METHODS USED IN CULTIVATION OF BACTERIA 



151 



chamber, are kinked. The entire apparatus may then be incubated. 

 Growth of anaerobic bacteria takes place within the air-tight chamber 

 formed by the short glass tubing within the test tube. The fluid in 

 the test tube, outside of this chamber, usually remains clear. 



When cultivation has been successful, the bacteria may be obtained 

 either for morphological study or for further 

 cultivation, by simply allowing the fluid to 

 flow out of the little air-tight chamber back 

 into the test tube. The method is simple and 

 usually successful. 



Methods Based upon the Displacement of Air 

 by Hydrogen. The principle of air-displace- 

 ment by hydrogen, first utilized by Hauser, 1 

 has been widely applied to the cultivation of 

 anaerobic bacteria. In substance it consists 

 of the conduction of a stream of hydrogen 

 through an air-tight chamber in which plates 

 or tubes containing inoculated media have been 

 placed. 



For the production of hydrogen, the most 

 convenient apparatus is the Kipp hydrogen 

 generator. Hydrogen is generated from zinc 

 and sulphuric acid and this may be passed 

 through a series of "Woulf e-bottles, containing 

 solutions of lead acetate and of pyrogallic 

 acid, to remove traces of sulphuretted hydro- 

 gen and of oxygen, respectively, of Lugol's 

 solution to absorb traces of acid .vapor, and 

 of one with a silver-nitrate solution to take 

 up any hydrogen arsenide. 



For the preparation of anaerobic condi- 

 tions where very rigid anaerobiosis is neces- 

 sary, nitrogen may be used, which can be 

 bought in tanks from commercial firms. 



For anaerobic cultivation upon solid 



media, the inoculated tubes or plates are placed in an apparatus such 

 as the Novy jar. This is connected with the hydrogen apparatus and 

 hydrogen allowed to flow through it for five or ten minutes, and the 

 stop-cocks then closed. 



FIG. 35. WRIGHT'S 

 METHOD OF ANAEROBIC 

 CULTIVATION IN FLUID 

 MEDIA. 



1 Hauser, "Ueber Faulnissbakterien," 1885. 



