6i 

 EXERCISE XXI 



1 . Carefully sterilize two small top or covered pails. 



2. Select two cows standing near one another whose udders and 

 flanks are alike so far as amount of visible dirt is concerned. 



3 . Dampen with a cloth the udder and flanks of one of the cows 

 and milk her. 



4. Milk the other cow without dampening the flank and udder. 

 5r In a sterile bottle, take a sample of milk from each milking and 



plate the milk for bacteria. If the milk cannot be plated at once, the 

 bottle should be kept on ice. Compare the number of bacteria found 

 in the milk drawn under the two different conditions. 



