228 THE PHENOMENA OF MOTION 



A living part cannot increase in volnme at the 

 same moment in which a portion of it loses the 

 vital condition, and is expelled from the organ in 

 the form of a lifeless compound ; on the contrary, 

 its volume must diminish. 



The continued application of the momentum of 

 force in living tissues to mechanical effects deter- 

 mines, therefore, a continued separation of matter ; 

 and only from the period at which the cause of 

 waste ceases to operate, can the capacity of growth 

 be manifested. 



Now, since, in different individuals, according to 

 the amount of force consumed in producing volun- 

 tary mechanical effects, unequal quantities of living 

 tissue are wasted, there must occur, in every indi- 

 vidual, unless the phenomena of motion are to cease 

 entirely, a condition in which all voluntary mo- 

 tions are completely checked, in which, therefore, 

 these occasion no waste. This condition is called 

 sleep. 



The growth of one part, which is not deprived of 

 its vital force, cannot be in the slightest degree 

 affected by the consumption of the vital force of 

 another part in producing motion. The one may 

 increase in volume, while the other diminishes ; and 

 the waste in one can neither increase nor diminish 

 the supply in the other. 



Now, since the consumption of force for the in- 

 voluntary motions continues in sleep, it is plain that 

 a waste of matter also continues in that state ; and 



