APPLIED PHYSIOLOGY 



simple view was disproved, physiologists shifted their 

 ground, and declared that the combustion process took 

 place, not in the lungs, but in the blood. Finally, and 

 in comparatively recent years, the correct notion was 

 arrived at, as the result of indisputable experiments, that 

 the utilization of oxygen and the production of C0 2 take 

 place in the tissues themselves. In other words, the 

 tissues control their own respiration. Supply a man 

 with more oxygen, and you do not necessarily ' burn up ' 

 his tissues one whit, though a candle under similar 

 circumstances will be consumed faster. The cells simply 

 ignore the excess of oxygen, even if it does not actually 

 "lessen their vitality, as the experiments of Paul Bert 

 would seem to indicate. The acceptance of this view 

 has modified profoundly some of our fundamental 

 pathological notions. In consequence of it we no longer 

 believe that the high temperature of fever is the result 

 of an increased * combustion ' in the lungs, and that a 

 free supply of food must necessarily be injurious under 

 such conditions. It implies, too, that the regular 

 practice of * deep breathing,' which is so much vaunted 

 by some professors of personal hygiene, is no substitute 

 for exercise. The latter alone can really increase the 

 oxidation processes in the body. 



In the lymph which actually bathes the cells there is 

 almost no free oxygen. Indeed, its presence in even 

 small amount seems to exercise a depressing influence 

 on cell activity. It is for this reason that, at pressures 

 of even 5 atmospheres of air, oxygen, instead of being 

 a stimulant, is actually poisonous to the tissues after 

 long exposures. 



