150 AGRICULTURAL BACTERIOLOGY 



disease-producing organisms that may thus be carried from 

 one farm to another. It has been found that the enhanced 

 value of the butter and cheese is more than sufficient to pay 

 for all cost of treatment. 



Factors determining the number of bacteria. The bac- 

 terial content of any sample of milk is dependent on the 

 number that have been introduced into it from the various 

 sources that have been considered, and on the extent to 

 which the bacteria have grown in the milk. It has been 

 shown that, under ordinary conditions, the utensil is the 

 most important source of contamination, and the animal the 

 next in importance. Even the most simple utensil that is 

 apparently in a satisfactory condition may add an unbe- 

 lievable number of bacteria to the milk. 



In seeking to improve the quality of milk from the stand- 

 point of contamination with bacteria, the utensils should 

 be considered first. Prevention of growth therein by the 

 complete removal of water should take precedence over at- 

 tempts to sterilize the utensils by steam, unless the steam- 

 ing can be so prolonged that the utensil will dry quickly 

 from the heat imparted to it. Steaming for a few seconds, 

 and leaving the utensil in a moist condition, defeats the 

 aim in view. Utensils in which no bacterial growth has 

 taken place, supplemented by wiping off the visible accumu- 

 lations of mud and manure from the udders of the cows, and 

 the use of small-topped pails, will prevent the entrance of 

 the major portion of organisms into the milk. 



The problem connected with the second factor, that of 

 the growth of bacteria in milk, must be solved by means to 

 be treated in a subsequent chapter. A high bacterial con- 

 tent does not necessarily mean a milk produced under un- 

 desirable conditions with reference to cleanliness, but it 

 does imply a milk of undesirable quality from the stand- 

 point of the consumer. 



