Milk Fermentations. 61 



gan which he traced to an external infection from the 

 udder. In another case, he found the slimy germ in the 

 dust on the floor of a barn. Guillebeau 1 has reported a 

 number of cases in which slime-forming organisms were 

 traced to a diseased condition of the udder. 



In Switzerland, the chief cause of ropy milk seems to 

 be Mic. Freudenreichii, a large, immotile, non-liquefying 

 coccus that grows well at ordinary temperatures. This 

 organism is readily killed by heat, two minutes at 212 F. 

 being sufficient, but in a dried condition it has great 

 resisting powers. 



The .slimy substance formed in milk comes from vari- 

 ous ingredients of the milk, and the chemical character 

 of the slime produced also varies with different germs. In 

 some cases the slimy material is merely the swollen outer 

 cell membrane of the bacteria themselves; in others it is 

 due to the decomposition of the proteids, but in general, 

 the chief decomposition product appears to come from a 

 viscous fermentation of the milk-sugar. 



Normally this class is repressed by the development of 

 the lactic acid bacteria; in fact, putrefactive processes sel- 

 dom occur where the lactic organisms are in the ascend- 

 ency. In sterilized or pasteurized milk this competition 

 is removed as the lactic forms are unable to withstand 

 this treatment, while this enzyme-forming group sur- 

 vive by virtue of the spores which they possess. They 

 gain access to the milk not infrequently from manure 

 particles 2 that are derived from the coat of the animal. 



60. Favorable slimy fermentations. While in this 

 country slimy milks are considered as undesirable, yet in 

 certain parts of Europe changes of this character are put 

 to good use. In Holland it has long been the custom to 



1 Guillebeau, Landw. Jahr. d. Schweiz, p. 27, 1890. 

 * Backhaus, abs. in Expt. Stat. Rec., 10: 89. 



