238 



METHODS OF CULTIVATION 



prodigiosus upon the surface of the medium; or an 

 equal depth of liquefied gelatine, which is then inocu- 

 lated with the aerobic organism. 



3. Incubate. 



The growth of the aerobe will use up all the oxygen 

 that reaches it and will not allow any to pass through 

 to the medium below, which will consequently remain 

 in an anaerobic condition. 



(B) Method V.- 



i . Prepare tube or flask cultivations in the usual way. 



2. Replace the cotton- wool plug by 

 an india-rubber stopper perforated with 

 one hole and fitted with a length of 

 glass tubing which has a constriction 

 about 3 cm. above the stopper and is 

 then bent at right angles (Fig. 129). 

 The stopper and glass tubing are 

 sterilised by being boiled in a beaker 

 of water for five minutes. 



3. Connect the tube leading from 

 the culture vessel with a water or air 

 pump, interposing a WulfFs bottle 

 fitted as a wash-bottle and containing 

 sulphuric acid. 



4. Exhaust the air from the culture 

 vessel. 



5- Before disconnecting the appa- 

 ratus, seal the glass tube from the cul- 

 at the constriction, using the blowpipe 



Fl * 



ture vessel 

 flame. 



6. Incubate. 



(C) Method VI (Buchner's Method). 



Apparatus and Solutions Required. 



Buchner's tube (a stout glass test-tube 23 cm. long and 4 cm. 

 in diameter, fitted with india-rubber stopper, Fig. 130). 



Pyrogallic acid in compressed tablets each containing i gram. 

 Dekanormal solution of caustic soda. 



