178 MODERN" DAIRY PRACTICE. 



cilitated by introducing metal vessels in the creaming of 

 the milk. 



The weak point in this otherwise attractive method is 

 evidently the high temperature in the milk-room, for which 

 reason the milk also, according to numerous testimonies, 

 was very apt to sour. It is natural that the lactic-acid 

 bacteria under such conditions would get the upper hand 

 of other milk bacteria. Putrefactive and similar bacteria 

 had very poor chances of life in a Gussander milk-room. 



In the ice method, now generally used in our dairies, 

 light and cleanliness are the main weapons for fighting 

 the fermentation. But the bacteria are further checked in 

 this method by cooling the milk. As before stated, the 

 low temperature checks the growth and development of 

 the bacteria, but it does not kill them. If the cooling is 

 neglected or conducted so slowly that the bacteria present 

 in the milk or in unclean vessels are allowed to develop 

 and multiply before the temperature is low enough to stop 

 these processes, injurious changes in the milk or its prod- 

 ucts may sooner or later be observed. If the cream does 

 not become appreciably sour or of an undesirable flavor by 

 such manner of procedure, it will still be found that the 

 butter made from the cream is not of the good quality it 

 would otherwise have been. 



From the results obtained in the laboratory at Eiitti 

 (p. 88) we find how immensely quicker and stronger the 

 development of bacteria will take place in milk of 77 F. 

 than in milk 18 lower. If still lower temperatures had 

 been applied it would have been found, as in my experi- 

 ments (p. 89), that the development decreased more rapidly 

 the further the milk was cooled down, and that it stopped 

 entirely at 39 F. (4 0.). 



