134 LIFE IN NATURE. 



The case is the same as when, in a chronometer, 

 part of the force of the unbending spring is employed 

 to bend a secondary one. 



But in another respect, also, nutrition may be seen 

 to be identical with function. The very same pro- 

 cess which is the function of one body, is the nutri- 

 tion of another. The vegetable world, in so far as it 

 serves for food, has for its " function," in the strictest 

 sense, the nutrition of the animal. This is the result 

 which it effects by its regulated decomposition. The 

 animal instinct provides the conditions under which 

 the function of the vegetable is performed. The 

 plant yields up its life to nourish the animal body, 

 as that body, so nourished, in its activity yields up its 

 life to impart force to the world around. 



And this is but an illustration of a law which has 

 its basis in the very nature of force itself. Every 

 giving off of force has for its necessary effect the 

 storing up of force in equal amount elsewhere. The 

 two halves of this process cannot be divided. And 

 whichever half of it we may be at any time regard- 

 ing whether the storing up of force (which answers 

 to nutrition), or the giving it off (which answers 



