ANAEROBIC CULTIVATION 



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fitted up like the Frankel tube described above. The ends 

 of the tubes are plugged with cotton- wool, and the whole 

 flask, cork, tubes and medium is sterilised. The 

 medium is inoculated from a recent culture by momentarily 

 removing the cork. Hydrogen is then passed through 

 from a Kipp apparatus, the 

 long tube being connected with 

 the hydrogen supply. After 

 passing for about half an hour, 

 the tubes are sealed off and the 

 flask is incubated. For con- 

 venience of sealing the tubes 

 should be drawn out slightly. 



As many organisms produce 

 gas during their growth, it may 

 be necessary to provide for its 

 escape, or the flasks may burst 

 owing to the pressure. This can 

 be done by adjusting a mercury 

 valve, and may be carried out 

 in a simple manner by a method 

 devised by the writer. " Yeast 

 flasks," which can be obtained 

 in various sizes, are made use 

 of, and are filled three parts full 

 with a 2 per cent, grape-sugar 

 bouillon. The neck is corked 



With a perforated rubber cork FIG. 13.-Yeast flask arranged 



for anaerobic cultivation. 

 (A, Fig. 13), through which a 



glass tube, B, passes to the bottom of the flask, projecting 

 two inches above the rubber cork and here plugged with 



JT OO 



cotton-wool. The lateral tube of the yeast flask is also 

 plugged with cotton- wool, care being taken that the 

 plugs are loose enough to allow air to pass freely. The 

 whole is sterilised and inoculated. The glass tube, B, 



