336 A MANUAL OF BACTERIOLOGY 



VII. PURE FERMENTATIONS AND MICROBES. 



Frankland and Frew 1 have recently studied the 

 action of Bacillus ethacetosuccinicus (which they dis- 

 covered) on dulcitol and mannitol. The decomposition 

 of these substances may be regarded as involving two 

 independent reactions, viz. : 



(a) C 6 H 14 6 = 2 C 2 H 6 + C0 2 + CH 2 2 



(b) C 6 H 14 6 = C 4 H 6 4 + C 2 H 4 2 + 2H 2 ; 



but from the proportion which the acetic acid bears to 

 the alcohol, it appears that two molecules are resolved, 

 in accordance with equations a, for every one that is 

 decomposed according to b. Or, in other words, the 

 decomposition of either dulcitol or mannitol by this 

 microbe is represented by the following equation : 



3 C 6 H 14 6 = 4 C 2 H 6 + 2 CO, + 2 CH 2 2 + C 4 H 6 4 

 + C 2 H 4 2 +" 2 H 2 . 



The microbe which produces this change measures 

 from 1*7 to 2'5 //, in length and from 0'5 to 1 fju in 

 breadth. It occurs generally in pairs, and does not 

 produce spores. 



Frankland and Lumsden 2 have studied the decom- 

 position of mannitol and dextrose by Bacillus ethaceticus. 

 The products of the fermentation of both these com- 

 pounds consists of ethyl alcohol, acetic acid, hydrogen, 

 carbon dioxide, and traces of succinic acid. When the 

 fermentations are conducted in a closed <epace, there is 

 invariably also a considerable quantity of formic acid 

 produced, whilst in fermentations in an open space 

 (flasks plugged with cotton wool), formic acid, except 

 in traces, is a most exceptional product. The propor- 



1 Journal of Chemical Society, 1892, pp. 254-277. 



2 Proceedings of C/iemical Society, 1892, p. 70. 



