74 INOCULATION OF CULTURE-MEDIA WITH BACTERIA. 



A culture-tube three-fourths full of the medium is heated 

 to the boiling-point and allowed to cool to a temperature in 

 the neighborhood of 40 C.; then a platinum needle charged 



FIG. 37. 



Incubator used in bacteriological work : a represents the incubator set up and 

 containing a cage of tubes and a Petri dish; 6, represents a vertical section of 

 the incubator and displays the water-chamber, inner chamber, walls, vents, ther- 

 mometer, valve, etc. 



with the material for inoculation is dipped down to the bot- 

 tom of the tube. With fluid media, immediately thereafter 

 a layer of paraffin oil is poured on the surface of the liquid 



