144 GOOD HEALTH 



but also breathes with his mouth open all night, the cilia 

 have far too much to do : more dust gets in than they 

 can drive out, and it rushes past them, goes into the 

 most delicate tubes and air cells, stays there, and does 

 mischief. This explains black lungs. 



The other day a doctor told me that he had just 

 examined the lungs of a man who had died in Chicago. 

 He said that the man had always lived in the dustiest 

 part of the city, and that after he died, when the doctors 

 cut his lungs open, they noticed how dark they were. 

 Besides that, certain spots were as black as ink. 



No doubt the cilia had worked as hard as they could, 

 but the man had probably breathed in more dust than 

 they could drive out, and it may be he had breathed 

 with his mouth open. 



Though dust is bad enough, microbes in the lungs 

 are even worse. Yet how hard it is to keep microbes 

 out of the dust ! We learned that in the ninth chapter. 

 We also learned that microbes of consumption may give 

 the disease to healthy people and that we must do all we 

 can not to breathe them. 



In dusty streets and smoky places it is especially 

 important to breathe through the nose, because the nose 

 cilia will help the lung cilia; but in the very dustiest 

 places of all we should use a veil or a respirator to 

 sift out as much dust as possible. We should also avoid 

 talking in such places. 



