CULTIVATION OF ANAEROBIC BACTERIA. 131 



which remained (Fig. 32). His method was to place the 

 tube which had been inoculated in a much larger outer 

 test-tube containing alkaline pyrogallic acid. The large 



FIG. 31. Hesse's 

 method of making 

 anaerobic cultures. 



FIG. 32. Buchner's 

 method of making an- 

 aerobic cultures. 



F IG . 33. Frankel's meth- 

 od of making anaerobic cul- 

 tures. 



tube was closed with a rubber cap, and the absorption of 

 the oxygen allowed to progress. 



Gruber, instead of absorbing the oxygen as Buchner 

 does, prefers to use an air-pump and exhaust the contents 

 of the tube. He uses a tube having a slender neck and 

 a perforated rubber stopper. After the inoculation is 

 made the air is pumped out and the slender neck sealed 

 in the blowpipe. After this the tube can be warmed and 

 the melted gelatin or agar-agar rolled on its sides, as sug- 

 gested by Ksmarch, if desired. 



Better than any of the preceding is the method of 

 Frankel, which removes the air and replaces it by hy- 

 drogen. Frankel prepares an ordinary Ksmarch tube, 

 removes the cotton stopper, and replaces it by a carefully 

 sterilized rubber cork containing two tubes (Fig. 33). The 



