68 METHODS OF CULTIVATION OF BACTERIA 



in a cylindrical jar of diameter sufficient to contain the tube 

 or tubes of media. The tubes are then inserted, potassium 

 hydrate solution (p. 65) is poured into the jar, and its mouth 

 quickly stoppered with a rubber or glass stopper. The stopper 

 is made airtight by sealing with paraffin. The pyrogallol 

 absorbs the oxygen in the jar, and thus the cultures are kept in 

 oxygen-free surroundings. 



Growth in Tubes ivith Pyrogallol-saturated Plug. Sloped 

 cultures can be maintained oxygen-free as follows : The medium 

 is placed in a long test-tube and inoculated. The plug of the 

 tube (which ought to be rather tight) is pushed down into the 

 tube, and a little dry pyrogallol placed on the top of it. A few 

 drops of the potassium hydrate solution are dropped on the 

 crystals, and a second plug is inserted in the mouth of the tube. 

 This is pushed home, and melted paraffin run on to the top to 

 prevent access of outside air. 



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. 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, 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 

 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 previously to 

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

 a little plug of co'tton 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 

 indiarubber tubing, and hydrogen is passed through for half an 



