MICRO-ORGANISMS IN MILK 323 



while in the unprotected pails there were 2391 bacteria per cubic 

 centimeter. 



By-products of creameries and cheese factories are usually re- 

 turned to producers in the containers that the cream or milk 

 was delivered in. The skimmed milk and whey sometimes stand 

 for days in the cans or barrels before called for by their owners. 

 During this time fermentation and putrefaction sets in and flies 

 have free access to the products. It is obvious that under such 

 conditions cans and barrels are difficult to clean, and one careless 

 producer may thus infect the utensils of other patrons. This con- 

 dition needs particular attention, since it may become the means 



Fig. 152. — A mere pretense of a milk-house. Turkeys roosting around the 

 milk utensils. (Webster, Bull. No. 56, Hygienic Laboratory.) 



of spreading disease germs, especially the germs of bovine tuber- 

 culosis. It is, therefore, customary in the best creameries and 

 cheese factories to wash and steam the cans before returning 

 them to their owners. The same practice is carried out by many 

 dairies, since it is realized that steam is not available at many 

 farms. All by-products of creameries and cheese factories should 

 be pasteurized as soon as possible, so as to prevent decomposition 

 and the spread of disease germs. A pasteurized by-product has 

 the additional virtue of being more suitable as food for farm 

 animals than a fermented or putrefied product. 



The evidence shows clearly that the bacterial content of milk 

 may be considerably increased if utensils are not properly cared 



