DUST AND ITS DANGERS. 47 



In answer to this, it should be said that not 

 only does the body afford the same safe-guards 

 against these living germs as against other 

 dust particles, as just described, but most of 

 the different kinds of germs which are floating 



FIG. 5. DUST FILTERS IN THE LUNG DEEPLY PIGMENTED. 



A drawing of one lobe of a human lung, showing the lymph filters 

 (lymph-glands) at one side, which have caught so much inhaled dust 

 in their meshes thus keeping it out of the blood as to have become 

 almost totally black. These glands are naturally of a light-pink color. 



in the air do not grow in the human body in 

 any appreciable degree ; the soil is not good 

 for them. Some do not find in the nose, or 

 the mouth, or the lungs, the proper food or 

 conditions which they need, others are actually 

 killed off sooner or later, either owing to some 



