222 BAOIBRIOLOGY. 



aerobic conditions Kitasato and Weil have suggested 

 the addition to the culture-media of some strong re- 

 ducing-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 ad- 

 vantageous; and Wright obtains better results when 

 glucose is added if the primary reaction of the media 

 is about neutral to phenolphtalein. 



Esmarch's method. Esmarch's plan is to prepare in 

 the usual way a roll-tube of the organisms ; subject it 

 to a low temperature, and while quite cold fill it with 

 liquefied gelatin, which is caused to solidify rapidly. In 

 this method the colonies develop along the sides of the 

 tubes, and can more easily be studied than when they are 

 scattered through the gelatin, as in the method of Liborius. 



Method of Park. A very simple, convenient, and 

 efficient method is employed by Park. It consists in 

 covering the medium in which the anaerobic species are 

 to be cultivated with liquid paraffin (albolene). The 

 best results are obtained when the amount of paraffin 

 aaded 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 auto- 

 clave. The layer of paraffin prevents the reabsorption 

 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. 



