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lus, and a whole host of bacteria that sour or ferment the milk and 

 render it unwholesome or poisonous for young children. 



Cattle may be tuberculous, and the tubercle bacilli may reach 

 the milk in this way. There may be abscesses of the udder and the 

 streptococci from the pus may cause infection in those that use it. 

 Ordinary follicular tonsillitis may be caused in this way. 



Bacteria may develop rapidly in milk, which is a good culture 

 medium, until they number many million per cubic centimeter 

 (sometimes 200,000,000). 



In good milk the number of bacteria may increase when the tem- 

 perature is 90 F., from 5,200 originally in the milk immediately 

 after milking, to 654,000 in eight hours. 



By exposing milk to a temperature of 165 F. for twenty to thirty 

 minutes and quickly cooling (Pasteurization) most of the non-spore 

 bearing bacteria are destroyed, so that the number may be reduced 

 99.999 percent by this process. The pasteurization of milk has 

 become an economic problem of great importance in large com- 

 munities and is not, as it should be, sufficiently supervised. That 

 method is best in which milk is held at 146 F. for 30 minutes. 

 No harm is done to the nutritional value of the milk. Some 

 authorities maintain that bacteria grow no better in pasteurized 

 than in unheated milk, while others claim the reverse. More 

 evidence is on the side of the second view. The practical im- 

 portance of the controversy is that milk whether heated or 

 not should be kept at a temperature at which bacteria will not 

 multiply, under 60 F. Pasteurized milk is safest in time of 

 typhoid epidemic. 3 . 



Absolute cleanliness on the part of the milker, the use of sterilized 

 gloves and clothes, the absence of flies, dust, and the immediate 

 disposal of manure, the filtration of the milk after collection, the 

 immediate cooling of it, the uses of sterilized milk cans and bottles, 

 all lessen the bacterial content of milk. It then keeps better, and is 

 a wholesomer and safer food for infants, especially in hot weather. 



By drinking water containing typhoid bacilli cows cannot be 



