l86 AGRICULTURE OF MAINE. 



While bacterial dirt is invisible, and so escapes our notice, 

 it is just as much dirt in a milk as is the manure, hay. hair, 

 and earthy matters, which are so common. It is the most im- 

 portant kind of dirt in a milk, both from an economic point, 

 and from a health point of view. 



While physical dirt is never present in the milk as it comes 

 from the cow, some bacterial dirt is always present in the first 

 milk drawn from a cow, even if she is in the best of health; 

 and it is always present in the milk from a diseased cow ; 

 especially from one with a diseased udder; in which case the bac- 

 teria, which are causing the disease of the udder, are drawn 

 from the udder with the milk in countless numbers. 



We thus have to consider two sources of bacteria in milk, 

 i. e., those which are in the milk as it comes from the cow, 

 and those that enter it after leaving the cow. 



The bacteria in the first drawn milk from a healthy cow are 

 those that have worked up through the milk ducts from the out- 

 side of the teats, and are derived from dust and any matters 

 that have touched the moist ends of the milk ducts. They are 

 almost always harmless in so far as affecting health is con- 

 cerned ; but they may be the cause of economic loss to the farm- 

 er through rapid souring of the milk, unless precautions are 

 taken to inhibit their growth after they leave the cow. Aside 

 from the economic loss resulting from their presence, unless the 

 milk be at once cooled, we need not consider them. 



The milk from a diseased udder, whether the seat of the 

 disease be located within or on the outside of the udder, will 

 always contain the bacteria that cause the particular disease. 

 Most of these disease bacteria are able to set up either mild or 

 severe disease symptoms among the human users of the milk, 

 as well as among the calves. Thus tuberculosis of the 

 udder will result in the presence of the germs of this disease 

 in the milk, which may later cause the same disease among the 

 human or animal users of the milk. Ulcerative processes, 

 which pass so comjnonly under the name of "garget" deliver 

 their causative agent to the milk, and these streptococci, as they 

 are called, can set up varying degrees of sickness in the bodies 

 of the users of the milk. Many an epidemic of septic sore 

 throat, some with a long list of fatalities, have been traced to 



