A PAIR OF LIVING BELLOWS 121 



power stronger than our wills comes in and we have to 

 let go our hold. Very early in life we notice that when 

 we run hard, climb stairs, or lift heavy weights we breathe 

 quicker and more deeply. Bit by bit we found out that 

 our breath may be stopped by accidents of various kinds. 

 We may be caught in a crowd and our bodies so pinned 

 that we cannot expand our chests ; our chests are then in 

 the same fix as a pair of bellows with its handles locked 

 together. We may swallow something which is caught in 

 the throat or we may fall into a pond or river ; breathing 

 then ceases, because the passageway leading to the lungs 

 is blocked. A pair of lungs with a choked windpipe are 

 just as useless as a pair of bellows with a choked nozzle. 

 If we hold the valve open which guards the window on 

 the side of a bellows we find, when we work the handles, 

 that the air no longer enters and leaves by the nozzle but 

 by the large valvular opening on the side. Similarly, if a 

 large opening should be made in the wall of the thorax, 

 the breath no longer enters by the windpipe but by the 

 new aperture. The lungs then become collapsed, and 

 suffocation follows. 



There are accidents in which we may be choked and yet 

 the breath passages are not obstructed nor are the move- 

 ments of the thorax prevented. This happens when men 

 descend disused wells or mines and breathe foul air — air 

 with an insufficient amount of oxygen in it ; they die 

 of oxygen starvation. Were we to use a pair of bellows 

 filled with such air to blow up a fire, we should put it 

 out instead of reviving it. There is still another way 

 in which the human machine may be suffocated — one 

 which cannot be illustrated on an ordinary pair of bellows. 

 If for any reason the red discs cannot pick up their loads 

 of oxygen from the air chambers of the lungs, then 

 suffocation takes place. That may happen from many 

 causes : the blood channels to the lungs may become 

 blocked ; the great pump which drives the red discs along 

 may fail ; or the discs may become laden with certain 

 fumes, and therefore have no appetite for their regular 

 diet of oxygen, as in coal-gas poisoning. All these things 



