84 



ESSENTIALS OF BACTERIOLOGY 



Gases like Hydrogen to Replace the Oxygen. Several 

 arrangements for passing a stream of hydrogen through the 

 culture : 



Frankel puts in the test-tube a rubber cork containing two 

 glass tubes, one reaching to the bot- 

 tom and connected with a hydrogen 

 apparatus, the other very short, 

 both bent at right angles. When 

 the hydrogen has passed through 

 from ten to thirty minutes, the 

 short tube is annealed and then the 

 one in connection with the hy- 

 drogen bottle, and the gelatin 

 rolled out upon the walls of the 

 tube (Fig. 28). 



Use of Aerobic Bacteria to 

 Remove the Oxygen. Roux in- 

 oculates an agar tube through a 

 needle-thrust, after which semi- 

 solid gelatin is poured in on top. 

 When the gelatin has solidified, the 

 surface is inoculated with a small 

 quantity of Bacillus subtilis or 

 some other aerobic germ. The 

 subtilis does not allow the oxygen 

 to pass by, appropriating it to 

 itself. 



Buchner's Method. The test- 

 tube containing the culture is 

 placed within a larger tube, the 

 lower part of \vhich contains an 

 alkaline solution of pyrogallic acid. 

 The tube is then closed with a rub- 

 ber stopper (Fig. 29). 



Botkin's Method. Petri dishes, uncovered, are placed 

 on a rack under a large bell-jar, into which hydrogen gas is 

 conducted. Alkaline pyrogallic acid is placed in the upper 



Fig. 30. Wright's 

 method for the cultivation 

 of anaerobes. 



