THE LUNG MOVEMENTS. 95 



This extension of the subject has a practical bearing. The che- 

 mical view blinds us to the seeds of health and disease contained in 

 the atmosphere. We pound it into oxygen, hydrogen and carbon, 

 and find its ruins pretty invariable in all places under all circum- 

 stances. Plagues and fevers give a different analysis, and tell 

 another tale. They prove that the air is haunted by forcible elements 

 that resist segregation and distillation. The strokes of these airy 

 legions are seen, though the destroyers themselves are invisible. In 

 the atmosphere as a place of retribution, the cleanness or unclean- 

 ness of the ground and the people is animated by ever wandering 

 powers, which raise cleanliness into health, and filth into pestilence, 

 and dispense them downwards according to desert with an unerring 

 award. But who could guess this from the destructive analysis 

 into oxygen, hydrogen and carbon ; which misses out the great 

 shapes that stalk through the air, and laugh at our bottles and re- 

 torts often with a diabolic laugh ? But we shall recur to this sub- 

 ject when we treat of Public Health. 



To conclude this part of our subject, we have seen that the lungs 

 raise the blood into its principles, and discuss them on a higher 

 arena ; that they continually refresh and enlarge it by bringing it 

 into contact with the outward world in the shape of the atmosphere, 

 where at once it gives up its antiquities as the free breath unlocks it ; 

 that the lungs also humanize the air as it enters, and fill it with the 

 organic warmth and movements of the nose and the head. But 

 further, the blood, in passing into the lungs, is held as it were above 

 the body by virtue of the lightness of the sphere. And not only 

 in the lungs but everywhere in the system, the pulmonic levity, or 

 the rise of the surface, operates statically upon the fluids ; so that 

 each breath amounts to a posture or rather a hover of the entire 

 capillary blood and nervous spirit of the body. This levity-giving 

 is an intermediate function between the aerial and motor offices of 

 the lungs. We shall speak of it again at the end of this Chapter. 



We have now considered the chemical and physical functions of 

 the lungs, and glanced at their statical office ; it remains to treat 

 the second part of the subject, namely, the respiratory movements, 

 or the mechanics and dynamics of the lungs. 



That the effects of the lung movements are not small, a short 



