NUMBER XIX 

 LIVING LIGHTS 



LIFE is a powerful kind of activity. We see 

 this activity in many forms in the power of 

 self -increase that is so characteristic of living 

 creatures, one Infusorian becoming a million in a 

 week ; in the power of transforming matter, the 

 green plant changing air, water, and salts into bread, 

 the animal changing the plant into flesh. We see 

 life's wonderful activity in the economical trans- 

 formations of energy, for a living creature, considered 

 as an engine, gives more return for the potential 

 energy supplied to it (the food or fuel) than any 

 engine of man's device ; in the capacity for storing 

 potential energy without much leakage, as in the 

 trees of the forest ; in the manif oldness of the energy- 

 transformations that are accomplished, for we find 

 one and the same creature doing work, giving off 

 heat, emitting light, and exhibiting electrical changes. 

 We get a glimpse of the wonder of vital activity in the 

 exquisite responsiveness of living creatures, for a 

 sundew tentacle will detect the presence of a minute 

 drop of ammonium carbonate added to a large jar 

 of water ; the sensitive plant moves in answer 



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