222 THE PHENOMENA OF MOTION 



By the power of the conductors, the nerves, to 

 propagate the momentum of force in a living part, 

 or the effect which the active vital force inherent in 

 the part produces on all the surrounding parts, in 

 all directions where the force, or rather its mo- 

 mentum of motion, is consumed without resistance 

 (for without motion no change of matter occurs, 

 and when motion has begun, there is no longer re- 

 sistance), an equilibrium is obviously established in 

 the living part, between the chemical forces and 

 the remaining vital force ; which equilibrium would 

 not have occurred had not vital force been expended 

 in producing mechanical motion. 



In this state, any external cause capable of ex- 

 erting an influence on the form, structure, and com- 

 position of the organ meets with no further re- 

 sistance. If oxygen were not conveyed to it, the 

 organ would maintain its condition, but without any 

 manifestation of vitality. It is only with the com- 

 mencement of chemical action that the change of 

 matter, that is, the separation of a part of the organ 

 in the form of lifeless compounds, begins. 



The change of matter, the manifestation of me- 

 chanical force, and the absorption of oxygen, are, in 

 the animal body, so closely connected with each 

 other, that we may consider the amount of motion, 

 and the quantity of living tissue transformed, as 

 proportional to the quantity of oxygen inspired and 

 consumed in a given time by the animal. For a 

 certain amount of motion, for a certain proportion 



