104 MICROBIOLOGY 



have been proposed for the study of these bacteria consist in 

 growing them under the following conditions: 



(1) In a vacuum, (2) by replacing the air with inert 

 gases, (3) by the absorption of oxygen, (4) by the reduction 

 of oxygen, (5) by expulsion of atmospheric oxygen by means 

 of various physical principles and mechanical appliances, 

 and (6) by the combined application of two or more of the 

 above methods. 



It should be borne in mind that the many methods which 

 have been introduced with specially devised apparatus for 

 the cultivation of anaerobic bacteria were introduced for 

 certain specific purposes. In order to obtain satisfactory 

 results, it is necessary that the methods employed for this 

 work should be chosen in accordance with the purpose of 

 their respective inventors. In order to facilitate the selec- 

 tion of methods the following classification has been made: 



1. The methods for the determination of the presence 

 of anaerobic bacteria in a given substance. 



2. Methods for isolating anaerobic bacteria. 



3. Methods for growing pure cultures of anaerobes on 

 different media. 



4. Methods for the propagation of pure cultures and 

 for the preservation of stock cultures. 



5. Methods for the preparation of toxins. 

 Although the number of methods for cultivating these 



organisms is very large, for ordinary work with pathogenic 

 anaerobic bacteria the following methods have proved, to be 

 quite satisfactory. 



Liborius l recommended the following method : Pour 

 into a test tube, Erlenmeyer fiask, or deep Petri dish a suffi- 

 cient quantity of nutrient gelatin or agar to form a layer of 

 from 5 to 10 cm. deep. Bcil the medium for at least five 

 minutes to expel the air, ccol down to a temperature of about 

 40 C., inoculate the medium, distributing the inoculating 

 material well through it. Care must be taken not to shake 



1 Liborius. Zeit. f. Hygiene, Bd. I (1886) p. 115. 



