374 



'MICROBIOLOGY OE MILK AND MILK PRODUCTS 



they are faulty in construction. In open seams and other places the 

 milk may accumulate and not be thoroughly washed out. Usually 

 when utensDs of this sort are used, the methods for washing and ster- 

 ilizing are not sufficient and bacteria multiply in large numbers in the 

 cracks and crevices and contaminate each new lot of milk put into 

 them. Sometimes the utensils which are properly constructpd may 



Fig. 128. — Colonies developing from cow-hairs planted in agar plate. (Original.) 



contaminate the milk because they have not been properly cleansed 

 and sterilized. The use of steam is the most efficient means of ster- 

 ilizing all dairy utensils, but boiling water may give very satisfactory 

 results if used at actual boiling temperature. If not used at the boiUng 

 temperature some of the more resistant organisms will not be killed 

 and wiU be left to inoculate the fresh mOk. The ropy milk organism, 

 B. lactis viscosus, often remains in the utensils from day to day in this 

 way. 



