58 LABORATORY BACTERIOLOGY 



tube of sugar-free bouillon, and one containing i% glucose 

 bouillon with B. colt communis from a culture furnished. 



89. Liborius' Method. — Liquefy 2 tubes of agar and care- 

 fully pour them together. After this, boil the medium for at 

 least 5 minutes to expel the air, cool it down to a temperature 

 of 40° C. and then inoculate it from the culture of anaerobic 



bacillus (^B. ) furnished, after which cool the medium rapidly 



by standing it in cold water until it is set. In inoculating the 

 tube insert the loop nearly to the bottom and stir very gently. 

 In making the inoculations care must be taken not to introduce 

 air by shaking the liquid medium. Place the culture in the 

 incubator. 



90. The fermentation Tubes for Anaerobic Bacteria. — If 

 these tubes of bouillon have been properly sterilized, the closed 

 branch is practically free from atmosphere. The obligatory 

 anaerobe will grow in the closed branch only, while tlie faculta- 

 tive anaerobe will grow in both the. open and closed parts. If the 

 organism is a gas producer, the gas will force the cloudy liquid 

 from the closed bulb into the open one, clouding the otherwise 

 clear liquid. To avoid the possibility of error in interpreting 

 these growths, it is well to inoculate a tube containing sugar- 

 free bouillon, in which case the liquid in the open bulb should 

 remain clear, as gas will not be formed. 



These tubes are of equal value in testing obligatory and 

 facultative anaerobic organisms. 



