7 i6 



CHEMISTR Y OF RESPIRATION. 



E. Smith. 1 He found that a man produced 161/6 c.c. of carbon dioxide per 

 minute when he was perfectly at rest, as in a deep sleep ; that during a 

 walk at the rate of two miles (3048 metres) an hour, the discharge of 

 carbon dioxide was increased to 569'5 c.c., and to 851/2 c.c. when the 

 rate of walking was quickened to three miles (45 71 '9 metres) an hour. 

 The greatest increase, ' 1581 '9 c.c. of carbon dioxide per minute, was 

 caused by work upon a treadmill. 



In 1866, Pettenkofer and Voit 2 performed a series of important 

 observations upon the metabolism of healthy men, under different con- 

 ditions as regards work and diet, and they found that if unity represent 

 the value of the output of carbon dioxide and the intake of oxygen 

 when the man is at rest, then \^ork brings about the following 

 results : 



Carbon dioxide 

 Oxygen . 



During Hunger, 



O Q 

 ^ O 



2-1 



Moderate Diet. 

 1-6 

 1-8 



The numerous experiments made by Speck, 3 under different con- 

 ditions as regards the amount and nature of the work performed, show 

 that the air inspired, the oxygen absorbed, and the carbon dioxide 

 discharged, are greatly increased; the percentage composition of the 

 expired air is but little altered, and the respiratory quotient increases 

 slightly during the work. Hanriot and Richet 4 find for each kilo- 

 grammetre of work performed by a man, an increase of 3168 c.c. in the 

 oxygen absorbed, and 4*221 c.c. in the carbon dioxide discharged. 



In experiments upon horses, Zuntz and Lehmann 5 obtained the 

 following results : 



It is impossible here to discuss fully the quantitative relationship 

 between metabolism and work, but the conclusions reached by Katzen- 

 stein 6 are as follows : The work performed by the arms in turning a 

 wheel produces, per unit of work done, a greater increase in the respiratory 

 exchange than walking or climbing ; the absorption of oxygen is per unit 

 of work performed somewhat greater for light, than for heavy work ; 

 the absorption of oxygen and the discharge of carbon dioxide increase 



1 Phil. Trans., London, 1859, vol. cxlix..pt. 2, p. 681. 



2 Ztschr. f. BioL, Munchen, 1866, Bd. ii. S. 459. See also this article, p. 718, and 

 article by Voit in Hermann's "Handbuch," Bd. vi. Th. 1, S. 201. 



3 Deutsches Arch. f. klin. Med., Leipzig, 1889, Bd. xlv. S. 461. 



4 Oompt. rend. AcM. d. sc., Paris, 1887, tome civ. p. 1865 ; tome cv. p. .76. 



5 Landw. Jahrb., 1889, Bd. xviii. S. 1 ;,Journ. Physiol., Cambridge and London, 1890, 

 vol. xi. p. 396. , . 



6 Arch. f. d. ges. Physiol. , Bonn, 1891, Bd. xlix. S. 380. 



