Effect of exercise on the dissociation curve of blood 239 



Moreover, as in the first of the two experiments upon myself which 

 I cited, Roberts' blood was tested by Mathison's method for the 

 degree of acidosis. At 17 mm.* oxygen pressure his blood when freed 

 from C(X was 55 / saturated, which, according to his curve, corre- 

 sponds to an added amount of acid equal to '029 % f lactic acid. 

 Now in this experiment the actual amount of lactic acid in Roberts' 

 blood was analysed by Ryff'el before and after the ascent. The blood 

 used was a portion of the same sample used for the gas analysis. The 

 method depends upon the conversion of the lactic acid into acet- 

 aldehyde, which is distilled off and estimated colorimetrically with 

 Schiff 's reagent. Before the climb commenced Roberts' blood con- 

 tained '014 % f lactic acid, at the end of the ascent it contained 

 *046 % f lactic, the difference '032 / corresponded within the limits 

 of experimental error to the acid added to the blood as indicated by 

 Mathison's method. 



Here then is a complete story. During the ascent, at the rate at 

 which Roberts made it, lactic and carbonic acids, and these only, are 

 added to the blood. The blood becomes meionectic, therefore the 

 respiratory centre is stimulated, the increased respirations cause the 

 excessive carbonic acid to be expired and not only the excess of 

 carbonic acid but somewhat more than this. The carbonic acid 

 pressure in the alveolar air therefore falls. The lactic acid, however, 

 is not got rid of so quickly as the carbonic acid, and is retained in 

 sufficient quantities to make the blood meionectic so long as the 

 exercise is taking place. We have no data which enable us to judge 

 of the subsequent duration of the meionexy 



So much for the facts : let us turn to their physiological significance, 

 that is to say to the consideration of the extent to which the changes 

 are beneficial to the organism or otherwise. 



First as regards the blood itself. The change in the curve suggests 

 a decrease in the value of K. (1) In the tissues each corpuscle will 

 lose its oxygen more quickly, other things being equal. (2) For a 

 given degree of reduction the pressure of oxygen in the capillaries 



* See Figs. 105 and 114. 



