744 



CHEMISTR Y OF RESPIRA TION. 



Before any conclusions are drawn from the results given in the 

 foregoing table, it will be advisable to consider the cause or causes of 

 death in these cases of asphyxia. Do the animals die from a want of 

 oxygen, or are they poisoned by the accumulation of carbon dioxide ? 

 In order to answer this question, experiments have been made on the 

 duration of life of animals confined in air containing an excess of 

 oxygen, or an excess of both oxygen and carbon dioxide. Many 

 observations have been made by various physiologists, but the most 

 complete are those of Paul Bert. 1 The following table gives some of 

 his results : 



An Atmosphere containing an Excess of Oxygen. 



A consideration, of the following results leads to the conclusion, held 

 by Mayow 2 as early as 1674, that a warm-blooded animal confined in a 

 limited quantity of air dies from the want of oxygen, and this con- 

 clusion is supported by the fact that its blood is markedly venous 

 and contains little or no oxygen. The percentages of oxygen and of 

 carbon dioxide in the air at the time of death are about 3 and 

 15 respectively. On the other hand, when there is in the air an 

 abnormal excess of oxygen, and at the same time a great augmenta- 

 tion of carbon dioxide, the warm-blooded animal dies from poisoning 

 with carbon dioxide, and here again the conclusion is strengthened by 



Martigny, Arch. gtn. de mdd., Paris, 1827, tome xiv. p. 203 ; Snow, Edin. Med. 

 Journ., 1846, vol. Ixv. p. 49; Claude Bernard, "Lecons sur les effets des substances 

 toxiques et me'dicamenteuses," Paris, 1857 ; W. Miiller, Ann. d. Chem. u. Pharm., 1858, 

 Bd. cviii. S. 257 ; Valentin, Ztschr. f. rat. Med., 1861, Bd. x. S. 33 ; Beau, Arch. gen. de 

 med., Paris, 1860, Ser. 5, tome xvi. p. 64 ; 1864, Ser. 6, tome iii. p. 1 ; Paul Bert, 

 "Lemons sur la physiol. comp. de la respiration," Paris, 1870, p. 510. 



1 " Le9ons sur la physiol. comp. de la respiration," Paris, 1870, p. 518. 



- " Tractatus quinque," Oxonii, 1674. See also this article, p. 741. 



