20 THE BOOK OF CHEESE 



of coccus forms, commonly found in the air and in the 

 udder. Their presence in the milk may indicate direct 

 udder contamination. These are regarded as of little 

 importance, unless in very large number, and they 

 have been only partially studied. They produce little or 

 no lactic acid, and small amounts of acetic, proprionic, 

 butyric and caproic acids. These forms rarely create 

 enough acid to coagulate milk. 



28. Peptonizing organisms. This group includes all 

 bacteria which have a peptonizing effect on the milk. 

 It includes the acid peptonizing organisms, although 

 they are of primary importance in the acid type of bac- 

 teria, because the acid-producing power is greater than 

 the peptonizing power. Some of the specific organisms 

 in this class are Bacillus subtilis, Bacterium prodigiosus and 

 Bacterium liquefaciens. These are commonly found in 

 soil water and in fecal material. The presence of these 

 organisms denotes contamination from such sources. 

 <T 29. Inert types. As the name indicates, these are 

 organisms not known to have an appreciable effect 

 on milk. The ordinary tests fail to connect them with 

 important processes; hence they appear to feed upon, 

 but not to affect the milk in any serious way. Milk 

 ordinarily contains more or less of these organisms, but 

 no particular significance is attached to their presence. 



30. Alkali-producing bacteria. This group of organ- 

 isms has only recently been studied in relation to its 

 action on milk. Investigators still disagree as to the 

 usual percentage in the normal milk flora. Their pres- 

 ence in milk has been considered to be relatively un- 

 important. 



31. Butyric fermenting types. Organisms causing 

 butyric fermentation may be present in the milk, but 



