136 A MANUAL OF BACTERIOLOGY 



The microbe in question is quite distinct from 

 the lacillus (giving a green fluorescence) which 

 Heraeus obtained from soil. 1 The bacillus of 

 Heraeus converts urea into ammonia, while Bac- 

 terium allii has no such action, for it decomposes 

 albuminoids (vegetal and animal) with the forma- 

 tion of a ptomaine among other products. 



Bacterium aceti. This is the microbe which 

 causes the acetic fermentation according to the well- 

 known reaction : 



C 2 H 5 OH + 2 = H 2 + CH 3 COOH. 

 It is about 1'5 //, in length, and occurs singly, in 

 long chains, and forms a pellicle on the surface of 

 the nutritive fluid. Although Pasteur maintained 

 that B. aceti was the cause of the acetic fermenta- 

 tion, and Cohn 2 observed the microbe largely in 

 sour beers, yet not until the commencement of 1886 

 could any one say with certainty that this microbe 

 was the real cause of the acetic fermentation. In 

 that year Mr. A. J. Brown 3 prepared pure cultiva- 

 tions of the microbe in question, and found that it 

 does convert alcohol into acetic acid or vinegar. 

 The author 4 entirely indorses the correctness of 

 Brown's researches. After obtaining pure cultiva- 

 tions of B. aceti by the fractional and dilution 

 methods, it was found that these cultivations, when 

 used to inoculate sterilised ethyl alcohol (6 per cent.) 

 gave acetic acid in abundance. 



1 Zeitschrift fur Hygiene, 1886. 



2 Biol. d. Pflanzen, Bd. ii. p. 173. 



3 Journal of Chemical Society, 1886, p. 172. 



4 Proceedings of Royal Society of Edinburgh, vol. xv. p. 46. 



