126 MILK TRADITIONS 



raises the temperature of the night's milk so 

 that the mixture is warm enough to allow bac- 

 teria to grow. There is no reason why a farmer 

 should not mix morning's and night's milk if 

 he can keep them both cold. At the shipping 

 station both morning's milk and night's milk 

 are usually mixed by the milk dealei , because 

 the dealer immediately cools the mixture and 

 puts it through his pasteurizer. If milk is kept 

 clean and kept cold, it makes little difference 

 whether it is morning's milk or night's milk or a 

 mixture of morning's milk and night's milk. 



THUNDERSTORMS 



It is believed by many that milk which was 

 sweet before a thunderstorm will be sour after 

 a thunderstorm, because of some influence, per- 

 haps the influence of electricity on the milk. 

 The truth is that the souring can be due only 

 to lactic acid produced by the growth of lactic 

 acid bacteria. These bacteria cannot grow well 

 in cold milk. They will grow well when milk 

 is not kept sufficiently cool. Since thunder- 

 storms come in hot weather, and hot weather 

 often interferes with the proper cooling of milk, 



