996 



Ropy Milk. 



[march, 



Group II. 



In addition to the pathogenic organism mentioned above are 

 many other types of lactic ferments. jB. lactis aerogenes has been 

 stated by O. Emmerling to be capable of making milk ropy, although 

 this organism is more generally known as a type of lactic ferment 

 closely resembling B. coli, and, like it, is dreaded by the cheese- 

 maker as causing "blown" cheese owing to its power of producing 

 gas. 



Other lactic bacteria, as Weigmann (30) has shown, can become 

 slime-producing. 



Bacillus lebenis. 



The writer has found, for example, that B. lebenis grown in whey 

 constantly makes it ropy. 



So much acid is produced that this ropy whey will keep for several 

 weeks without undergoing any other changes, although exposed to 

 inoculation by an abundance of other bacteria. 



Ordinary whey inoculated with this organism and kept at a suit- 

 able temperature in a cheese vat, was afterwards bottled, and though 

 the ropiness decreased in the course of a few weeks, the material 

 was kept for two years without going bad. 



Lange wei. 



The first experiments with this "starter" were made in the 'fifties 

 by a farmer at Assendelft in Holland, but it was not generally used 

 till 1887, when Boekel strongly recommended its use. Since that 

 time much work has been done on the subject, and Weigmann has 

 isolated a streptococcus from the mixed culture used in practice ; but 

 probably this organism is associated with others in the Lange wei, 

 which increases its ropy producing properties. 



Weigmann has isolated a similar organism from the commercial 

 products known as Taettemaelk (thick milk) of Norway and Filmjolk 

 (stringy milk) of Finland and Sweden, which are prepared as articles of 

 diet. There is a very widespread belief that these beverages are pre- 

 pared from the leaves of the Common Butterwort (Pinguicula vulgaris) ; 

 but although ropy milk is said to have been produced from the leaves 

 of this plant, Orla-Sopp (31), has shown that this plant does not 

 produce typical Taette. The writer also has not succeeded in attempts 

 to produce ropy milk in experiments with a few plants of Butterwort 

 from Derbyshire, and it is quite probable that the leaves of this plant 

 are not always infested with the organism. These forms of ropy 

 milk are produced by the combined action of several kinds of organisms 

 growing in a mutual relationship which is called "Symbiotic." The 

 milk is not only made ropy, but has also a certain degree of sourness 

 and considerable keeping properties. 



Outbreaks of Ropy Milk in the British Isles. — Most of the 

 above organisms have been investigated on the Continent 

 and in America, but there is reason to believe that ropiness is 

 of no less frequent occurrence in the British Isles. 



