88 MILK [vi 



Slimy or Ropy Milk. Milk occasionally, in- 

 stead of exhibiting its ordinary limpid nature, be- 

 comes thick and slimy. Such milk either does not 

 cream at all, or else very imperfectly. It cannot be 

 churned, and is not suited for drinking purposes. 

 In some countries, however, as, for example, in 

 Norway, where it is really liked as an article of 

 diet (Tattemyelk) it is produced artificially by im- 

 mersing the stem of the butter -wort (Pinguicula 

 vulgaris) in the milk, or by feeding this plant to the 

 cows. Slimy milk is used in the manufacture of one 

 kind of cheese, viz. Edam. On the whole, however, 

 it is regarded as an unmixed evil, and has caused 

 great trouble in dairies. Various theories have been 

 put forward with regard to the cause of slimy milk : 

 but, like most other faults which we have mentioned, 

 it has been finally traced to the action of micro- 

 organisms. Pasteur was the first to discover that 

 there was a special yeast which had the power of 

 giving rise to a slimy fermentation of milk-sugar, 

 and thus gave a proper direction to the investigation 

 of the subject. Lister subsequently studied the 

 question of slimy milk, and attributed it to the 

 growth of bacteria. More modern researches on the 

 subject seem to show that slimy or ropy milk is 

 caused by a large variety of micro-organisms, among 

 which may be mentioned the bacillus mesentericus, 

 leuconostoc mesenteroides, actinobacter du lait visqueux, 



