1 98 LACTIC ACID BACTERIA IN DISTILLING, ETC. 



varies between 0.5 and 50 /z. The thickness of the sheath is often ten times 

 greater than the diameter of the cell. When examined under the microscope, 

 this thick envelope with its comparatively thin enclosure resembles a worm, and 

 it is on this account that the name Bacterium vermiforme has been given to the 

 fungus. 



The bacterium is shown in Fig. 53. It stands in symbiotic relation with the 

 Saccharomyces pyriformis, so that the development of the one is facilitated by 

 the presence and vital activity of the other. Ward also succeeded'in artificially 

 constructing the ginger-beer plant from its two components. The chief products 

 of this fermentation are carbonic acid and lactic acid, in addition to traces of 

 alcohol and acetic acid. The lumps of the plant are kept in a state of saltatory 

 motion by means of the carbonic acid gas, and increase considerably in size during 

 the fermentation. They are able to withstand desiccation, and shrink up on 

 drying to form a horny mass, in which condition they are stored for future use. 

 The origin of the ginger-beer plant is unknown. 



