694 



CHEMISTRY OF RESPIRA TION. 



in the lungs, but in earlier works he had admitted that it might be in the 

 other organs of the body. 1 



It is now known that the essential seat of respiration is in the tissues and 

 not in the blood. The demonstration of this fact is chiefly due to the work of 

 Pfliiger and his pupils. 



EESPIRATOEY CHANGES IN AIR. 



Methods for the measurement of respiratory exchange. The 



simplest and at the same time the earliest method for the measurement 

 of respiratory exchange, is the analysis of the air of a bell jar, before 

 and after an animal has been confined in it. Such a method was used 

 by Black, 2 Priestley, 3 Lavoisier and Laglace, 4 and others. 5 The obvious 

 objection to this method is that the products of respiratory exchange 



FlG. 62. Regnault and Reiset's respiration apparatus. 



accumulate, while the oxygen diminishes, two conditions either of which 

 disturbs the normal respiratory exchange, and in time causes the death 

 of the animal. 6 Two modifications were introduced by Lavoisier to 

 remove these defects : in the one, the carbon dioxide was removed as it 

 accumulated, and a fresh supply of oxygen was added ; in the other, a 

 constant stream of fresh air was passed through the respiration chamber. 

 Upon the first of these principles, Eegnault and Eeiset 7 constructed the 

 apparatus with which they made numerous and important experiments 

 upon respiratory exchange. The above figure shows its construction. 



1 " (Euvres," 1862, p. 180. 2 "Lectures on Chemistry," ed. Robison, Edinburgh, 1803. 



3 Phil. Trans., London, 1772, vol. Ixii. pp. 147, 168. 



4 Hist. Acad. roy. d. sc., Paris, 1780, p. 355. ; "(Euvres de Lavoisier," tome ii. p. 326. 



5 Berthollet, Journ. f. Chcm. Physik. u. Min., Berlin, 1808, Bd. v. S. 388 ; Legallois, 

 Journ. f. Chetn. u. Phys., Niirnberg, 1817, Bd. xx. S. 113 ; Valentin, "Die Emflusse der 

 Vaguslalmiung auf die Lungen und Hautausdiinstung, " Frankfurt a/M., 1857 ; Arch. f. 

 exper. Path. u. PharmakoL, Leipzig, 1876, Bd. v. S. 143. 



6 Bernard, "Le9ons sur les effets des substances toxiques," 1857, p. 130; Friedlander 

 and Herter, Ztschr. f. physiol. Chem., Strassburg, Bd. iii. S. 19 ; Stroganow, Arch. f. d. 

 ges. Physiol., Bonn, 1876, Bd. xii. S. 18. See also this article, p. 743. 



7 Ann. de chim. et phys., Paris, 1849, Ser. 3, tome xxvi. 



