56 THE MILK QUESTION 



if the cows are not clean or the methods are otherwise 

 unsatisfactory. The dirt also comes from the dust in the 

 air, from the hands of the milker, from the pails, and a 

 thousand and one other sources. 



Many a farmer when told that his milk is dirty is incredu- 

 lous. When shown the dirt and told that it is cow dung, he 

 is frankly astonished, for to the farmer cow manure is not 

 dirt; in fact, it is the wealth of the farm. He has handled 

 it, worked in it, spread it upon his fields, has seen it pro- 

 duce his richest harvest, and has found no harm come 

 from contact with it. He cannot, therefore, understand 

 why so much fuss should be made about a little cow 

 manure in a bottle of milk. 



As a matter of fact, all dirt may not be harmful. There 

 is clean dirt and dirty dirt. But it takes a bacteriologist 

 to distinguish between them. Even cow manure from a 

 healthy animal may not be injurious, although it cannot be 

 recommended as a nutritive food for infants. We shall soon 

 see, however, that cow manure may contain tubercle bacilli 

 which have been swallowed by the cow or may contain 

 virulent streptococci and other harmful micro-organisms. 



The most harmful kinds of dirt which get into milk are 

 from human sources, as these are more apt to carry infec- 

 tion than any other. This kind of dirt is the more danger- 

 ous, as ordinarily it is invisible. Milk produced under 

 unsanitary conditions is not necessarily dangerous, but is 

 apt to be. 



Bacteria cling to dirt. About one half the weight of cow 

 manure consists of bacteria. Dirt in milk, therefore, is one 

 of the chief sources of high bacterial counts. The bacteria 

 favor decomposition and hasten souring. Dirty milk, 

 therefore, spoils much quicker than clean milk; in fact, 

 clean milk will keep two or three weeks without very much 

 trouble, while dirty milk sours in a day or two. It is, there- 

 fore, not only for sanitary reasons, but from an economic 

 standpoint that dirt should be kept out of milk. 



