78 CULTIVATION OF ANAEROBIC BACTERIA. 



Roux plants a strict aerobe (Bacillus subtilis) on the top of 

 the anaerobic culture. The medium is boiled first, then 

 quickly cooled and inoculated. The top is covered with 

 sterile gelatin inoculated with the aerobe. The aerobe absorbs 

 the oxygen and the anaerobe develops in the bottom of the 

 tube where there is no oxygen. 



Gruber exhausts the air in the tube with an air-pump. 



Hueppe inoculates eggs in the shell through a very small 

 hole made with a hot needle. The opening is sealed with 

 collodion after inoculation. 



FIG. 31. 



Jar for anaerobic cultures. 



Fraenkel uses an ordinary test-tube stoppered with a rub- 

 ber stopper perforated by two holes, through which two glass 

 tubes are passed (Fig. 30). One tube is short, and the other 

 passes through the medium to the bottom of the test-tube. 

 Both glass tubes are bent at right angles above the stopper 

 and drawn out to a very small calibre, so that they can be 

 sealed easily. Hydrogen is passed into the tube through the 

 long glass tube and escapes through the short tube. After 

 five or ten minutes the projecting free ends of the glass tubes 

 are sealed at the places previously prepared for that purpose, 

 and the entire rubber stopper is covered with paraffin to pre- 

 vent entrance of oxygen and leakage of hydrogen. 



Novy uses a large glass-stoppered jar (Fig. 31) constructed 

 on the same plan as FraenkePs tube. 



