THE DAIRY COW 147 



of the udder should also be kept scrupulously clean. It 

 should at least be brushed before milking. 



The milker should wear clean clothes and wash his hands 

 before milking each cow. The milk stool which is handled as 

 a rule with the same hand with which the milking is done 

 should also be clean. Sometimes milkers fasten the stool to 

 their body with a strap so as to avoid handling it. In up-to- 

 date sanitary dairies the milkers wear white laundered suits. 



Bacteria. Bacteria are very small living organisms. They 

 are so small that many of them can live in a particle of dust 

 that floats in the air. These are found everywhere. As 

 these germs get into the milk they grow, and they grow very 

 rapidly in warm milk. One of the waste products of these 

 germs is like an acid and it is this that makes milk taste sour. 



It is practically impossible to get milk from a cow without 

 getting some of these germs into it. But the thing to do is to 

 get as few into it as possible, and then as far as possible to 

 prevenl those that do get in from growing and multiplying. 

 This is done by cooling. 



Milk should be cooled as soon as it is drawn from the cow. 

 If it is to be separated, this should be done first and then the 

 cream should be cooled immediately. Milk and cream that 

 are thus handled will keep sweet for a long time. Sometimes 

 one hears it said that a thunderstorm makes cream sour, 

 but this is perfectly ridiculous. It is true, however, that 

 cream sours more readily at the time of a thunderstorm. 

 But such storms come in spells of hot weather and it is the hot 

 weather that makes the bacteria grow and these make the 

 milk sour. The same cause produces the thunderstorm, 

 namely, warm weather. 



If milk and milk vessels are not kept absolutely clean, 

 germs of contagious diseases such as typhoid may also get 

 into them. This will start epidemics of disease. To kill 

 any germs that may be in milk it should be sterilized. This 

 consists of heating it to a boiling temperature. Milk may 

 also be pasteurized. By this process it is heated to 145 degrees 

 Fahrenheit and kept there for about ten minutes and then 

 cooled rapidly. This kills most of the germs present in milk 

 and makes it keep much longer. But both sterilizing and 



