918 Experiments 



In the 3rd hour, the blood gained 11.0 volumes of C0 2 

 In the 4th hour, the blood gained 5.0 volumes of C0 2 

 In the 5th hour, the blood gained 5.5 volumes of CO, 

 In the last 



50 minutes, the blood gained 13.2 volumes of C0 2 



And so, except during the last hour, the CQ 2 content of the 

 blood increased less and less quickly, whereas the animal was 

 being poisoned. And that is easily understood, since we have seen 

 that the absorption of oxygen was growing slower in the same 

 way, so that the production of carbonic acid in the tissues was less 

 and less active and its discharge into the blood less and less con- 

 siderable. 



But in the last hour the blood suddenly acquires a considerable 

 quantity of CCX (See Fig. 76, line CO-) . A glance at the lines P 

 and R of the same figure, which express the number of the heart- 

 beats and of the respirations, explains this singular fact perfectly; 

 at the moment, in fact, the heart slowed down considerably, and 

 the respiratory movements, reduced to 10 and 8 per minute, ceased 

 for an instant: the blood must have lost less C0 2 in passing through 

 the lungs and have gained more in passing through the tissues. 

 Furthermore, the oxygen of the blood was consumed on the spot 

 and must have furnished a certain quantity of carbonic acid. 



Since the carbonic acid content of the blood has as its cause 

 the increasing tension of this gas in the confined air which the 

 animal was breathing, it was interesting to determine the ratio 

 between these two variable values. This is easily done by com- 

 paring the lines C0 2 (which have the same coordinates) of the 

 two figures 75 and 76, which express the two columns C0 2 of the 

 bag and CO. of the blood in the table summarizing Experiment 

 DCXV. 



We thus find first that when the air of the bag contained 10 % 

 of C0 2 , 100 cc. of arterial blood contained 55 volumes of the same 

 gas, and we are led, by similar comparisons, to draw up the fol- 

 lowing table: 



With of C0 2 in the air, there was 40 of it in the blood. 



With 10 of CO., in the air, there was 55 of it in the blood. Dif- 

 ference 15. 



With 20 of CO L> in the air, there was 70 of it in the blood. Dif- 

 ference 15. 



With 30 of CO L , in the air, there was 82 of it in the blood. Dif- 

 ference 12. 



