BACTERIA. , 71 



itself as follows : the liquid gradually loses its brightness, 

 and when it is agitated filaments of a silky lustre rise from 

 the bottom, and the beer assumes a disagreeable odour and 

 taste. In cultures, the bacillus develops both in the presence 

 and absence of free oxygen. In nutrient liquids it ferments 

 the carbohydrates, and amongst them the saccharoses, without 

 previously inverting them. Amongst the fermentation pro- 

 ducts, lactic acid, acetic acid, and alcohol are especially 

 mentioned. The acids produced cause the precipitation of 

 nitrogenous compounds in the liquid, and these, mixed with 

 the bacilli, produce a cloudiness, consisting of lustrous fila- 

 ments. The nutritive mixture best suited to this bacterium 

 is an extract of malt mixed with agar and a small quantity 

 of alcohol. 



GROTENFELT has recently described some species which must 

 be regarded as new ones ; at any rate he could not identify 

 them with those described by HUEPPE and MARPMANN. Some 

 species were observed to yield alcohol in addition to lactic 

 acid by the decomposition of sugar ; he suggests that these 

 species may possibly play a part in the production of the 

 aroma of butter. 



E. KAYSER carried out an extensive chemical enquiry into lac- 

 tic acid fermentations, for which purpose he made use of pure 

 cultures of growths in milk, cream, beer, must, etc. It had 

 been previously known that the quantity of acid produced 

 varies, and also that the proportions between volatile and 

 non-volatile acids vary according to the species. This was 

 confirmed by KAYSER. He also found that growths of the same 

 species, when cultivated on the surface of the liquid, yielded 

 larger amounts of volatile acids than cultures developed at 

 the bottom of the liquid. 



The success attained by HANSEN'S pure yeast system . in the 

 fermentation industry has, of late years, led to the adoption of 

 the same principle in some dairies, and also in the acidification 

 process in distilleries. A brief survey of the progress made in 

 this direction may be attempted. 



As the mash in distilleries does not exceed a temperature 

 of about 70 C., so that the diastase may be preserved, many of 

 the germs adhering to the raw materials are not killed, but are 



