PASTEURIZING AND STERILIZING MILK 115 



incubator, and leave the other tubes with a tube of the fresh 

 milk at the room temperature. 



At the next exercise note carefully the condition of the milk 

 in each of the various tubes and also the number of colonies 

 on the agar plates. 



Keep the tubes of milk for further examination at the fol- 

 lowing exercise, noting any changes in their appearance, after 

 which they may be rejected. 



