IN THE ANIMAL ORGANISM. 249 



of equal weight ; that is, he will be able to carry 

 only 15 lbs. instead of 30 to the same distance. 



The infant at the breast sleeps 20 hours and 

 wakes only four ; the active force consumed in forma- 

 tion of new parts is, in this case, to that consumed in 

 mechanical effects (in motion of the limbs), as 20 to 

 4 ; but his limbs possess no momentum of force, for 

 he cannot yet support his own body. If we assume, 

 that the aged man and infant consume in mechani- 

 cal effects a quantity of force corresponding to the 

 proportion available in the adult, then the mechani- 

 cal effects are proportional to the number of waking 

 hours, the formation of new parts to the number of 

 hours of sleep, and we shall have : 



Force expended in Force expended in 



mechanical effects. formation of new parts. 



In the adult 17 : 7 



In the infant 4 : 20 



In the old man 20 : 4 



In the adult, a perfect equilibrium takes place 

 between waste and supply ; in the old man and in 

 the infant, waste and supply are not in equilibrium. 

 If we make the consumption of force in the 17 

 waking hours equal to that required for the restora- 

 tion of the equilibrium during sleep == 100 = 17 

 waking hours, = 7 hours of sleep, we obtain the 

 following proportions. The mechanical effects are 

 to those in the shape of formation of new parts : 



In the adult man = 100 : 100 

 In the infant . . . = 25 : 250 

 In the old man... = 125 : 50 



