The effect of altitude 



255 



(1) Firstly then, what evidence have we that the blood changed, 

 apart from the C0 3 , as we ascended the Peak ? The simplest way of 

 attacking this problem is to expose the blood to equal CO 2 pressures 

 in the various places and determine its dissociation curves. In 

 Fig. 122 are given the dissociation curves of Douglas's blood, with- 

 drawn respectively at Orotava, Canadas and Alta Vista and, in each 

 case, exposed to 41 mm. C0 2 tension. 



10 20 



30 40 50 60 70 80 90 100 



100 



90 



10 20 30 40 



80 90 100 



FIG. 122. 



FIG. 123. 



FIG. 122. Dissociation Curves (I III) of Douglas's blood exposed to 40 41 mm. CO., 

 pressure: III at sea level, II at 7000 feet G, I at 11,000 feet <g). Blood taken at 

 7000 feet exposed to 36 mm. C0 2 , X at 11,000 exposed to 33 mm. CO 2 , O at sea level 

 exposed to 34 mm. C0 2 . 



FIG. 123. Lines as in Fig. 122. Douglas's blood at Oxford. +no lactic acid, O + 0-03 



0-04 / Q , and <g> +0-070-08 / lactic acid. 



The difference between them is clearly to be discerned ; with each 

 rise of altitude the curve is displaced somewhat to the right enough 

 to be seen. This suggests an increase in the acid radicles, or a 

 decrease in the bases of the blood. It becomes a matter of interest, 

 therefore, to see whether these curves could be imitated by the 

 addition of small quantities of acid to blood. Fig. 123 shows that 



