INOCULATING SPECIAL MEDIA 47 



however, to determine the acid and gas production in the test 

 tubes than to use the fermentation tubes, and it is cheaper. 

 It is convenient, therefore, to use these tubes with the sugar 

 media as follows : 



1. If to determine the power of the organism to produce 

 gas, use only the agar tubes. 



2. If to determine the power of the organism to ferment 

 sugars, producing acids, use only test tubes of bouillon. 



3. If to determine the quantity of gas produced and approxi- 

 mately its composition, use the fermentation tube. In this 

 exercise all three are called for. 



