EXPERIMENT STATION BULLETINS. 253 



file hands, neck of the jar, or other objects. If these precautious are 

 not exercised the benefit to be gained from the use of sterile milk will 

 not materialize. Under no condition should the cotton plug of a jar 

 be removed after the first heating, except when about to introduce the 

 starter, and then not longer than four or five seconds. 



Fig. 4. 



There are several factors which influence the time required for lop- 

 pering, viz., temperature, activity of starter, and quantity introduced. 

 In order to have a culture at the proper stage when needed the tem- 

 perature may be changed or the amount of the inoculating culture raised 

 to meet the requirements. Nothing but experience will determine these 

 points. 



