188 THE PHENOMENA OF MOTION 



the parts or constituents of the living tissue oppose to 

 a change in their form and composition, from the action 

 of new external active causes of change ; just as the 

 force of cohesion or of affinity is in direct proportion to 

 the resistance which these forces oppose to any external 

 cause, mechanical or chemical, tending to separate the 

 molecules, or the elements of an existing compound. 



The manifestations of the vital force are dependent 

 on a certain form of the tissue in which it resides, as 

 well as on a fixed composition in the substance of the 

 living tissue. 



The capacity of growth in a living tissue is deter- 

 mined by the immediate contact with matters adapted 

 to a certain decomposition, or the elements of which 

 are capable of becoming component parts of the tissue 

 in which vitality resides. 



The phenomenon of growth, or increase in the mass, 

 presupposes that the acting vital force is more powerful 

 than the resistance which the chemical force opposes to 

 the decomposition or transformation of the elements of 

 the food. 



The manifestations of the vital force are dependent 

 on a certain temperature. Neither in a plant nor in an 

 animal do vital phenomena occur when the temperature 

 is lowered to a certain extent. 



The phenomena of vitality in a living organism di- 

 minish in intensity when heat is abstracted, provided the 

 lost heat be not restored by other causes. 



Deprivation of food soon puts a stop to all manifes- 

 tations of vitality. 



