BACILLUS ACETICUS. 



389 



vg-ries considerably from 1*2 /u. upwards ; where the Morphological 

 rods are longer they are frequently hent at their ends. c 

 Spore formation takes place in a similar manner to that in 

 bacillus subtilis.-r-On nutrient jelly they form brownish- Cultivation. 

 yellow colonies, with sharp outlines and with dark, almost 

 opaque, centres ; the superficial colonies have the ap- 

 pearance of brownish-yellow, gelatinous drops lying on 

 the surface of the gelatine. 



Bacillus aceticus. 

 (Mycoderma 'aceti, Mycoderme du vinaigre, Essigpilz.) 



According to Hansen's investigations the bacteria Bacteria of 

 which have the specific property of transforming the fermentation. 

 alcohol of fermented liquors into acetic acid can be 

 obtained with the greatest certainty by placing lager 

 beer (for example the Copenhagen Carlsberg beer, con- 

 taining 4 per cent, of alcohol and 5 per cent, of extract) 

 in open vessels at a temperature between 30 and 

 34 C., best at 33 C. ; after two or three days a scum 

 is formed which con- a be 



sists almost entirely 

 of acetic bacteria, 

 while the fluid has 

 become muddy and 

 strongly acid. The 

 bacilli are short 

 rods, somewhat con- 

 stricted in their 

 middle, the ends of 

 the rods being cut 

 off at right angles 



to the long axis ; , two normal chains X 1180. 



tli Air OIVA ic o"Krmf b , chain with involution forms X 1180. 



r size is about c> > abnormal chain x about 20 oo. 

 the same as that of 



the lactic acid bacteria. A characteristic appearance 

 is their arrangement in long chains, which, often ex- 

 tend through several fields of the microscope. Some 

 'of the members of these chains show more or less 

 distinct variations ; they assume cylindrical, hour-glass, 



Fig ' ^- 



