468 MAN CONTROLS HIS ENVIRONMENT FOR HEALTH 



Practical Exercise 7. What methods of protection of water supplies are 

 employed by your community ? Visit the city water supply and report on its 

 conditions. Ask your teacher to give you references for Glenn's reports on 

 the water systems of certain cities in this country. Report on some one 

 system and compare it with your own city supply. 



Milk and disease. Another source of infection is milk. Fre- 

 quently epidemics have occurred which were confined to users of 

 milk from a certain dairy. Upon investigation it was found that a 

 case of typhoid had occurred on the farm where the milk came from, 

 that the germs had washed into the well, and that this water was 



used to wash the 

 ., -Q9\ milk cans. Once in 



,,--"*'* ~"-\ the milk, the bac- 



teria multiplied 

 rapidly, so that the 

 milkman gave out 

 cultures of typhoid 

 in his milk bottles. 

 Most large cities 

 now send inspectors 

 to the farms from 

 which milk is sup- 



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H^cCePark Dorchester "Milton. 



The small dots in the diagram show the number of cases of 

 diphtheria which occurred in three towns, among people who re- 

 ceived milk from dairy X. What may have been the reason 

 for the cases of diphtheria which occurred in H of Milton ? 



plied. These men examine and score the health of the cows, the 

 cleanliness of their surroundings, the health of the workers, the 

 care and construction of the utensils, and the methods of handling 

 the milk. Farms that do not attain certain standards of cleanli- 

 ness are not allowed to have their milk become part of the city- 

 supply. 



Care of a city milk supply. Besides caring for milk in its pro- 

 duction on the farm, proper transportation facilities must be 

 provided. Some of the milk used in Boston, Chicago, and New 

 York is forty-eight hours old before it reaches the consumer. Milk 

 used in the last-named city is said to come from eight states and 

 from Canada. During shipment it must be kept in refrigerating 

 cars, and during transit to customers it should be iced. 



Practical Exercise 8. What regulations are there in your community con= 

 cerning the farms from which milk is supplied ? Concerning the sale of milk ? 

 All but the highest grade milk should be pasteurized. Why? 



