IN THE ANIMAL ORGANISM. 233 



That which is expended, in mechanical effects, in 

 the shape of velocity, is lost in time ; that is to say, 

 the more rapid the motions are, the sooner or the more 

 quickly is the force exhausted. 



The sum of the mechanical force produced in a 

 given time is equal to the sum of force necessary, 

 during the same time, to produce the voluntary and 

 involuntary motions ; that is, all the force which the 

 heart, intestines, &c., require for their motions is lost 

 to the voluntary motions. 



The amount of azotized food necessary to restore 

 the equilibrium between waste and supply is directly 

 proportional to the amount of tissues metamorphosed. 



The amount of living matter, which in the body 

 loses the condition of life, is, in equal temperatures, 

 directly proportional to the mechanical effects produced 

 in a given time. 



The amount of tissue metamorphosed in a given time 

 may be measured by the quantity of nitrogen in the 

 urine. 



The sum of the mechanical effects produced in two 

 individuals, in the same temperature, is proportional to 

 the amount of nitrogen in their urine ; whether the me- 

 chanical force has been employed in voluntary or invol- 

 untary motions, whether it has been consumed by the 

 limbs or by the heart and other viscera. 



That condition of the body which is called health in- 

 cludes the conception of an equilibrium among all the 

 causes of waste and of supply ; and thus animal life is 

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