620 MAX LEVINE 



A small group of organisms which resemble B. aerogenes with 

 respect to gas formation from various carbohydrates etc., did 

 not give the Voges-Proskauer reaction, and were neutral to methyl 

 red after three days incubation at the body temperature. It 

 has been previously observed that some organisms do not give 

 the Voges-Proskauer reaction, and are not alkahne to methyl 

 red until the fifth or seventh day of incubation. These organ- 

 isms resemble very closely the B. gasoformans non-liquefaciens 

 described by MacConkey (1909) who records the Voges-Proskauer 

 reaction as positive or negative. As this name is a trinomial, 

 and consequently invalid, the group is included, for the present, 

 under B. aerogenes. 



Key to the more common species of aerobic or facultative non-spore-forming bacteria 

 which ferment lactose with gas formation 



A. Voges-Proskauer reaction negative, usually acid (at least not alkaline) to 



methyl red, with no reversion on long standing; indol usually positive; 

 polysaccharids (starch, dextrin, and inulin) negative. 



Coli group. 



I. Sucrose positive. 



a. Motile; dulcitol, glycerol, and salicin usually positive. 



1. B.communior. 



b. Non-motile: 



1. Salicin positive; dulcitol and glycerol usually positive. 



2. B. neapolitanus. 



2. Salicin and dulcitol negative, glycerol usually negative. 



3. B. coscoroba. 



II. Sucrose negative. 



a. Salicin positive, dulcitol and glycerol usually positive. 



4. B. coli. 



1. Motile var. communis. 



2. Non-motile. var. immobilis. 



b. Salicin negative; dulcitol usually negative. 



1. Motile; glycerol usually positive. 



5. B. Gruenthal. 



2. Non-motile; glycerol usually negative. 



6. B. acidi-lactici . 



B. Voges-Proskauer reaction positive; (occasionally only after long incubation); 



reaction to methyl red alkaline, or if acid at first, it reverts to a distinct 

 alkaline reaction after long incubation (7 days); indol, usually negative; 

 polysaccharids, starch inulin and dextrin, negative or positive. 



Aerogenes-cloacae group. 



