97 



LECTUEE V. 



Muscular action dependent on muscular metamorphosis Theoretic oxidation 

 of muscle into one proportion of urea and seven of carbonic acid Prac- 

 tical results Dynamic value of muscle oxidation Quantities of heat 

 producible by combustion of hydrogen and carbon Difference between 

 quantity and intensity of heat Unit of heat equivalent to 424 kilo- 

 'grammetres of motion Quantities of motion producible by combustion 

 of hydrogen and carbon Economy of muscle as a motive exponent of 

 combustion Reciprocity of heat and motion in muscular action Solar 

 origin of muscular force Amount of force derivable from muscle pro- 

 portional to degree of its oxidation Imperfect knowledge of natural 

 process of oxidation Artificial oxidation of muscle Nature of inter- 

 mediate products Relation of aldehydes and nitriles to acids Simple 

 constitution of acids obtained by muscle oxidation Production of both 

 fatty and aromatic compounds General distribution of leucine and tyro- 

 sine Their formation by indirect oxidation of nitrogenous tissue 

 Leucine the most elaborate of fatty, and tyrosine of aromatic animal 

 products Constitution and analogies of leucine or amido-caproic acid 

 Probable constitution of tyrosine, or ethylamido-salicic acid Natural 

 history of salicic compounds, including indigo Occurrence in human 

 urine of indigo, salisuric acid, and phenol Relationship of tyrosine to 

 hippuric acid. 



(103.) THAT muscular exertion is dependent on muscular me- 

 tamorphosis or oxidation is a subject rather for the physiologist 

 than the chemist to dilate upon. Perhaps, however, I may be 

 permitted to remind you of such observations as the following 

 that a free supply of thoroughly oxygenated arterial blood is 

 essential for complete well-developed muscular action ; that the 

 volume of oxygen contained in blood which has circulated 

 through a contracting muscle is less than one-fourth of that con- 

 tained in blood which has traversed the same muscle at rest, 



H 



