44 DUST AND ITS DANGERS. 



permanently in the tissues in such situations as 

 will least interfere with the action of the lungs 

 (see Fig. 4). Here it remains as long as life 

 lasts. 



FIG. 4. PIGMENTATION OF THE LUNG FROM INHALED DUST. 



A small portion of the surface of an adult human lung which has 

 become pigmented by the inhalation of dust. This drawing was 

 made not from the lung of a coal miner or one who had lived in 

 especially smoky or dusty places, but from that of an individual ex- 

 posed to the ordinary conditions of in-door city life. 



But we have not yet finished with the safe- 

 guards which the body has placed for itself 

 against inhaled dust. For, however success- 



