CHAPTER IV. 



EVOLUTION AND MUTABILITY OF LIVING MATTER 

 AND BRUTE MATTER. 



Supposed immobility of brute bodies — Mobility and mutability 

 of the sidereal world. — § i. The movement of particles and 

 molecules in brute bodies — The internal movements of 

 brute bodies — Kinetic conception of molecular motion — 

 Reality of the motion of particles — Comparison of the 

 activity of particles with vital activity. — § 2. Brownian 

 movement — Its existence — Its character — Its independence 

 of the nature of the bodies and of the nature of the environ- 

 ment — Its indefinite duration — Its independence of external 

 conditions — The Brownian movement must be the first 

 stage of molecular motion. — § 3. Motion of particles — 

 Migration of material particles — Migration under the 

 action of weight ; of diffusion; of electrolysis; of mechanical 

 pressure. — § 4. Internal activity of alloys — Their structure — 

 Changes produced by deforming agencies — Slow return to 

 equilibrium— Residual effect — Effect of annealing; effect 

 of stretching — Nickel steel — Colour photography — Con- 

 clusion — Relations of the environment to the living or brute 

 matter. 



One of the most remarkable characteristics of a Hving 

 being is its evolution. It undergoes a continuous 

 change. It starts from something very small ; it 

 assumes a configuration and grows ; in most cases 

 it declines and disappears, having followed a course 

 which may be predicted — a sort of ideal trajectory. 



Supposed Immobility of Brute Bodies. — It may be 

 asked whether this evolution, this directed mobility, 



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