176 THE INDUCTIONS OF BIOLOGY. 



chemical compounds appropriated by trie organism under 

 the form of food. As much power as was required to raise 

 the elements of these complex atoms to their state of unsta- 

 ble equilibrium, is given out in their falls to a state of stable 

 equilibrium ; and having fallen to a state of stable equilib- 

 rium, they can give out no further power, but have to be 

 got rid of as inert and useless. It is an inevitable corollary 

 " from the persistence of force, that each portion of mechanical 

 or other energy which an organism exerts, implies the trans- 

 formation of as much organic matter as contained this 

 energy in a latent state;' 3 and that this organic matter in 

 yielding up its latent energy, loses its value for the purposes 

 of life, and becomes waste matter needing to be excreted. 

 The loss of these complex unstable substances must hence be 

 proportionate to the quantity of expended force. Here then 

 is the rationale of certain general facts lately indicated. 

 Plants do not waste to any considerable degree, for the obvi- 

 ous reason that the sensible and insensible motions they 

 generate are inconsiderable. Between the small waste, small 

 activity, and low temperature of the inferior animals, the rela- 

 tion is similarly one admitting of a priori establishment. Con- 

 versely, the rapid waste of energetic, hot-blooded animals 

 might be foreseen with equal certainty. And not less mani- 

 festly necessary is the variation in waste which, in the same 

 organism, attends the variation in the heat and mechanical 

 motion produced. 



Between the activity of a special part and the waste of 

 that part, a like relation may be deductively inferred ; though 

 it cannot be inferred that this relation is equally defi- 

 nite. Were the activity of every organ quite independent 

 of the activities of other organs, we might expect to trace 

 out this relation distinctly ; but since one part of the force 

 which any organ expends, is derived from materials brought 

 to it by the blood from moment to moment in quantities 

 varying with the demand, and since another part of the 

 force which such organ expends, comes to it in the shape of 



