Asphyxia 



933 



This agrees with what our former studies taught us. The 

 greater absorption of the exterior oxygen at the beginning results 

 in a relative persistence of the oxygen content of the arterial 

 blood. 



If now we construct a graph (Fig. 81), taking for the abscissae 

 the quantities of oxygen contained in the outer air at the various 

 moments of asphyxia, and plotting on the ordinates the quantities 

 of oxygen contained in 100 volumes of arterial blood, we reach a 

 result which is absolutely like line Ox (dotted line) of Figure 39, 

 furnished by asphyxia without carbonic acid. The carbonic acid 

 then seems to have had no effect. 



Fig. 81 — Relation between the oxygen content of the air and that of the 

 blood. 



And as to the carbonic acid, its proportion at first increases in 

 the blood, as we might have expected, since it increases in the air 

 which the animal breathes. But suddenly it decreases, and the 

 curve (Fig. 80) presents a point of retrogression corresponding to 

 1 hour 20 minutes; and so, in the last moments of life, there is in 

 the blood less C0 2 than there was a few instants before. When I 

 observed this fact for the first time, I thought that acid had been 

 absorbed by the tissues at the moment when the heart beats very 

 slowly. But if we, compare the line of the CCX of the blood (Fig. 

 79) with that of the C0 2 + (X of the air (Fig. 80) , we see a similar 

 point of retrogression which shows that, at the precise moment 



