CULTURES OF ANAEROBES IN LIQUID MEDIA. 69 



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 flask (i), the lateral nozzle is plugged with 

 molten paraffin covered with alternate layers of cotton wool 

 and paraffin, the whole being tightly bound on with string. 

 The entrance tube is now completely drawn off in the 

 flame before being disconnected from the hydrogen 

 apparatus. In the case of flask (2), first the exit tube and 

 then the entrance tube are sealed off in the flame before 

 the flask is disconnected from the hydrogen apparatus. It 

 is well in the case of both flasks to run some melted paraffin 

 all over the rubber stop- 

 per. Sometimes much gas 

 is evolved by anaerobes, 

 and in dealing with an 

 organism where this will 

 occur, provision must be 

 made for its escape. This 

 is conveniently done by 

 leading down the exit 

 tube, and letting the end 

 just dip into a trough of 

 mercury (Fig. 24), or into 

 mercury in a little bottle 

 tied on to the end of the FlG - 24- -Flask arranged for culture 



, . of anaerobes which develop gas. 



exit tube. The pressure 3 is trough of mercury into which exit tube dips. 



of gas within causes an 



escape at the mercury contact, which at the same time acts 

 as an efficient valve. The method of culture in fluid media 

 is used to obtain the soluble products of such anaerobes as 

 the tetanus bacillus. In employing such a method the 

 removal of the air may be accelerated by using an air-pump 

 as described above. 



