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 anaérobics” calls for methods by 
which oxygen is excluded. The ‘facultative anaérobics” grow 
Fic. 48. 
either in the presence or absence of oxygen. There are various gra- 
dations in this regard, from the strictly aérobic species which re- 
quire an abundance of oxygen and will not grow in its absence, to 
the strictly anaérobic 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 
anaérobic are the bacillus of tetanus, the bacillus of malignant 
cedema, and the bacillus of symptomatic anthrax. 
