CONTAMINATION OF FOODS 141 



avoided as far as practicable, since-only by directing atten- 

 tion to all sources of contamination can the bacterial con- 

 tent of milk be kept at a low level. 



Contamination from the animal. The larger part of 

 foreign matter introduced into milk comes from the udder 

 and Hanks of the animal. In improperly constructed sta- 



Fig. 31. Dirt Tests 



A pint of milk was passed through each of the cotton filters. The amount of 

 dirt in the respective samples of milk is shown by the color imparted to the 



cotton 



bles, and where the bedding is not sufficiently abundant, the 

 flanks often become coated with manure. The udder may 

 also become soiled. If the yards are muddy, if the cows 

 have access to mud-holes or muddy streams, the udder and 

 teats will be soiled. Even on pasture the udder becomes 

 coated with dust. 



The extent of the contamination from the animal depends 

 on her condition as to cleanliness. It is impossible to draw 

 milk from a dirty animal without grossly contaminating it. 

 The farmer can not afford to clean soiled animals before 



