400 MILK 



of lactic acid to sterilized milk and then inoculating this milk 

 with pure cultures of various types of bacteria. It was shown that 

 some acid-tolerant cells of Bacillus coh could survive 0.6 per cent, 

 lactic acid, although the great majority of cells were destroyed. 

 Bacillus dysenteriae, B. typhosus, B. diphtherise, B. paratyphosus 

 B, and Spirillum choleras were destroyed by the presence of 0.45 

 per cent, lactic acid. However, there may be rare strains of 

 these bacteria that might survive this amount of acid. Since 

 buttermilk contains 0.7 to 0.9 per cent, acid, it is probable that 

 pathogenic bacteria are destroyed, and it may be assumed that 

 buttermilk is usually free from infection, even when prepared 

 from infected sweet milk. Similar results were obtained by 

 Penelope Marsh in 1918. 



Tatt^ Melk, Tattemjolk, or Kjernemelk 



Tatte melk, tattemjolk, or kjernemelk is a milk food pre- 

 pared in Norway and Sweden. It is a thick, viscous milk of 

 slightly cheesy taste and odor, and is eaten with a spoon. The 

 fermentation is started by adding to milk leaves of Pinguicula 

 vulgaris or a variety of Drosera, plants that grow abundantly in 

 these countries. A small amount of a previously finished product 

 is also used as starter, and sometimes pieces of linen are dipped 

 into the fermented milk which, after drying, will keep their fer- 

 mentative property for a long time and which are used if the 

 starter is sent by mail. The temperature most suitable for the 

 fermentation is body temperature. 



Troili-Peterson described but one organism as the active 

 agent in tattemjolk. This organism is a streptococcus and is 

 named by the authoress Bacterium lactis longi (the bacterium of 

 "long" milk). It resembles Bact. lactis acidi (Streptococcus 

 lacticus) , but forms less acid and produces a slimy consistency in 

 milk. Troili-Peterson states that she was unable to produce 

 normal tattemjolk in all trials with leaves from the plants men- 

 tioned. Alcoholic fermentation is insignificant because the tem- 

 perature of ripening is too high. 



There are three organisms in this milk that are responsible 

 for the fermentation, according to an investigation made by the 

 writer. A lactic streptococcus that differs from Streptococcus 

 lacticus by coagulating milk slowly and producing a stringy sub- 

 stance is probably the most important organism, and no doubt 

 the same one that Troili-Peterson has described. A yeast of the 

 morphology of Saccharomyces cerevisise is present and produces 

 the aroma. In pure culture the yeast ferments lactose and sac- 

 charose with violent gas format'ion, while from levulose gas is 



