146 AGRICULTURAL BACTERIOLOGY 



part of the dirt comes from the flank of the animal rather 

 than from the udder. The milking-machine is also an effec- 

 tive way of preventing the introduction of mud and dirt 

 into the milk, since the milk passes from the teat directly 

 into tubes that lead to covered pails. The effect that such 

 factors have in producing clean milk is dependent on the 

 condition of the coat of the animal. If the latter is very 

 clean, the use of the covered pail will have little, if any, 

 influence in improving the quality of the milk; but if the 

 animal is dirty, the influence will be great. The extent to 

 which any producer can apply methods for the prevention 

 of the contamination of milk is to be determined by the 

 results produced, and whether he can obtain compensation 

 from the consumer for the additional expense incurred. 

 Common decency, however, demands that the introduction 

 of visible quantities of mud and manure be avoided. Pre- 

 vention of contamination should begin with those operations 

 that will have the maximum effect. 



Influence of the milker. The milker should appreciate 

 the relative importance of the various sources of contami- 

 nation, and should know the most effective means of pre- 

 venting the introduction of microorganisms. The dress and 

 hands of the milker should be clean, and the methods of 

 milking such as to avoid contamination. Milking should 

 not be done with wet hands. If the conditions demand 

 something to soften the teats, vaseline may be used. The 

 whole hand should be used in milking, rather than stripping 

 with the thumb, and forefinger. 



Contamination from the utensils. It is difficult to clean 

 dirty utensils with sufficient thoroughness to remove all 

 traces of organic matter to the extent that bacterial growth 

 will not take pla.ce in case the temperature and moisture 

 conditions permit. The thoroughness with which the uten- 

 sil can be cleaned is dependent on the material of whicl/ 



