MILK. 95 



different appearance in different localities that only after 

 specific investigations of the local bacteriological conditions 

 can there often be any question of applying them as decid- 

 ing factors. 



II. Bacteria Indifferent in Milk but Active in its Prod- 

 ucts. The species belonging to the second group which I 

 have met with will be described in later chapters. On 

 account of the many difficulties met with in the examina- 

 tion of these bacteria, I have unfortunately only to a small 

 extent been able to throw any light on their nature and 

 qualities. 



III. Indirectly Injurious Bacteria which Produce Fa- 

 vorable Conditions for Bacteria Injurious to the Milk. 

 The third group includes first of all several bacteria caus- 

 ing alkaline reaction in the milk. These bacteria may 

 play also a certain part in the dairy industry of Finland. 

 On a farm in Karelen, which I visited a couple of years 

 ago, I found the housewife almost in despair. She said 

 that tho milk had not soured properly during the whole 

 summer, and as a result inferior butter was made during 

 this time, while previously she had always prided herself 

 on making a mildly acid, first-class butter. Her supply 

 of butter on hand also showed that she had every reason to 

 be dissatisfied. The butter was mottled, insipid, and had a 

 repugnant taste. During the early part of the summer the 

 milk had soured, although it took a long time for it to 

 do so; now the souring did not seem to be forthcoming 

 at all. The milk stood in the pans for days, the cream 

 rose, but did not thicken. It did not taste sour, and 

 had no appreciable after-taste. Tested with litmus-paper 

 the milk showed a distinct alkaline reaction. I was 

 not able to investigate this interesting material bacterio- 



