Sources of Bacterial Infection 179 



cine. Honest hygiene must be taught in 

 schools and colleges. Public-health officers 

 must know more about sanitation than about 

 politics, and there must be educational in- 

 stitutions where their special duties can be 

 learned. An enlightened public sentiment 

 must sustain them in their efforts to promote 

 the general welfare, even though the individual 

 may now and then be inconvenienced. 



But when efficiency shall have been secured 

 in the public-health administration, a large 

 responsibility will still rest upon the citizen. 



He can get clean food, pure water, and un- 

 polluted air by asking for them and insisting 

 that he have them. But he must insist, and 

 he must be vigilant. 



The danger of infection with disease-pro- 

 ducing bacteria which we may encounter in 

 the ordinary paths of life lurk, as we have 

 seen, for the most part, either in food, or air, 

 or water. Let us now look at these sources 

 of danger a little more closely. 



Food Infection 

 \Milk. This is such an excellent food for 



