A STATISTICAL CLASSIFICATION OF THE COLON- 

 CLOACAE GROUP 



MAX LEVINE 



Iowa State College, Ames, Iowa 



Received for publication May 17, 1917 



It is now firmly established that the end products of metab- 

 olism, as well as morphological differences, are reliable and con- 

 venient indices for differentiation of bacterial species and 

 varieties. In the group of coli-like bacteria, particular attention 

 has been paid to acid and gas production fron various fermentable 

 substances. 



Theobald Smith (1893) observed that some B. coli ferment su- 

 crose and therefore recognized two forms. 



Durham (1901) suggested the name B. coli-communior for the 

 sucrose fermenting variety and characterized B. lactis-aerogenes 

 as a polysaccharid fractor. 



MacConkey (1905 and 1909), whose classification has been most 

 widely employed, subdivided upon gas formation from sucrose 

 and then from dulcitol thus giving 4 main types generally known 

 as the B. acidi-lactici type (sucrose negative, dulcitol negative) ; 

 the B. communis type (sucrose negative dulcitol positive); the 

 B. communior type (sucrose positive, dulcitol positive), and the 

 B. aerogenes type (sucrose positive, dulcitol negative). Under 

 each type are recorded a number of varieties according to gelatin 

 liquefaction, indol production, the Voges-Proskauer reaction, 

 motility, and fermentation of inulin, adonitol, etc. 



Very much along the lines of the MacConkey classification is 

 that of Bergey and Deehan (1908). They employed 8 characters 

 — fermentation of sucrose, dulcitol, adonitol, and inulin; gelatin 

 liquefaction, indol production, motility and Voges-Proskauer 

 reaction — and from a consideration of all possible combinations 



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