224 From Matter to Man. 



the essence of feeding in effecting motion in any 

 organism or mechanism is simply to produce a 

 stimulus. In effect, one kind of motion (chemical 

 action) only evokes another kind of motion (loco- 

 motion) ; for energy cannot vanish, it only changes 

 from one mode of motion into another eternally. 



Further, the digestion of food or the combustion of 

 fuel involves consumption of food and fuel and the 

 expenditure of energy ; hence, in order to sustain the 

 " life " exhausted by the locomotive in moving itself 

 — practically the opposite of Spencer's definition of 

 life, the continuous adjustment of external to internal 

 relations — the machine requires constant feeding with 

 suitable fuel. In other words, a going locomotive 

 requires coal, water, and air, in motion, which yield 

 as the residuum of their spent energy, steam, smoke, 

 ashes, and motion. But in those changed conditions 

 the fuel is no longer fuel but cinders, material unfit 

 for locomotive use ; consequently, the real fuel supply 

 must be continuous, or else the engine's locomotive life, 

 so to speak, stops. 



We now ask, Has the animal a similar dual energy 

 and life ? One, its energy, associated with its material; 

 and the other, its life, associated with its mechanism ? 

 The answer is clearly affirmative. An animal is 

 composed of similar elementary matter to a loco- 

 motive, but, in addition to iron- — of which it possesses 

 little — it contains numerous other more unstable 

 elements — oxygen, hydrogen, carbon, nitrogen, etc. 

 These elements equally with iron exert motion as 



