198 THE PHENOMENA OF MOTION 



not only an unequal capacity for growth in the 

 mass, and an unequal power of overcoming che- 

 mical resistance, but also an inequality in the 

 amount of that resistance which the parts or con- 

 stituents 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 ex- 

 ternal cause, mechanical or chemical, tending to 

 separate the molecules, or the elements of an exist- 

 ing compound. 



The manifestations of the vital force are depen- 

 dent on a certain form of the tissue in which it re- 

 sides, as well as on a fixed composition in the sub- 

 stance of the living tissue. 



The capacity of growth in a living tissue is de- 

 termined 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 transforma- 

 tion of the elements of the food. 



The manifestations of the vital force are depen- 

 dent 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. 



