INFLUENCE OF FOOD. 



717 



equally under ordinary conditions, so that the respiratory quotient 

 remains practically unaltered. It is only immediately after work that 

 the respiratory quotient increases, and becomes sometimes greater than 

 unity. The absorption of oxygen needed for the work of walking on 

 level ground is, per kilo, body weight and minute, 0'1682 c.c. 

 maximum, and 0'0858 c.c. minimum ; for each kilogrammetre of work 

 performed in climbing, T5036 c.c. maximum, and 1*1871 minimum; and 

 similarly, for turning the wheel, 1*957 c.c. 



Lowy l shows that there is no definite value which can be assigned to 

 the increase of the respiratory exchange for the performance of a given 

 quantity of work under all circumstances, for the metabolism depends 

 upon the activity of the muscle, which varies under different conditions. 

 Active muscle working under favourable conditions performs its work 

 economically ; fatigued muscle working under unfavourable conditions 

 is the seat of an extravagant metabolism. 2 



The decrease observed in the respiratory exchange of animals under 

 the influence of chloroform, ether, chloral, and curari, is to be attributed 

 chiefly to the great decrease in the activity of the muscles. 3 



The influence of food upon the respiratory exchange. The effect 

 of a meal upon the respiratory exchange is to cause a marked increase 

 in the intake of oxygen and the output of carbon dioxide ; this is due 



1 Arch. f. d. ges. Physiol., Bonn, 1891, Bd. xlix. S. 405. See also, Gruber, Ztschr. f. 

 Biol., Milne-hen, 1891, Bd. xxviii. S. 466. 



2 ]? or further experiments upon the influence of work upon the respiratory exchange of 

 (a) man, see Hanriot and Richet, Ann. d. chim. et pJiys., Paris, 1891, Ser. 6, tome 

 xxii. p. 495 ; and Trav. du lab. de Ch. Richet, 1894, tome 1 ; (b) animals, Grandis, Arch, 

 ital. de biol., Turin, 1889, tome xii. p. 237 ; Smith, Journ. Physiol., Cambridge and 

 London, 1890, vol. xi. p. 65. Criticism of the same byZuntz and Lehmann, ibid., p. 396 ; 

 Grehant, Compt. rend. Soc. de biol., Paris, 1891, p. 14. 



3 Zuntz, Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 522 ; Pniiger, ibid., 1878, 

 Bd. xviii. S. 247; Rumpf, ibid., 1884, Bd. xxxiii. S. 538 ; Saint Martin, Compt. rend. 

 Acad. d. sc., Paris, 1887, tome cv. p. 1126 ; Richet, ibid., 1889, tome cix. p. 190 ; Arch. 

 de physiol. norm, etpath., Paris, 1890, tome ii. p. 221 ; Pembrey, " Proc. Physiol. Soc.," 

 Journ. Physiol., Cambridge and London, 1894-95, vol. xvii. 



