52 Dairy Bacteriology. 



is drawn and exposed to the air of the barn during the 

 feeding operations, it is subject to the dust shower that 

 is present. Where the storage can is allowed to stand in 

 the stable during the milking, even though it is covered 

 with a strainer, this accumulation of microscopic par- 



' FIG. 15. CONTAMINATION FROM THE AIR. 

 This culture plate, three inches in diameter, was exposed for 

 30 seconds in the barn during feeding of dry fodder. A 12- 

 inch pail exposes over 18 times the surface of this plate. 



tides is added to the milk, as they readily pass the 

 meshes of the finest strainer. 



Removal of dirt after introduction. The more primi- 

 tive method of improving the quality of milk, so far as 

 its dirt content is concerned, is to attempt to remove the 



