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L. A. ROGERS, W. M. CLARK AND H. A. LUBS 



aerogenes group there are certain salient points which nearly all 

 bacteriologists will agree may be accepted as separating the group 

 into rather loosely defined subgroups or species. These may be 

 outlined briefly as follows: 



Characters common to the 

 ferment carbohydrates to 

 animals 



Dysenteric group 



Typhoid group. 



Paratyphoid, enteritidis group 



B. coll group 



B. aerogenes group 



B. cloacae group 



Proteus group 



group — short, thick, gram negative bacillus, tendency to 

 some degree; normal habitat, intestines of warm-blooded 



Acid from glucose and sometimes from mannitol 

 and sucrose. Indol, =*=, Carbinol reaction— 

 Characteristic serologic and pathogenic 

 properties. 



Acid from glucose and mannitol. Indol and 

 carbinol reaction — . Characteristic sero- 

 logic and pathogenic properties. 



Acid and gas from glucose, mannitol and dulci- 

 tol. Indol and carbinol reaction negative. 

 Characteristic serologic and pathogenic 

 properties. 



Acid and gas from glucose, lactose, mannitol 

 and sometimes sucrose and dulcitol. Volume 

 of gas relatively small. Indol usually posi- 

 tive, carbinol reaction usually negative. 



Acid and gas from glucose, lactose, sucrose and 

 usually from mannitol, but not from dulcitol. 

 Volume of gas greater than B. coli. Indol — 

 and carbinol reaction =■= . 

 f Characters very similar to aerogenes and in 

 \ addition gelatin is liquefied. 



Liquefies gelatin and under certain conditions 

 forms characteristic "swarming" colonies. 

 Acid and gas from glucose but lactose is not 

 fermented. 



A more definite classification of the colon-aerogenes group 

 is offered by the MacConkey arrangement which was adopted by 

 the laboratory section of the American Public Health Association. 

 This is purely an arbitrary classification based on the possible 

 mathematical combinations of positive and negative reactions 

 obtained with dulcitol and sucrose. It has no logical basis or 

 practical value. 



The data concerning the fundamental characteristics of the 

 several groups in this large family of bacteria is without doubt too 

 meagre at present for the establishment of a system of classifica- 



