60 SOURCE OF BACTERIA IN MILK. 



milk is dependent upon other factors beside the original con- 

 tamination. These factors are chiefly the age and the tem- 

 perature at which the milk is kept. Before we can under- 

 stand satisfactorily the effect of temperature and age upon 

 the bacteria of milk it will be necessary for us to consider 

 the kinds of bacteria that may be found in the milk. We, 

 therefore, turn now to the consideration of the types of milk 

 bacteria. 



