Acid intoxication 279 



oxygen pressure in the alveolar air is higher than it would otherwise be. 

 This relative increase in the oxygen pressure has a twofold effect it 

 increases the rate at which the blood can acquire oxygen in the lung 

 and it increases the limiting percentage saturation. In effect it brings 

 you thousands of feet down the mountain again. So even from the 

 chemical point of view the blood is not under such bad conditions in 

 the lung after all. The meionexy reduces affinity of the blood for 

 oxygen, but indirectly betters the conditions for its acquisition. What 

 it takes away with one hand it gives back with the other. It is not 

 all loss in the lung and in the tissue it is all gain to the organism. 



The adaptation to altitude, being as I have said a compromise, 

 must break down if the conditions become too severe, that is to say, 

 if the altitude becomes too high for the necessary exercise, or the 

 exercise too great for the altitude ; the result is mountain sickness. 

 I have sometimes been asked the following question : If the effect of 

 altitude is merely to produce a given degree of meionexy with a less 

 degree of exercise, why are the final effects of exercise at low and 

 high altitudes different ? No one suffers from mountain sickness in 

 say the University Sports, though the effects of meionexy are evident 

 enough. Mountain sickness is doubtless caused by want of oxygen 

 in the brain itself. It is not merely that the vomiting centre is 

 stimulated by a meionectic condition of the blood in the general 

 circulation. At high altitudes even tissues which are comparatively 

 inert are suffering to some extent from oxygen want ; or at least 

 to prevent their so suffering there is some degree of dilatation. The 

 result of this dilatation, combined with faulty oxygenation of the 

 arterial blood, is to reduce the supply of oxygen of the medulla 

 to a minimum. Then some trifling change takes place ; the wind 

 meets you in the face and you hold your breath ; the digestion 

 of food, or perhaps even the contemplation of it, sends an extra 

 supply of blood to the abdomen ; sleeps comes and the blood 

 tends to leave his brain. Any of these will make you feel sick. The 

 actual symptoms of mountain sickness resemble those of haemorrhage 

 rather than of exercise. 



Is it possible to tell those who are likely to suffer from mountain 

 sickness from those who are not? It is difficult to say without 

 studying a much larger number of cases than those which have already 

 been subjects of research. In Teneriffe (1) the individuals whose 

 bloods had the smallest affinity for oxygen at a constant OCX pressure 

 suffered least from mountain sickness. Zuntz' and Douglas' blood, 



