44 LABORATORY BACTERIOLOGY 
employed in studying and differentiating species of bacteria 
have been arranged arbitrarily in groups. Large test tubes 
containing agar and gelatin for making plate cultures are not 
included in these groups. 
Group A. Media commonly used. 
LA tube of bouillon. 
A tube of sugar-free bouillon. 
A tube of agar. 
| A tube of gelatin. 
A tube of milk. 
~ A tube of litmus milk. 
' A tube of potato. . 
Group B. Media favorable to determine the ‘power of bac- 
teria to ferment the sugars with the formation of acids. 
1 A tube of bouillon containing 1% grape sugar (dextrose, 
glucose). 
~ A tube of bouillon containing 1% milk sugar (lactose). 
~ A tube of bouillon containing 1% cane sugar (saccharose). 
Group C. Media favorable for determining the production 
of gas. 
A tube of agar containing 1 % grape sugar. 
A tube of agar containing 1% milk sugar. ® 
A tube of agar containing 1 % cane sugar. 
Group D. Media and tubes favorable for approximate gas 
analysis and the determining of the aérobic or anaérobic 
tendencies. 
Fermentation tube containing 1 % grape-sugar bouillon. 
Fermentation tube containing 1 % milk-sugar bouillon. 
Fermentation tube containing 1 % cane-sugar bouillon. 
The fermentation tubes containing bouillon with sugars may be 
substituted for the media containing sugars in Groups B and C if 
desired. , 
