MICHIGAN ACADEMY OF SCIENCE. 16.5 



or ferment the sugar with the production of gas and other undesirable and 

 uncontrollable conditions. Sterilization was next resorted to in preparing 

 milk for the starter. Here all life was killed, thus leaving a clear field for 

 the action of cultures added. Restilts obtained in this way were more 

 satisfactory. The life of the starter was much prolonged, conseciuently 

 the cost less and the results obtained greatly improved in uniformity. 



In running a starter every precaution must be observed to keep it pure; 

 the difficulty with the ordinary methods of transferring, by pouring from 

 one vessel to the next, has been that after a few transfers the gas producing 

 bacteria, so common in the air of the factory predominate and our starter 

 is ruined. Methods were devised whereby small bottles or swabs were at- 

 tached to the end of a wire and sterilized with the milk. These were used 

 for transferring a small amount from one bottle to another from day to day, 

 care being taken as in the transfer of any bacterial culture. 



To run a starter by the latter method it is necessary to have sterile con- 

 ditions throughout for the building up and the transfer of the mother starter. 

 It is best to sterilize about a pint of milk in glass milk bottles. They should 

 be heated in running steam for thirty minutes each day for four consecutive 

 days. After cooling to below 100° F., it should be inoculated with a cul- 

 ture and placed at the proper temperature to develop in 24 hours. This is 

 the beginning of the mother starter, and is to be transferred daily into the 

 bottles of sterile milk by using one of the transferrers, before mentioned. 

 Whatever remains in the bottle is added to some pasteurized skim milk 

 which is allowed to sour and added to cream to be used for butter making 

 and to milk to be used for cheese making. The percentage to l^e added, the 

 temperature at which it is carried, and the length of time the ripening should 

 continue are matters controlled by conditions surrounding the operator. 



Agricultural College, Mich. 



