CHAPTER XVIII 



THE EFFECT OF ALTITUDE ON THE DISSOCIATION CURVE 

 OF BLOOD CONSIDERED IN RELATION TO EXERCISE 



IN each of the two preceding chapters I have tried to draw 

 a picture, in one of the man who is taking exercise at ordinary 

 altitudes, in the other of the man who is at a high altitude but 

 not taking exercise. 



I have depicted the man who is taking exercise as meionectic ; his 

 blood is unusually acid, it takes up oxygen less readily than usual, it 

 parts with it more readily, while at the same time the change in the 

 reaction of the blood quickens the respiration and the heart beat. 



I have pictured the man living at a high altitude as possessing 

 blood of usual or almost usual reaction. Mesectic, or nearly so, his 

 blood contains an unusually small quantity of carbonic acid and an 

 unusually large quantity of other acid radicles. The diminution of 

 carbonic acid in the blood is reflected in the alveolar air with the 

 result that CO 2 pressure in the pulmonary alveoli is unusually low 

 and consequently the oxygen pressure is higher than it would other- 

 wise be. 



In the present chapter I wish to consider the effect of altitude 

 upon exercise. In a couple of words it is this : a given degree of 

 meionexy would be produced by a lesser amount of exercise at a high 

 altitude than at a low one, or, to put the matter in another way, 

 a given amount of exercise would produce a greater degree of 

 meionexy at a higher altitude than it would at a low one. 



We shall now give some account of the experiments on results of 

 which these statements are based. 



Our party had two mountain tracks as similar to one another as 

 we could make them, each was a climb of 1000 feet. The low level 

 course was at Carlingford, co. Louth. It has already been described. It 

 started from practically the level of the sea. Our high level course 



