BACTERIA. 73 



symbiosis, so that the two species form a lichen-like 

 compound organism, which induces a " symbiotic fermen- 

 tation." 



5. SLIME-FORMING BACTERIA. 



Among the various species of slime-forming bacteria there 

 are several which are of peculiar interest in the fermentation 

 industries, as they occur in wine and fermenting wort, in which 

 they cause morbid changes. According to all analogy, this 

 slime formation may be regarded as a phenomenon closely 

 related to the commonly-occurring zooglcea formation of 

 certain bacteria (see p. 56). In the case of certain species 

 the slime is, however, also regarded as a product of the 

 decomposition of sugar, and not as a substance separated 

 from the organism itself. 



In the viscous fermentations examined by Bechamp a kind 

 of gum termed viscose was formed together with carbonic 

 acid, and frequently also mannite. 



In his "Etudes stir la biere" (Plate 1, Fig. 4) Pasteur 

 describes bead-like chains of spherical organisms, which 

 render wine, beer, and wort so viscous that they can be drawn 

 out in threads. 



In Berlin " Weissbier " (white beer), which had become 

 ropy, Lindner found a strong development of a certain 

 Pediococcus. The disease could be produced by adding 

 pure cultures to sterilised white-beer wort. On the other 

 hand, this organism had no action on hopped beer-wort or 

 low-fermentation beers. 



In ropy Belgian beer Van Laer found the cause of this 

 disease to be small, very thin rods (1*6 to 2*4 micro-milli- 

 meters long), which were partly isolated and partly united in 

 pairs by means of a zooglcea-like substance. When added to 

 beer-wort, this first became turbid, and afterwards ropy. On 

 meat decoction with gelatine these rods gave colonies with 

 concentric rings of different colours and with a hollow in 

 the middle ; streak cultures give broad, white bands, with a 



