BACILLUS AMYLOBACTER 181 



Marpmann has also found the Sphserococcus acidi lactici 

 in milk. It possesses properties similar to those of the 

 Micrococcus acidi lactici. 



Clostridium butyricum, or Bacillus amylobacter. — This is 

 found in old milk, and is also very widely distributed 

 elsewhere in nature. It was thoroughly studied by 

 Prazmovsky. It is very often met with in cheese as well as 

 in putrid vegetable infusions, and is, as discovered by 

 Nothnagel, a very frequent inhabitant of faeces. The rods are 

 actively motile and strictly anaerobic, and develope in 

 gelatine and agar gases which smell of butyric acid. They 

 stain blue or dark violet in aqueous solution of iodine, from 

 which it has been concluded that the protoplasm must con- 

 tain fjranidose — hence the name Bacillus amylobacter. Bu- 

 tyric acid is formed from starch, dextrine, and salts of lactic 

 acid with simultaneous development of hydrogen and carbon 

 dioxide gas ; while masses of caseine and other coagulated 

 albuminoid bodies are liquefied. 



Micrococcus acidi lactici liquefaciens. — Kriiger has dis- 

 covered this micro-organism in caseous butter and in 

 cheese. It consists of small oyal immotile cocci, often 

 arranged in groups of four, and forms small colonies on the 

 gelatine plate, which speedily liquefy that medium. In 

 thrust-cultures there develops on the surface of the funnel- 

 shaped area of liquefaction a white pellicle, which later 

 sinks to the bottom. Milk curdles at 25° to 35° C, with 

 formation of lactic acid and separation of a clear serous 

 layer on the surface, while after a longer time a smell like 

 that of paste is given off. The micro-organism grows 

 whether air is excluded or not. 



Acidity and bitterness in milk may be also occasioned, 

 according to Kiihn, by the Proteus vulgaris, which causes 

 a thickening of the milk. 



Oidium lactis. — In sour milk, and constantly in butter, 



