THE RELATION OF MICROORGANISMS TO MILK. 303 



THE UTENSILS. If properly cared for, the dairy utensils should not 

 add to the germ content of the milk. Not infrequently, however, they 

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

 may accumulate and not be thoroughly washed out. Usually when 

 utensils of this sort are used, the methods for washing and sterilizing 

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

 and crevices and contaminate each new lot of milk put into them. Some- 

 times utensils which are properly constructed may contaminate the milk 

 because they have not been properly cleansed and sterilized. The use 

 of steam is the most efficient means of sterilizing all dairy utensils, but 

 boiling water may give very satisfactory results if used at actual boiling 

 temperature. If not used at the boiling temperature some of the more 

 resistant organisms will not be killed and will be left to inoculate the fresh 

 milk. The ropy milk organism, B. lactis viscosus, often remains in the 

 utensils from day to day in this way. 



WATER SUPPLY. Sometimes the water used for washing the dairy 

 utensils is a serious source of contamination. Serious epidemics of dis- 

 ease have been traced to this source where the utensils were washed with 

 water contaminated by typhoid or other disease organisms and were not 

 sufficiently sterilized to kill those remaining in the utensils. Such dairy 

 troubles as ropy milk and gassy milk may be caused by the water used for 

 washing puposes. 



METHODS OF PREVENTING CONTAMINATION OF MILK. 



INDIVIDUAL Cows. Normally the number of microorganisms found 

 in the udder is not sufficient to be a serious source of contamination for 

 market milk. There are, however, certain cows which have a much 

 higher germ content than others, and where a very low count is desired 

 in the milk it may sometimes be advisable to eliminate such cows from 

 the herd. 



CARE OF THE Cow's BODY. In order to reduce to the minimum the 

 contamination from the cow's body she should be kept as clean as possible. 

 Dust should not be allowed to accumulate in her coat. It is well to keep the 

 hair of the flank and udder clipped in order to prevent the accumulation 

 of dust and also to facilitate the process of cleaning. The use of a damp 

 cloth for wiping the flank and udder at milking time is a very efficient 

 means of reducing this source of contamination. The beneficial effect 

 of this method may be seen in the following table: 



