IN THE ANIMAL ORGANISM. 237 



equal to the effects produced during 7 hours in the 

 shape of formation of new parts. 



An old man sleeps only 3| hours ; and if every thing 

 else be supposed the same as in the case of the adult, 

 he will be able, at all events, to produce half of the 

 mechanical effects produced by an adult of equal 

 weight; that is, he will be able to carry only 15 Ibs. 

 instead of 30 to the same distance. 



The infant at the breast sleeps 20 hours and wakes 

 only 4 ; the active force consumed in formation of 

 new parts is, in this case, to that consumed in mechani- 

 cal 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 mechanical effects a quantity 

 of force corresponding to the proportion available in 

 the adult, then the mechanical 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 Force expended in 



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 be- 

 tween 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 restoration of the equili- 



