CHAPTER V. 



CnOTIVATION OF ANAEROBIC BACTERIA. 



None of tlie methods already described are suitable 

 for the culture of anaerobic bacteria, i.e. those bacteria 

 which thrive in the absence of oxygen. Numerous 

 special methods have been employed, more or less suc- 

 cessfully, but none of them are so convenient as the 

 ordinary method of plate culture used for aerobes. 

 Air can be excluded from the cultivation vessels 

 by means of some substance or other, such as oil, 

 gelatine, mica plates, etc., or it can be extracted by 

 the air-pump, or finally it may be replaced by another, 

 innocuous gas, such as hydrogen. 



Should it be necessary to separate anaerobes from a 

 mixture of bacteria, containing different species, vary- 

 ing one from the other as to their need of oxygen, it is 

 best to employ the last method, and to make use of 

 Esmarch's coated tubes. In order to study anaerobic 

 bacteria a small trace of the sediment from a foul 

 slimy ditch, or from a dung-heap, etc., is taken, and 

 a few drops of it are put into a few centimetres of 

 sterilised water : after these have been well mixed 



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