THE RELATION OF MICROORGANISMS TO MILK 



439 



ATMOSPHERE OF STABLE AND MILK HOUSE. The atmosphere 

 of the stable may be an important factor in influencing the bacterial 

 content of fresh milk In well kept stables fairly free from dust this 

 source of contamination is usually not important but in stables where 

 the air is full of dust at time of milking, the germ content of the milk 

 may be appreciably increased from this source. In sanitary dairies 

 this factor is fully recognized and every effort is made to prevent the 

 presence of dust in the atmosphere at the time of milking. 



FIG. 141. Colonies developed from a bit of dust found in cow stable. 



culture. 



Agar plate 



THE MILKER. Not infrequently the milker himself is a source of 

 contamination. If his clothing and hands are dirty or if he brushes 

 against the cow, the dust thus dislodged may carry into the milk 

 large numbers of microorganisms. This is shown in the difference in 

 the germ content of milk drawn by two men milking in the same barn 

 under identical conditions. 



