the Potato- Cultures. - The glass benches are so arranged that 

 one stands upon the other. In order to avoid confusion, a slip 

 of paper with a number written on it is placed on the bench be- 

 neath each plate. As the original or first plate would have the 

 colonies developed in greatest profusion, it is placed the first 



