REGULATING THE HEAT 



151 



of flame is being constantly fed. We have seen how the 

 combustion chambers of the muscular engines are stoked. 

 We must refer again to these ultra-microscopic combustion 

 chambers in the cylinders of the engines of the human 

 body (see fig. 6, p. 37), for when we recall the fact that 

 muscles make up more than one-third of our total weight 

 it becomes evident that the combustion which goes on in 

 them has much to do with maintaining the warmth of our 



LIGHTED CANDL 



RUBBER DIAPHRAGM 



Fig. 36. — An inverted glass funnel, in which a lighted candle has been 

 placed, set upon a movable diaphragm. 



bodies. When we examine the living muscle cylinders 

 we see long processions of red blood-discs arriving in the 

 capillary tubes surrounding them. The red corpuscles 

 are packed with loads of oxygen, picked up in the walls 

 of the respiratory chambers of the lungs. We see these 

 red discs unburdened of their loads as they file through 

 the capillary fields which surround the muscle cylinders, 

 the oxygen being drawn into their combustion spaces. 

 At the same time there arrive, carried in the fluid part of 

 the blood, substances which serve the muscle cyclinders as 

 fuel. We know very well that the fuel and the oxygen 



