268 PHYSIOLOGICAL CHEMISTRY. 



of proteid in other organs. But however this may be, the 

 modern view is, notwithstanding, that the exchange of proteid in 

 the muscle is not increased by activity. 



The investigations on the amount of fat in removed muscles 

 during activity and at rest have not led to any definite results. 

 The experiments of VOIT on a starving dog, and those of PETTE^- 

 KOFEB and VOIT on a man, offer strong proofs to show that an 

 increased decomposition of the fat takes place during activity. 



If the results from the investigations thus far made of the 

 chemical processes going on in the active and inactive muscle were 

 collected together, we should find the following characteristics for 

 the active muscle. The active muscle takes up more oxygen and 

 gives off more carbon dioxide than the inactive muscle; still the 

 elimination of carbon dioxide is increased considerably more than 

 the absorption of oxygen. In work a consumption of carbohydrates, 

 glycogen, and sugar takes place. A consumption of sugar seems 

 only to have been shown in muscle with blood circulation, while a 

 consumption of glycogen also has been observed in removed muscle. 

 Lactic acid is formed in activity, which is carried off by the blood 

 and taken up and consumed by the liver. Acid-alkali phosphates 

 also seem to be produced by work. In regard to the behavior of 

 fats in removed muscles nothing is known with certainty, though an 

 increase in the consumption of fat in the organism has been ob- 

 served during activity. An increase in the nitrogenized extractive 

 bodies of the creatin group seems also to occur. In regard to the 

 albuminous bodies the views are contradictory; but an increased 

 elimination of nitrogen as a direct consequence of muscular exer- 

 tion has thus far not been positively proved. 



In close connection with the above-mentioned facts we have the 

 question as to the origin of muscular activity so far as it has its 

 origin in chemical processes. In the past the generally-accepted 

 opinion was that of LIEBIG, that the source of muscular action con- 

 sisted of a metabolism of the albuminous bodies; to-day another 

 view prevails. PICK and WISLICENTJS climbed the Faulhorn and 

 calculated the amount of mechanical force expended in the attempt. 

 With this they compared the mechanical equivalent transformed in 

 the same time, from the proteids, calculated from the nitrogen 

 eliminated with the urine, and found that the work really performed 



