CLASSIFICATION OF ANAEROBIC BACTERIA 525 



The Committee of the Society of American Bacteriologists 

 (1920, classification first formulated in 1917) places in the family 

 (no. VII) Bacillaceae, sporulating rods, two divisions which are 

 ranked as genera. These are: 1. The genus "Bacillus Cohn 

 1872 Aerobic forms. Mostly saprophytes. Liquefy gelatin. 

 Often occur in long threads and form rhizoid colonies. Form of 

 rod usually not greatly changed at sporulation. The type 

 species is Bacillus suhtilis Cohn:" and genus 2: "Clostridium 

 Prazmowski 1880 Anaerobes or micro-aerophiles. Often para- 

 sitic. Rods frequently enlarged at sporulation, producing 

 Clostridium or plectridium forms. The type species is Clostri- 

 dium hutyricum Prazmowski." 



Breed, Conn and Baker (1908) commented at length on the 

 major divisions proposed by the Committee: "This family, for 

 the spore forming rods, has very good justification. The two 

 genera. Bacillus and Clostridium can probably be separated, but 

 whether on the basis of relation to oxygen or of shape of the 

 sporangium, the future must decide. Although relation to 

 oxygen is a very important physiological distinction, it must 

 be admitted that the selection of a physiological basis for the 

 separation of these two genera is rather unsatisfactory. It 

 places some of the polar-spored organisms in one genus, some 

 in another, and raises the question where to place facultative 

 anaerobes hke B. mycoides and B. cereus." These authors 

 proposed a family (5) : "Bacillaceae, rods producing endospores, 

 usually Gram-positive. Flagella, when present, peritrichous. 

 Primarily saprophytes secreting proteolytic enzymes. A few 

 parasites." This family would include the majority of the 

 anaerobes and many aerobes. 



Buchanan (1918, a and b) reclassified the bacteria, using 

 physiological characters far less than did the Committee. His 

 classification of the non-acid-fast members of the family Bac- 

 teriaceae, sporogenous rods, is as follows: Tribe 1. Bacilleae, 

 endosporogenous rods, with four genera: 1. Bacillus, Aerobic 

 rods, usually Gram-positive, as a rule Hquefying gelatin, spores 

 usually not distorting rods when formed. 2 and 3. Anaerobic 

 or micro-aerophilic usually: 2. Plectridium, spores produced at 



