INFLUENCE OF MUSCULAR EXERTION UPON METABOLISM. 219 
such a subject, little change is noted at first in the respiratory quo- 
tient. The cells of the body being richly supplied with carbohy- 
drates apparently utilize these as the most readily available source 
of energy. In either case, however, continued work makes large 
demands upon the non-nitrogenous materials available, the store 
of carbohydrates in the body is rapidly depleted, and the fat of the 
body is drawn upon to an increasing extent as a source of energy, 
the necessary result being a diminution in the respiratory quotient. 
In the experiments of Chauveau & Laulanié only the respira- 
tory quotients corresponding to the total metabolism are given, and 
consequently the changes in the character of the metabolism indi- 
cated above can only be traced qualitatively. In Zuntz & Hage- 
mann’s investigations the increments of the carbon dioxide and 
oxygen over the rest values are given, and from them the propor- 
tion of oxygen applied respectively to the oxidation of fat and of 
carbohydrates is computed. The following average results for the 
various forms of work show clearly that the ratio of fat to carbo- 
hydrates metabolized may vary through a very wide range. 
Oxygen per Minute 
applied to the Oxida- 
tion of 
Kind of Work. Periods. 
Fat, Carbohy- 
¢.c. drates, ¢.c. 
Walking nearly horizontal........... } 4.3638 | 2.9962 
iT3 
10.433 7.465 
up a slight grade. . 
P sas 8.665 15.215 
£8 “ “ steeper grade. . 
Draft, nearly horizontal.............. : L 8.882 | 12.992 
Walking with load, nearly horizontal.. €, 1,0 5.962 3.317 
“up a grade ed auadk wataae RR é,,0,0 8.525 14.892 
Trot, nearly horizontal............... a, @, jf, 0 7.852 | 14/201 
“<” with load, nearly horizontal..... €,t,0 12.718- | 16.023 
a e draft, horizontal........... -9,f,% 14.007 | 45 A 050 
Tun InteRMEpIARY Metrapouism.—As stated, the conclusions 
drawn from the respiratory quotient relate, strictly speaking, to 
the total effect of muscular exertion upon the store of matter in the 
body. The results of such experiments show that, as a consequence 
of a given amount of work, a certain quantity of fat and of carbo- 
hydrates has been oxidized somewhere in the organism. 
