CONTROL OF THE PUBLIC MILK SUPPLY 445 



true that slovenly dairying, lack of refrigeration and age may individu- 

 ally or in combination produce high counts it is not essential although it 

 would be desirable to distinguish which, in any particular case, is re- 

 sponsible for high numbers of bacteria. Milk as drawn from the udder 

 normally contains few bacteria and these are of varieties that do not 

 multiply rapidly in milk, consequently if it contains large numbers of 



FIG. 62. Effect of temperature upon milk as shown by bacterial counts. 



Fig. 1. Original sample. 



42 F. 72 F. 



After 4 hours Fig. 2 Fig. 5 



After 9 hours Fig. 3 Fig. 6 



After 30 hours Fig. 4 Fig. 7 



(From the I4th. Annual Report of the Board of Health of the Town of Montclair, N. J.) 



organisms they must originally have been added in the milking or after- 

 ward and the milk is abnormal whether these germs are the result of 

 heavy contamination at the source or have developed from a slight con- 

 tamination because the milk has been kept at high temperatures or 

 because the milk is so old or stale that they have had time to grow in it. 

 It is the duty of those regulating the supply to see that milk as near 



