230 BACTERIOLOGY 



rubber stopper carrying the glass tubes through which the 

 hydrogen is to be passed, and allow the hydrogen to flow 

 through as in the method first given. The gas now passes 

 over the gelatin instead of through it, and consequently no 

 bubbling results. In all other respects the procedure is the 

 same as that given by Frankel. 



Method of Kitasato and Weil. For favoring anaerobic 

 conditions Kitasato and Weil have suggested the addition 

 to the culture media of some strong reducing-agent. They 

 recommend formic acid or sodium formate, in 0.3 to 0.5 per 

 cent.; glucose in 1.5 to 2 per cent.; or blue litmus tincture 

 in 5 per cent, by volume. This is, of course, in addition to 

 an atmosphere from which all oxygen has been expelled. 

 As a reducing agent for this purpose, Theobald Smith regards 

 a weaker solution of glucose, 0.3 to 0.5 per cent., as more 

 advantageous; and Wright obtains better results when 

 glucose is added if the primary reaction of the media is about 

 neutral to phenolphthalein. 



Method of Park. A very simple, convenient, and effi- 

 cient method is employed by Park. It consists in covering 

 the medium in which the anaerobic species are to be cul- 

 tivated with liquid paraffin (albolene). The best results 

 are obtained when the amount of paraffin added is about 

 half that of the liquid in the tube or flask. The liquid paraffin 

 has the advantage over the solid paraffin in not retracting 

 from the walls of the vessel on cooling. All air is expelled 

 from flasks or tubes prepared in this way, by heating them 

 in the autoclave. The layer of paraffin prevents the reab- 

 sorption of oxygen driven off by the heat. After cooling, the 

 inoculation is made by passing the needle through the paraffin 

 well down into the media. 



Many other methods are employed for this special purpose, 

 but for the beginner those given will suffice. 



