CHAPTER VII. 



THE REAL SIGNIFICANCE OF DUST IN ITS RELA- 

 TION TO DISEASE. 



BUT why then, it may be asked, all these 

 sinister allusions to the danger of dust, 

 if, as we have seen in the last chapter, most of 

 it is caught before it gets into the lungs, and 

 that which does get in is disposed of in such 

 clever ways ? This question brings us at last 

 face to face with the gist of the whole matter. 

 The body does rid itself of a great deal of the 

 inhaled inorganic dust which lodges in the nose 

 and mouth and air-tubes of the lungs. It does 

 do the best it can to dispose of that which is 

 permanently stowed away in the lung tissues 

 themselves. It does without more ado kill out- 

 right or otherwise make way with most of the 

 living germs. But when all this is accomplished 

 there still remain certain important ways in 



