DUST AND ITS DANGERS. 43 



monary disease caused by the lodgment in 

 their lungs of foreign particles of one kind or 

 another, and furthermore, although even com- 

 paratively small amounts of foreign particles in 

 the lung tissue cannot fail to be undesirable 

 additions to those organs, still it is a fact that 

 the lungs do establish for themselves a consid- 

 erable degree of what we call tolerance of for- 

 eign particles lodged in their tissues. That is 

 to say, there may be a good deal of accumula- 

 tion of foreign material in the lungs without 

 any appreciable interference with the health, 

 because the body here, as in many other ways, 

 has the power of adapting itself to unusual and 

 even harmful conditions. 



In fact, the lungs of nearly all adults who live 

 under what we call civilized conditions, that is, 

 in houses with considerable smoke and dust in 

 the air, in cities which have street-cleaning done 

 for political purposes only, or in manufacturing 

 regions where there is much smoke, instead of 

 being of a delicate spotless pink color are dotted 

 all over with spots and streaks and patches of 

 inhaled dust-particles which the body has not 

 been able to get rid of but has stowed away 



