CULTIVATION OF ANAEROBIC BACTERIA. 219 



Apparatus for plating out strictly anaerobic bacteria 

 that have met with great favor are those invented by 

 Botkin (Fig. 38) and Novy (Fig. 39). The first mentioned 

 combines the replacement of the air by hydrogen and the 

 absorption of the oxygen possibly remaining by alkaline 

 pyrogallic acid; the other simply replaces the oxygen by 

 hydrogen. In using Botkin' s apparatus the uncovered 

 Petri dishes are placed one above the other in the rack c, 

 and covered with the bell-glass A. Liquid paraffin is 

 poured in the dish b until it is about half full. From a 

 Kipp's apparatus hydrogen 

 gas enters the little rubber 

 tube a, subsequently escap- 

 ing by the tube b. When 

 only pure hydrogen escapes 

 the rubber tubes a and b are 

 withdrawn, and the appa- 

 ratus remains filled with hy- 

 drogen. Lest a little oxygen 

 should remain, it is best to 

 have the dishes at the top 

 and bottom of the rack filled 

 with alkaline pyrogallic 

 acid. Tetanus can be cul- 

 tivated in this apparatus. 



The jars recently intro- 

 duced by Novy are similar 

 in principle, depending 

 upon the replacement of the air by hydrogen. They are 

 so constructed that when the stopper occupies a certain 

 relative position to the neck the gas can enter and exit, 

 but when the stopper is turned a little the jar is hermet- 

 ically sealed. Alkaline pyrogallic acid in a test-tube, or 

 in the bottom of the jar, will serve to absorb any remain- 

 ing oxygen. The larger jar (Fig. 39, a) is intended for 

 Petri dishes, the smaller one (b) for test-tube cultures. 



Roux has suggested the simplest method of cultivating 

 anaerobic. bacteria. The germs are distributed through 



Fig. 38. — Botkin's apparatus for mak- 

 ing anaerobic cultures. 



