200 THE PHENOMENA OF MOTION 



festation of force in a living tissue, the elements of the 

 food are made to combine in a new order ; it is quite 

 certain that the momentum of force or of motion in the 

 vital force was more powerful than the chemical attrac- 

 tion existing between the elements of the food.* 



The chemical force which >kept the elements together 

 acted as a resistance, which was overcome by the ac- 

 tive vital force. 



Had both forces been equal, no kind of sensible 

 effect would have ensued. Had the chemical force 

 been the stronger, the living part would have undergone 

 a change. 



If we now suppose that a certain amount of vital 

 force must have been expended in bringing to an equi- 

 librium the chemical force, there must still remain an 

 excess of force, by which the decomposition was ef- 

 fected. This excess constitutes the momentum of 

 force in the living part, by means of which the change 

 was produced ; by means of this excess the part ac- 

 quires a permanent power of causing further decompo- 

 sitions, and of retaining its condition, form, and struc- 

 ture, in opposition to external agencies. 



We may imagine this excess to be removed, and 

 employed in some other form. This would not of it- 



* The hands of a man, who raises with a rope and simple pulley, 

 30 Ibs. to the height of 100 feet, pass over a space of 100 feet, while 

 his muscular energy furnishes the equilibrium to a pressure of 30 Ibs. 

 Were the force which the man could exert not greater than would 

 suffice to keep in equilibrium a pressure of 30 Ibs., he would be una- 

 ble to i-aise the weight to the height mentioned. 



