158 Dairy Bacteriology. 



butter, either in tubs or in prints. This trouble is easily 

 prevented. Butter is not well suited to the growth of 

 mold, but the paper used for lining the tubs, or wrap- 

 ping the prints is an excellent medium for mold growth. 

 The wood of the tub also furnishes ample food for this 

 type of life, especially where the wood contains any sap. 





PIG. 33. MOLDY BUTTER. 



The mold grows on the paper in which the butter is wrapped 

 rather than on the butter. The print on the left was 

 wrapped in the same paper as the print on the right except 

 that the parchment cover had been steamed for a few mo- 

 ments. 



One other essential condition for mold growth is a sup- 

 ply of oxygen. The mold spores are widely dissemi- 

 nated, and are always to be found on the butter tubs and 

 on the paper. The number is not likely to be sufficient 

 to cause trouble unless the tubs and paper have been 

 kept under such conditions, as to allow growth to take 

 place on them before use. During damp, hot weather, 

 the amount of moisture absorbed by these materials is 

 often sufficient to allow molds to grow on them. This 

 trouble can be prevented by the storage of tubs and pa- 

 per in a clean dry place, or by a disinfecting treatment 

 which will destroy the mold spores. The most success- 



