CULTUEES OF ANAEROBES IN LIQUID MEDIA 67 



Cultures of Anaerobes in Liquid Media. — It is necessary to 

 employ such in order to obtain the toxic products of the growth 

 of anaerobes. Glucose broth is usually most convenient. It is 

 placed either (1) in a conical flask with a lateral opening and a 

 perforated indiarubber stopper, through which a bent glass tube 

 passes (as in Fig. 22 a), by which hydrogen may be delivered, 

 or (2) in a conical flask with a rubber stopper furnished with 

 two holes (as in Fig. 22, b), through a tube in one of which 

 hydrogen is delivered, while through the tube in the other the 

 gas escapes. The inner end of the gas delivery tube must in 

 either case be below the surface of liquid ; the inner end of 

 the lateral nozzle in the one case, and the inner end of the 



Fio. 22. 



a. Flask for anaerobes in liquid media. Lateral nozzle and stopper fitted 

 for hydrogen supply. &. A stopper arranged for a flask without lateral nozzle. 



escape tube in the other, must of course be above the surface of 

 the liquid. The single tube in the one case and the two tubes 

 in the other ought to be partially drawn out in a flame to 

 facilitate subsequent complete sealing. The ends of the tubes 

 through which the gas is to pass are previously protected by 

 pieces of cotton wool tied on them. It is well also to place 

 in the tube, through which the hydrogen is to be delivered, 

 a little plug of cotton wool. The flask being thus prepared, it 

 is sterilised by methods B (2) or B (3). On cooling it is ready 

 for inoculation. In the case of the flask with the lateral nozzle, 

 the cotton-wool covering having been momentarily removed, a 

 wire charged with the organism is passed down to the bouillon. 

 In the other kind of flask the stopfer must be removed for an 

 instant to admit the wire. (In the case of many anaerobes it 



