RELATION OF BACTERIA TO THE DAIRY. l8l 



to place the milk in cans and submerge them partly or wholly 

 in water for the purpose of keeping the milk cool. Of course 

 no bacteria can get through the cans, but experience has shown 

 that, in spite of the care given, some of the water will usually 

 get into the milk. There is abundance of evidence that the 

 water in which the cans are submerged is sometimes the source 

 from which a troublesome dairy infection is derived. Clean 

 water, and vessels cleaned with live steam, form the second 

 set of safeguards against troublesome dairy bacteria. 



The Air. Besides these two chief sources there are others 

 which furnish bacteria to a less extent. Some doubtless 

 come from the air. In earlier years it was thought that this 

 was a large source of contamination, but we now know that 

 the air is ordinarily of little importance, although sometimes 

 it has been found to be a source of trouble. One case of 

 soapy milk, for example, has been attributed to the air. If a 

 farmer throws a lot of hay down from his hay mow just be- 

 fore milking and allows his cows to feed upon it during the 

 milking, the dust thus distributed in the air will be a source of 

 considerable contamination to his milk. The remedy is, of 

 course, to feed earlier or later, and at all events not to stir 

 up a dust in the milking stall by the use of dry hay. If this 

 simple precaution is taken the air will not ordinarily be a 

 source of sufficient numbers of bacteria to cause trouble 



The Milker. The milker himself must be regarded as a 

 source of bacteria. The clothing of the farmer is always 

 filled with bacteria and his hair and hands are sure to be cov- 

 ered with them. His motions in the barn, especially dur- 

 ing the milking, will distribute them, so that they will be sure 

 to fall into the milk pail. To avoid this danger some of the 

 best dairies require the milker to wear special garments when 

 milking, and the milking clothes are carefully washed, in some 

 instances by steaming, each day. Of course, the milker is 

 also required to have scrupulously clean hands. 



