188 PRINCIPLES OF ANIMAL NUTRITION. 
Chauveau & Kaufmann * have more recently obtained simi- 
lar results. Their experiments were made upon the Levator labii 
superioris of the horse, both in a state of rest and in a state of activ- 
ity consequent upon the consumption of food. From the amount 
and composition of blood entering and leaving this muscle the 
following results were obtained for the oxygen consumed and carbon 
dioxide given off per kilogram of muscle in one minute. On the 
average of the three experiments, in round numbers, twenty-one 
times as much oxygen was consumed during work as during rest and 
twenty-nine times as much carbon dioxide was given off. 
Oxygen Consumed. Carbon Dioxide Given Off. 
Experiment. : : 
Rest, Work. Work + Rest, Work. Work -+- 
Grms. Grms. Rest. Grms. Grms. Rest. 
ee acis. Piers dad east .00479 | .07148 14.9 .00365 | .12534 34.3 
Dic snhe she behede sao .01167 | .20190 17.3 .01168 | .35488 30.4 
ee ree .00419 | .14899 35.6 .00518 | .25709 49.6 
Average........] .00688 | .14079 20.5 .00864 | .24577 28.5 
These facts show plainly that the increased metabolism of the 
active muscle cannot consist wholly of a direct oxidation, since the 
carbon dioxide given off from the muscle contains more oxygen 
than direct experiment shows to have been taken up by the muscle 
during the same time. 
Oxycen not Essentiay.—A further and still more striking 
proof of the above assertion is found in the fact that the living 
muscle can execute a considerable number of contractions in the 
entire absence of oxygen. 
Setschenow is quoted by Ludwig & Schmidt ¢ as having found 
that muscles would contract freely when supplied with oxygen-free 
blood, while L. Hermann { has shown that an excised muscle may 
continue to contract ina vacuum. The well-known investigations 
of Pfliiger § show that frogs may continue to live and execute more 
or less extensive motions in an atmosphere of pure nitrogen for 
* Comptes rend., 104, 1126, 1352, 1409. 
t Verhandl. Sichs Akad. d. Wiss., Math-Phys, Klasse, 20, 12. 
} Unters. u. Stoffw. der Muskeln. 
§ Arch. ges. Physiol., 10, 313. 
