BACTERIOLOGY. 163 



in the sink on the drain-board; wash them until the 

 color of the solution disappears. 



FLASKS AND PETRI DISHES. 



Wash them with soap and water ; then fill them with 

 the fluid and allow it to remain ten minutes. Proceed 

 as in the other case. 



COVER GLASSES AND SLIDES. 



Drop the cover glasses in the fluid one by one and 

 let remain ten minutes. Take them out and wash 

 them in alcohol; then place them in the sterilizer at a 

 temperature of 160 degrees C for one hour. If a drop 

 of bouillon is spread on a cover glass, the drop will 

 spread out evenly if the cover-glass is clean. 



PLUGGING TUBES. 



-This is a simple process, but much depends on the 

 way you do it. The plug should be neatly made and 

 firmly rolled just large enough to fit the test-tube or 

 flask. They are usually made of cotton-batting, which 

 should be sterilized before being used. The plug 

 must not be too large or too small. It is best to have 

 them just large enough to fit the tube or flask and no 

 larger. The whole must be sterilized. 



