ANAEROBIC CULTURE METHODS 65 



CXXI. HESSKS METHOD. 



Pour some sterilized oil on the surface of a gelatine stab culture, 

 and the growth developing along the track of the needle is supposed 

 to be of an anaerobic nature. 



CXXIL LIBORIOUS^S METHODS. 



a. Fill a test-tube three-quarters full of gelatine or agar-agar, 

 sterilize, and place in a vessel of boiling water for ten minutes to 

 expel all air from it. Cool the medium rapidly in ice-water, when 

 FIG - 14 - between 30 and 40 C. and still fluid, inoculate, 

 solidify rapidly, and seal up the tube in the flame. 

 The anaerobic bacteria develop only in the lower 

 layers of the medium. 



b. For this method the special Laborious tube 

 is necessary (see Fig. 14). Hydrogen gas is passed 

 through the side tube by means of the hydrogen 

 apparatus, until all air is expelled (see Fig. 17, 

 p. 67). The contracted parts at the neck and side 

 of the tube are sealed in the flame, but owing to its 

 small capacity give better results with fluid media. 

 For the necessary precautions to be observed in 



Liborious's Tube for i i p -i nr, 



Anaerobic Cultures. USlllg hydrogen, S66 1&5. 



CXXIII. FILENKEL'S METHOD. 



1. Prepare a tube in the same manner as for a plate or Esmarch 

 roll culture. 



2. Replace the cotton by a sterile rubber stopper with two glass 

 tubes passing through it, and plugged with cotton wadding before 

 sterilization. The tubes on the outside of the stopper are bent at 

 right angles to the long axis of the test-tubes, and slightly drawn out 

 in the flame. One of the tubes reaches within 0'5 c. of the bottom of 

 the tube, while the other is cut off level with the inside of the stopper. 

 The hydrogen apparatus (see Fig. ^ 7, p. 67) is attached to the end of 

 the longest tube, and hydrogen allowed to bubble through the tube 

 until all air is expelled and its place taken by the hydrogen. The 

 hydrogen must be passed through the gelatine at least five minutes, to 

 ensure that all oxygen is expelled. The drawn out portions of the 

 tubes are sealed in the flame, and the protruding end of the rubber 

 stopper painted round with paraffin. 



