THE VOGES-PROSKAUER REACTION 159 



doubted multiplication of B. aerogenes. As to the prevalence 

 of this organism he states, "In rivers, the period of time when 

 rain is common is characterized by enormous increase in the 

 number of lactis-aerogenes and yet we are perfectly certain that 

 the organism is rare in feces." 



These observations may be easily explained on the assumption 

 that B. aerogenes is a soil form. In a study of coli-like micro- 

 organisms of the soil, now under way by B. R. Johnson and 

 the author, preliminary tests have shown that a large propor- 

 tion of cultures react positively for the Voges-Proskauer test, 

 and are therefore of the aerogenes-cloacae group. 



ON THE FORMATION OF ACETYL-METHYL-CARBINOL FROM 

 DIFFERENT CARBOHYDRATES AND ALCOHOLS 



Acetyl-methyl-carbinol, like carbon dioxid and various acids 

 is a product of carbohydrate metabolism. The fermentation 

 of carbohydrates with acid and gas formation is generally ac- 

 cepted as a reliable basis for differentiation of B. coli. It is 

 possible that a study of the production of acetyl-methyl-car- 

 binol from various carbohydrates might also be of differential 

 significance. 



Harden and Norris obtained acetyl-methyl-carbinol by grow- 

 ing B. aerogenes or B, cloacae in peptone solutions containing 

 glucose, fructose, mannose, galactose, arabinose, isodulcite, 

 mannitol or adonitol, but this compound was not formed with 

 glycerol ethyleneglycol, or acetaldehyde. 



Ferriera, Horta and Paredes, studied the Proskauer reaction 

 (presumably the Voges-Proskauer reaction) with glucose, galac- 

 tose, maltose, lactose, sucrose, dulcitol, mannitol, and inulin. 

 The reaction was positive eight times out of 117 tests with 

 glucose, 7 times out of 48 tests with galactose, and twice in 48 

 tests with mannite. Practically all cultures gave traces with 

 lactose and maltose while with dulcitol and inulin the reaction 

 was invariably negative. These authors give an interesting table 

 in which B. coli, B. cloacae and B. aerogenes are differentiated 

 on the basis of the "Proskauer" reaction with different carbo- 



