THE CULTIVATION OF BACTERIA. 



91 



bottle or tube which can be tightly stoppered, pour 10 c.c. of 

 a 6 per cent, solution of sodium or potassium hydroxide, for 

 each 100 c.c. of air contained in the jar. Add one gram of 

 pyrogallic acid for each 10 c.c. of solution. The culture-tube 

 is placed inside of the larger bottle or tube, supported above 

 the bottom, and the stopper, smeared with paraffin, is inserted. 

 The mixture of pyrogallic acid and 

 potassium hydroxide possesses the pro- 

 perty of absorbing oxygen. 



Wright's Modification of Buchner's 

 Method. — The tube of culture-medium 

 is to be plugged with absorbent cotton, 

 using a plug of large size. The culture- 

 medium is inoculated in the usual way. 

 The plug is cut off close to the neck of 

 the tube, and is then pushed into the 

 tube about i centimeter. Now allow a 

 watery solution of pyrogallic acid to run 

 into the plug, and then a watery solution 

 of sodium or potassium hydroxide. 

 Close quickly and tightly with a rubber 

 stopper. Wright recommends that the 

 first solution be freshly made and consist 

 of about equal volumes of pyrogallic 

 acid and water, and that the second 

 solution contain i part of sodium hy- 

 droxide and 2 parts of water. With 6-inch test-tubes, f-inch 

 diameter, the amounts advised are— J c.c. solution of pyrogallic 

 acid, I c.c. solution of sodium hydroxide. 



Cultivation of Anaerobic Bacteria under Hydrogen: Method of Liborius 

 Modified by Frankel. — A test-tube containing a large amount of the liquefied 

 culture-medium is closed with a sterilized rubber stopper, through which pass 

 two sterilized glass tubes, bent above the stopper at a right angle. One of these 

 tubes is cut off just underneath the stopper, and the other is long enough to 

 project nearly to the bottom of the culture-tube. The horizontal projecting 



Fig. 29.- 

 anaerobes 

 method. 



FT-ankel's 



