BACTERIOLOGY OF MILK 219 



Stringy or Ropy Milk. When poured from a jug, ropy 

 milk takes a rope-like form. If a few drops are placed 

 between finger and thumb, and these separated, the ropy 

 milk draws out in a thread. Ropiness may be due to 

 milk coming from an inflamed udder ('garget' milk), in 

 which case the milk is unfit for food. In other cases, 

 where the bacteria concerned have an extracorporeal 

 origin, the milk, ' though abnormal, is quite wholesome, 

 and does not endanger public health ' (Board of Agri- 

 culture Leaflet No. 266). 



Water used for washing churns sometimes transmits 

 the organisms to the milk, or the cows may stand in 

 ponds containing them. They may be derived from dust, 

 straw, mouldy hay, and butterwort. 



The following organisms produce stringiness: 



B, lactis pituitosi (Loffler). A stout, slightly curved 

 rodlet, which does not liquefy gelatin (see below). 



B. lactis viscosus (' the viscid milk bacillus ' Adametz) 

 is a very short rod, aerobic, and does not liquefy gelatin. 

 Its effect is apparent after four or five days, and is con- 

 tinued for four weeks, by which time the milk corpuscles 

 have practically disappeared, and the milk is transparent. 

 The casein is not precipitated; no acceleration of the 

 process occurs on a rise of temperature, and there is no 

 special smell. 



Streptococcus Hollandicus is used in the manufacture of 

 Edam cheese. It does not liquefy gelatin; it renders 

 milk stringy within twelve to fifteen hours at a tempera- 

 ture of 77 F., the milk becoming sour at the same time. 



Norwegian taettemaelk is made with a ' stringy ' milk 

 bacillus. 



Soapy Milk. B. lactis saponacei (Weigmann and Zirn) 

 has been found in straw used as litter. It does not 

 coagulate milk, but makes it slimy and slightly ropy, with 

 a faint soapy taste. It grows best at 10 C. 



Slimy Milk is attributable to various organisms. Micro- 

 coccus viscosus (Schmidt-Miihlheim) is of 1 ^u diameter, 

 often occurs in wreathed chains of fifteen or more cells, 

 and produces a slime from the milk-sugar. The process 

 seems to differ from that of slime production in wine, 

 in that it forms no mannite and no carbonic acid. B. lactis 

 pitintosi of Loffler gives a specific smell, and renders the 

 milk slimy and slightly acid, especially at the lower part. 



