FABRE'S BOOK OF INSECTS 



that is oxidised, and the air is supplied by the tube con- 

 nected with the Glow-worm's breathing-organs. But 

 as to the nature of the shining substance, no one as yet 

 knows anything. 



\Vc are better informed as regards another question. 

 We know that the Glow-worm has complete control of 

 the light he carries. He can turn it up or down, or 

 out, as he pleases. 



If the flow of air through the tube be increased, the 

 light becomes more intense: if the same air-tube, in- 

 fluenced by the will of the animal, stops the passage of 

 air, the light grows fainter or even goes out. 



Excitement produces an effect upon the air-tube. I 

 am speaking now of the modest fairy-lamp, the spots 

 on the last segment of the Glow-worm's body. These 

 are suddenly and almost completely put out by any kind 

 of flurry. When I am hunting for young Glow-worms 

 I can plainly see them glimmering on the blades of grass; 

 but should the least false step disturb a neighbouring 

 twig, the light goes out at once and the insect becomes 

 invisible. 



The gorgeous belts of the females, however, are very 

 little, if at all, affected by even the most violent sur- 

 prise. I fire a gun, for instance, beside a wire-gauze 

 cage in which I am rearing a menagerie of female Glow- 

 worms in the open air. The explosion produces no 



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