OF FUNCTION; OR, HOW WE ACT. 9 



we render vapour tense in the steam-engine, we 

 raise weights in the clock, we compress the atmo- 

 sphere in the air-gun; and having done this, we 

 know that there is a source of power within them 

 from which the desired actions will ensue. The 

 principle is the same in the animal functions : the 

 source of power in the body is the storing up 

 of force. 



But in what way is force stored up in the body ? 

 It is stored up by resistance to chemical affinity. 

 It is a common observation, that life seems to 

 suspend or alter the chemical laws and ordinary 

 properties of bodies; and in one sense this is true? 

 though false in another. Life does not suspend the 

 chemical or any other laws ; they are operative still, 

 and evidence of their action is everywhere to be 

 met with ; but in living structures force is employed 

 in opposing chemical affinity, so that the chemical 

 changes which go on in them take place under 

 peculiar conditions, and manifest, accordingly, pecu- 

 liar characteristics. If I lift a heavy body, I employ 

 my muscular force in opposing gravity, but the 

 law of gravity is neither suspended nor altered 



