IX. 



CULTIVATION OF ANAEROBIC BACTERIA. 



PASTEUR (1861) first pointed out the fact that certain species of 

 bacteria not only grow in the entire absence of oxygen, but that for 

 some no growth can occur in the presence of this gas. Such bacteria 

 are found in the soil, and in the intestines of man and the lower ani- 

 mals. The cultivation of "strict anaerobics" calls for methods by 

 which oxygen is excluded. The "facultative anaerobics '' grow 



Fio. 47. 



FIG. 48. 



either in the presence or absence of oxygen. There are various gra- 

 dations in this regard, from the strictly aerobic species which re- 

 piiro an abundance of oxygen and will not grow in its absence, to 

 the strictly anaerobic species which will not grow if there is a trace 

 of oxygen in the medium in which we propose to cultivate them. 

 Among the most interesting pathogenic bacteria which are strictly 

 anaerobic are the bacillus of tetanus, the bacillus of malignant 

 and tin- ku-illus of symptomatic anthrax* 



