192 BACTERIOLOGY 



them. It forms diplococci and tetracocci, and shows 

 colonies on plate-cultures which are at first colourless 

 and later brownish, and which do not liquefy the gelatine. 

 In thrust-cultures a white, leaf-like layer is developed. 

 An iridescent greyish-white coating occurs upon agar, 

 while upon potato the growth is scanty. Some formation 

 of lactic acid accompanies its development. 



Sarcina cerevisiae. A number of sarcinae derived in part 

 from the air are found in beer. Lintner encountered a 

 variety in soured beer which, according to Adametz, occurs 

 also in water, and which sets up lactic acid fermentation. 

 Gelatine is not liquefied. The islets formed on plate-cultures 

 are round, colourless, and smooth-edged, and a delicate 

 fluorescent film develops gradually over the gelatine. 

 Thrust-cultures show a smooth white coating, and on 

 potato light granular islets form. 



Micrococcus viscosus. A peculiar disease of wine and 

 beer, called by the French la graisse, which consists in a 

 clouding and inspissation of the liquor, so that it becomes 

 stringy like white of egg, depends, according to Pasteur, 

 upon the vital activity of the Micrococcus viscosus. The 

 cells occur singly, or more usually arranged in diplococci or 

 streptococci. Artificial cultivation succeeds best in solu- 

 tions containing sugar. 



Bacillus viscosus cerevisiae. In viscous beer Van Laer 

 constantly found slender rods with no tendency to unite in 

 groups. Gelatine is liquefied. Upon plates there develop 

 round or oval colonies with uneven edges, which pro- 

 ject somewhat above the surface. In thrust-cultures a 

 white, irregularly-edged deposit is observed, while the 

 track of inoculation also shows an abundant development 

 of colonies. Growth on agar is very rapid, with the forma- 

 tion of a broad white slimy layer. These bacteria also occur 

 in milk and render it slimy. White, watery, and very tena- 



