TYPHOID 359 



where the outbreak occurs, including its water supplies, its milk 

 supplies, the sociological relationships of its people, etc., he can 

 often tentatively determine the cause of the outbreak by a mere 

 inspection of the names and addresses of primary cases, especially 

 if plotted on a map of the community, taking into account also 

 the time of year, and other general points. But such deductions, 

 while often wonderfully reliable, can never be as conclusive and 

 satisfactory as are the results of an investigation by even a total 

 stranger, if the investigation be conducted as above described." 



REFERENCES. 



Savage, W. G.: The Bacteriological Examination of Water Supplies. 



Harracks, W. H. : An Introduction to the Bacteriological Examination of Water. 



Prescott and Winslow: Elements of Water Bacteriology. 



Thresh: The Examination of Water and Water Supplies. 



Mason: Water Supplies. 



Rosenau: Preventative Medicine and Hygiene. 



Don and Chisholm: Modern Methods of Water Purification. 



