46 FABRE'S BOOK OF INSECTS 



air is called oxidisation. The lamp of the Glow-worm is the 

 result of oxidisation. The substance that looks like white- 

 wash is the matter that is oxidised, and the air is supplied by 

 the tube connected with the Glow-worm's breathing- organs. 

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

 knows anything. 



We 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, influenced 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 surprise. 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 result : the illumination con- 

 tinues, as bright and placid as before. I take a spray, and 

 rain down a slight shower of cold water upon the flock. Not 

 one of my animals puts out its light ; at the very most there 

 is a brief pause in the radiance, and then only in some cases. 

 I send a puff of smoke from my pipe into the cage. This time 

 the pause is more marked. There are even some lamps put 

 out, but they are soon relit. Calm returns, and the light is 

 as bright as ever. I take some of the captives an my fingers 

 and tease them a little. Yet the illumination is not much 



