80 



CULTIVATION OF ANAEROBIC BACTERIA. 



50, and this is connected with a hydrogen apparatus by a rubber 

 tube, The hydrogen is allowed to bubble through the culture 

 liquid in a full stream for ten to fifteen minutes, in order that all of 

 the oxygen in the flask may be removed by displacement. Then, 

 while the gas is still flowing, the flask is sealed at a with a blow- 

 pipe flame, the hydrogen tube being left in position and melted fast 

 to the flask. Some little skill is required in the successful perform- 

 ance of the last step in this procedure, and it will be easier for those 



FIG. 49. 



Fia. 51. 



who are not skilful in the use ofthe blowpipe to use Salomonson's 

 tube, shown in Fig. 51. In this, hydrogen is admitted through the 

 arm b, and escapes through the cotton plug a. The vertical tube is 

 sealed at c while the gas is flowing, and then the horizontal tube at b. 

 Frdnkel's Method. Instead of these tubes specially made for 

 the purpose, an ordinary test tube may be used, as recommended by 

 Frankel. This is closed by a soft rubber cork through which two 

 glass tubes pass one, reaching nearly to the' bottom of the test tube, 



