The effect of altitude 261 



it may be that there is no increase of acid at all but rather a diminu- 

 tion in the amount of alkali present. From the point of view of the 

 dissociation curve the matter is of little interest, but from a wider 

 point of view it is of great interest ; so far we are left without a know- 

 ledge of mechanism of the adaptation which we have discovered. The 

 idea of oxygen want producing lactic acid is familiar enough ; were the 

 acid lactic, we should at once say that it had been produced in the 

 tissues as the result of oxygen want but we should be in another 

 difficulty for lactic acid is secreted by the kidney. If we found 

 it continuously in the blood we should expect to find it in largely 

 increased quantities in the urine. Ryffel tested this point and did 

 not find any great excess. 



Normal urine, sleep O'OOl / lactic acid 



Col d'Olen 9.15 p.m 7 a.rn 0-0012 



There seem to be two alternatives before us ; one is that oxygen 

 want under these circumstances produces acids in the tissues which 

 are not readily excreted : the other is that oxygen want so affects 

 the kidney that it excretes alkali more freely. Certainly Verzar's ex- 

 periments seemed to show that oxygen want did increase the activity 

 of the kidney. We are now entirely in the region of speculation, 

 however, so let us retrace our steps a little. 



A few lines back we spoke of the altered condition of the blood as 

 an "adaptation" to the altered conditions of barometric pressure. 

 In doing so we introduced a fresh idea into our narrative, namely, 

 that the change in the blood was beneficial to the organism. This is 

 true; so far we have treated the matter merely as an interesting 

 observation that the dissociation curve of the man remains constant ; 

 but the alteration of the individual factors while the balance is 

 preserved leads to a very important result. Over any considerable 

 interval of time there is always a certain relation between the CO 2 

 in the alveolar air and the oxygen in the same. 



The proportion of the one to the other depends upon the respi- 

 ratory quotient and ultimately upon the food that is eaten. If the 

 CO 2 changes the oxygen will change, so that if C v be the pressure of 

 CO 2 in the alveolar air and C A that in the atmospheric air, while O v 

 be the oxygen in the alveolar air and O A that in the atmospheric air, 



C C 



-7^- T~ will remain approximately* constant. 



* The determinations of C0 2 pressure in the alveolar air were made at the end of 

 expiration. To obtain the respiratory quotient more exactly a slight correction has 



