The effect of altitude 



251 



body generally. To this absence Mosso attributed the symptoms of 

 mountain sickness, as Henderson (2) has more recently attributed the 

 effects of surgical shock ; this is, in fact, the "Acapnia theory." 



That the want of carbonic acid would, other things being equal, 

 affect the affinity of the blood for oxygen is, of course, clear from what 

 has been said in the earlier chapters of this book. This had not escaped 

 Bohr, who pointed out that the increased affinity of the blood for 

 oxygen in the presence of a diminished carbonic acid pressure in the 

 blood, would form a very beautiful adaptation on the part of the 

 organism to the rarefaction of the air. 



Here then was an obvious line of work. 



The results were so different from the predictions made by Bohr 

 that we have been at great pains to verify them. Inasmuch, however, 

 as we have obtained them with a number of different individuals 

 both in Teneriffe and on Monte Rosa, and as these results have been 

 confirmed by Haldane on Pikes Peak, it seems to be established 

 that so far from the blood gaining in affinity for oxygen by its loss of 

 CO.,, the affinity of the blood for oxygen remains as a first approxi- 

 mation unaltered in spite of the lowered CO 2 tension. 



The following are the carbonic acid tensions in the alveolar air of 

 various workers at various altitudes expressed in mm. 



The accompanying Figures 120 and 121 show the affinity of the blood 

 for oxygen at these different places and at different carbonic acid 

 tensions. The result is sufficiently astonishing ; whatever be the place, 

 the blood exposed to the carbonic acid pressure in the blood at that 

 place always possesses the same affinity for oxygen. It is different in 

 different people ; in Douglas's and Mathison's blood, for instance, it is 

 less than in that of Roberts, Camis and myself ; this does not matter, 

 the blood of each person has a certain affinity for oxygen, that affinity 

 remains almost unaltered. It was the same in Douglas's case at Orotava 

 with 41 mm. C0 2 pressure, at the Canadas with 35 mm. and at Alta 



