The Story-Book of the Fields 



felt incessantly, always imperious and in- 

 exorable. 



Let us try for a moment to prevent the air 

 from entering our body by closing its passage 

 through the nose and mouth. It is impossible 

 to endure it, we are stifled and feel that we 

 should certainly perish if this condition were 

 at all prolonged. This will convince us of 

 the necessity of air for life. All animals 

 from the least to the greatest are in the same 

 case ; above all, they live on air. Those that 

 live in water — fishes and others — are no 

 exception to the rule. They can only live 

 in water into which air passes and is dissolved. 



In physics we have a striking experiment 

 with regard to this subject. An animal — 

 a bird, for instance — is placed under a bell 

 glass, and then the air is withdrawn by means 

 of a special pump called an air pump. As the 

 air disappears, being drawn out by the pump, 

 the bird totters, struggles in terrible distress 

 and falls down in a dying condition. If we 

 are slow in restoring the air to the bell the 

 poor little thing will certainly die : nothing 

 can restore it to life. But if the air is restored 

 in time its action will revive the bird. In 

 the same way a lighted candle placed under 

 the bell will be at once extinguished if the air 



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