934 Experiments 



when COo diminishes in the blood, it increases considerably in the 

 expired air, that, in a word, it leaves the animal. In all my 

 analyses I have found this fact, unknown until now: a glance at 

 the summarizing tables is enough to convince anyone. 



We must not then continue to say, as was too easily admitted 

 a priori, that in asphyxia in closed vessels the quantity of CO, 

 contained in the blood keeps increasing until death; quite to the 

 contrary, it always diminishes in the last moments of life. 



Furthermore, when the volume of air in which the animal is 

 asphyxiated is small, the carbonic acid diminishes in the arterial 

 blood from the beginning, in spite of its increase in the air. This 

 is shown by Experiment DCXXXVII, for example, in which 

 although a large dog was given only 20 liters of air, the carbonic 

 acid content of its blood fell from 44.8 to 39.9. 



But when the carbonic acid is prevented from reaching the 

 outer air, as is the case with animals that are strangled or drowned, 

 it increases in the blood, but in a very small proportion. 



Examples: 



Experiment DCXLIII. April. Dog weighing 15.8 kilos. Drew 33 cc. 

 of arterial blood from the carotid .... A 



Placed a tube in the trachea, and immediately afterwards, a 

 stopper in the tube. Struggling, dead in 4 minutes. 



A cannula was inserted into the left heart; at the moment when 

 the heart stopped, 33 cc. of very dark blood was drawn . . . . B 



A contains per 100, CO, 33.9. 



B contains per 100, CO, 40.8. 



This answers most decisively the question which we asked our- 

 selves at the beginning of this chapter: Does the carbonic acid 

 produced during asphyxia play any part in causing death? 



All that we had learned showed us already that its role in all 

 cases must be decidedly limited. In order that carbonic acid may 

 bring on death in dogs, its proportion in the air must be more 

 than 30%; now in the confined air in which the animal is asphyxi- 

 ated, it never rises above 17 to 18. On the other hand, the dis- 

 turbances of circulation, locomotion, calorification, etc., and the 

 variations of the oxygen of the air and the oxygen of the blood are 

 the same in the cases in which the carbonic acid was eliminated 

 from the confined air in which the animal is breathing (Chapter 

 III, Subchapter II) and in ordinary asphyxia. 



But the experiments which we have just reported show that 

 the increase of carbonic acid in the arterial blood of asphyxiated 

 animals, when it exists, never reaches a figure much higher than 



