1. With unsalted butter made from pasteurized cream inoculated with various organisms and held at approximately 10°0., reworking after several days had the following effects:

a. The growth rates of bacteria frequently were increased.

b. The time required for development of defects commonly was decreased.

c. When butter culture was added to the cream, the pH values of the butter serum decreased more rapidly.

d. When lipolytic organisms were added to the cream, the acidities of the fat increased more rapidly.

2. The printing of butter in a type of equipment which subjected it to reworking tended to aggregate the moisture.

3. The reworking of butter may accelerate various microbiological changes in the product. Distributing organisms to previously uninfected moisture droplets and providing a greater food supply for certain of the organisms in the butter by aggregating the moisture are apparently of importance in this connection.