ANAEROBIC BACTERIA 161 



ence and absence of free oxygen were termed by Liborius 2 "facultative 

 anaerobes." It has also been observed by Pasteur that certain butyric 

 acid bacteria grow abundantly in the liquid medium, through which a 

 current of carbon dioxide is passed, but are destroyed, when a current 

 of air is passed for 2 hours through the liquid. Those organisms, which 

 are unable to thrive under partial oxygen pressure and cannot withstand 

 even small amounts of oxygen, were termed by Liborius "obligate an- 

 aerobes." Beijerinck 3 divided the bacteria into two groups, according 

 to their oxygen need: (1) "aerophile," or those requiring a high oxygen 

 tension, including the aerobes and facultative anaerobes, which can 

 grow in ordinary atmosphere; and (2) "microaerophile," or those organ- 

 isms that require a more or less low oxygen tension and do not grow 

 readily in ordinary atmosphere. The influence of oxygen on some bac- 

 teria was illustrated by the accumulation of the cells in a hanging drop 

 preparation; the aerophiles gathered in the outer zone, while the micro- 

 aerophiles massed together where the oxygen tension was least. The 

 spirillum type was intermediate. Burri 4 could not agree with this divi- 

 sion and suggested that the terminology of Liborius is much more 

 appropriate. Not only obligate anaerobic bacteria, but also the facul- 

 tative forms were able to live in the complete absence of oxygen for a 

 number of generations without being injured. 



No general minimum oxygen tension could be found for all obligate 

 anaerobic bacteria, but the various anaerobic forms varied in the limit of 

 this tension : 5 the oxygen limit for the blackleg bacillus (Bac. chauvoei) 

 is 1.04 per cent oxygen in the atmosphere, 0.65 per cent for Bac. tetani, 

 0.27 per cent for Clostridium butyricum and 0.13 per cent for Bactridium 

 butyricum; the obligate anaerobic bacteria could be so adapted as to 

 withstand some amounts of oxygen. Even many species which usually 

 grow in the complete absence of oxygen, such as Bac. amylobacter, can 

 thrive in the presence of oxygen. A typical obligate anaerobe has no 

 minimum oxygen tension limit, it is characterized by the existence of a 

 very low maximum oxygen tension and it can grow in the total absence 



2 Liborius, P. Beitrage zur Kenntnis des Sauerstoffbediirfnisses der Bakterien. 

 Ztschr. Hyg. 1: 115. 1886. 



3 Beijerinck, M. W. Ueber Atmungsfiguren beweglicher Bakterien. Centrbl. 

 Bakt. 14: 827-845. 1893; also Arch. Neerland., Ser. II, 2: 397. 1899; Pheno- 

 menes de reduction produits par les microbes. Ibid. 9: 131. 1904. 



4 Burri. R. Intramolekulare Atmung, Anaerobiose und Mikroaerophilie. 

 Centrbl. Bakt., II, 17: 804. 1907. 



5 Chudiakow, N. Zur Lehre von der Anaerobiose. Moskau. 1896 (Centrbl. 

 Bakt. II, 4: 389-394. 1898). 



