SLIMY OR ROPY FERMENTATIONS OF MILK 279 



from the casein, which substance may be set free 

 in the serum or watery part in the milk, or 

 (3) from the presence of swollen gelatinous capsules 

 round the organisms. 



Possibly the slimy character of the medium is due 

 in certain cases to the enormous number of bacteria 

 developed in it. 



Many species or varieties of bacteria are capable of 

 producing varying degrees of ropiness in milk and 

 cream. In some instances the milk or the milk serum 

 becomes ropy in a few hours, in which case the cream is 

 of normal consistency: in most samples, however, generally 

 the change occurs only after a considerable period, and 

 is therefore a commoner phenomenon in cream, and 

 especially when the latter is raised in pans. Ropiness 

 is less frequent in " separator " cream. 



The slime-producing organisms which have been most 

 carefully investigated and described are referred to 

 below. 



(a) Streptococcus hollandicus, Scholl, known as the "Ropy 

 Whey" or "Lange Wei" organism, is a coccus which occurs in 

 pairs and longer chains. It is allied to the ordinary Str. lacticus, 

 and, like it, produces lactic acid, but has the additional 

 power of rendering milk stringy and capable of being drawn out 

 into long threads in from twelve to fifteen hours at a temperature 

 of 22 C. The slime appears to be a product of the albumin of 

 the milk. Ropy Whey is used as a "starter" in Holland in the 

 manufacture of Edam cheese. The colonies on milk-peptone 

 gelatine are very small : they do not liquefy the medium. 



(b) Micrococcus Freudenreichii, Guillebeau, is a very large 

 aerobic coccus, often nearly 2 /a, in diameter, which produces 

 stringiness in milk in a few hours at a temperature of 20 C. or 

 less. Its colonies on gelatine are very small, round, and white, 



