CULTIVATION WITHOUT OXYGEN. 



221 



which grew beneath it were supposed to develop with- 

 out oxygen. 



Hesse's method. Hesse poured sterilized oil upon the 

 surface of a culture made by stabbing a tube of gelatin. 

 The growth that occurred along the track of the needle 

 was supposed to be anaerobic in nature. 



FIG. 39. 



Liborius tube for anaerobic cultures. 



Methods of Liborius. Liborius has suggested two 

 useful methods for this purpose. One is to nearly (about 

 three-quarters) fill a test-tube with gelatin or agar-agar, 

 which, after having been sterilized, is to be kept in a 

 vessel of boiling water for ten minutes to expel all air 

 from it. It is then rapidly cooled in ice-water, and 

 when between 30 and 40 C., still fluid, is to be inoc- 

 ulated and very rapidly solidified. It is then sealed in 

 the flame. Anaerobic bacteria develop only in the lower 



