CULTIVATION OF ANAEROBIC BACTERIA 71 



drawn, and the material thus obtained is further examined by 

 staining and animal experimentation. The bacteria are then 

 again cultivated by inoculating fresh gelatin, making stab- and 

 stroke cultures. 



Fig. 39. Types of streak cultures: i, Filiform (Bacillus coli); ;>, echinu- 

 late (Bacterium acidi lactici); 3, beaded (Streptococcus pyogenes); 4, effuse 

 (Bacillus vulgaris); 5, arborescent (Bacillus mycoides) (Frost). 



It is necessary to transfer the bacteria to fresh media about 

 every six weeks, as the products of growth and decay given off 

 by the organisms destroy them. Stroke and stab test-tube 

 cultures are more characteristic than plate cultures, as the 

 types in figures 38 and 39 show. 



CHAPTER XII 

 CULTIVATION OF ANAEROBIC BACTERIA 



SPECIAL methods are necessary for the culture of the anae- 

 robic variety of bacteria in order to procure a space devoid of 

 oxygen. 



Liborius's High Cultures. The tube is filled about three- 

 quarters full with gelatin, which is then steamed in a water- 

 bath and allowed to cool to 40 C., when it is inoculated by 



