250 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



shorter tube a solution of caustic potash, the tube being corked as before ; 

 after 10 days at 37° C. the contents of the tubes are mixed, and no sign 

 of brown coloration occurs. 



Light bacteria may be used as oxygen indicators. The author refers 

 to the absolute anaerobic cultivation of Stiller, and to the extreme diffi- 



Inoculation 

 material 



ifS 



Rubber stopper 



Hygroscopic 

 cotton wool 

 stopper saturated 

 witb alkalin 

 pyrogallol 



Sterile dry plug of 



nou-hygroscopic 



wool 



:^r£ r ) Sterile broth 



Fig. 59. 



culty of attaining it, on account of the air adhering to the surface of the 

 glass culture tube and contained also in the medium ; these traces of 

 oxygen may be readily removed by employing an obligate aerobic micro- 

 organism, but the amount of oxygen may be too minute to enable the 

 light bacteria to emit light. By means of B. mesentericus the author 

 was able to free his medium from oxygen as quickly as with a light 

 bacterium. 



The author next considers the method of effecting a number of sub- 

 cultures in continuous oxygen-free condition. The apparatus (fig. 60) 

 is a development of the double culture tube (fig. 59), and consists 

 of 4 to 16 tubes, joined at the middle, the level of communication be- 

 tween succeeding tubes being higher than between those immediately 



