310 DISTRIBUTION OF BACTERIA 



from multiplying rapidly in the milk. The effect of tempera- 

 ture upon the rate of growth in bacteria is indicated by the 

 fact that if milk is kept at 50 F. for twenty-four hours, a 

 single germ may increase fivefold. If these same bacteria 

 are kept in milk at a temperature of 70, the increase is 

 720 fold. In the production of the milk, then, it is desirable 

 that the milk should be cooled immediately and the cooling 

 ought to be sufficient to take the milk below the tempera- 

 ture at which bacteria readily grow. Where it is possible, 

 a cooling apparatus should be installed and the milk 

 cooled to nearly the freezing point as quickly as possible, at 

 least within a fraction of an hour from the time of milking. 

 And the milk should be kept cool until it is ready to be used. 

 It should be iced during delivery and be kept cool after it is 

 delivered to the home. This is especially true of milk to be 

 used for infant feeding. 



