CULTURE OF ANAEROBES IN LIQUID MEDIA 61 



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

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

 ated india-rubber stopper, through which a bent glass tube passes, 

 as in Fig. 24, a, by which hydrogen may be delivered, or (2) in 

 a conical flask with a rubber stopper furnished with two holes, 

 as in Fig. 24, 6, 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 the liquid ; the inner end of the lateral 

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



FIG. 24. 



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

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



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 previously 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 stopper must be removed for an instant to admit the 

 wire. The flask is then connected with the hydrogen apparatus 

 by means of a short piece of sterile india-rubber tubing, and 

 hydrogen is passed through for half an hour. In the case of 



