226 AGRICULTURE FOR BEGINNERS 



place, milk sours because bacteria from the air fall into the 

 milk, begin to grow, and very shortly change the sugar of 

 the milk to an acid. When this acid becomes abundant, 

 the milk begins to curdle. As I have said, the bacteria 

 are in the air, in water, in barn dust ; they stick on bits of 

 hay and to the cow. They are most plentiful, however, in 

 milk that has soured ; hence, if we pour a little sour milk into 

 a pail of fresh milk, the fresh milk will sour very quickly, 

 because we have, so to speak, "seeded " or "planted" the 

 fresh milk with the souring germs. No one, of course, 

 ever does this purposely in the dairy, yet people some- 

 times do what amounts to the same thing, that is, put 

 fresh milk into poorly cleaned pails or pans, the cracks 

 and corners of which are cosy homes for millions of germs 

 left from the last sour milk contained in the vessel. It 

 follows, then, that all utensils used in the dairy should be 

 thoroughly scalded so as to kill all germs present, and 

 particular care should be taken to clean the cracks and 

 crevices, for in them the germs lurk. 



In addition to this thorough cleansing with hot water, 

 we should be careful never to stir up the dust of the barn 

 just before milking. Such dusty work as pitching hay or 

 stover or arranging bedding should be done either long 

 before or after milking time, for more germs fall into the 

 milk if the air be full of dust. 



To further avoid germs, the milker should wear clean 

 overalls, should have clean hands, and above all should 

 never wet his hands with milk. This last habit, in addi- 

 tion to being filthy, lessens the keeping power of the milk. 

 The milker should also moisten the parts of the cow nearest 

 him, so that dust from the cow's sides may not fall into 



