THE STORY OF THE BACTERIA. 



ordinary walks of life. We have seen already 

 by what comparatively simple means a large 

 part of the danger of the spread of tuberculosis 

 and diphtheria might be prevented. The risk 

 of dust infection from diphtheria, and probably 

 from other somewhat similar diseases, such as 

 measles and scarlet-fever, is more apt to be 

 limited to rooms or houses where the disease 

 has occurred, because the victims of these dis- 

 eases are usually sick enough to be confined to 

 the house or bed. But there are, as all physi- 

 cians know, frequently enough cases of these 

 diseases in which the patients go about among 

 their fellows throughout the whole course of 



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the illness, or at least for some time after it is 

 fully established. 



The possibility of dust infection with any 

 of the diseases which we have been consider- 

 ing, emphasizes the importance of breathing 

 through the nose and keeping the mouth shut 

 except when it is necessary to have it open. 



