THE GLOW-WORM 



only of two spots, which shine through the back, and are 

 visible both above and below the animal. From these 

 belts and spots there comes a glorious white light, deli- 

 cately tinged with blue. 



The male Glow-worm carries only the smaller of these 

 lamps, the two spots on the end segment, which are 

 possessed by the entire tribe. These luminous spots 

 appear upon the young grub, and continue throughout 

 life unchanged. And they are always visible both on 

 the upper and lower surface, whereas the two large belts 

 peculiar to the female shine only below the body. 



I have examined the shining belt under the micro- 

 scope. On the skin a sort of whitewash is spread, formed 

 of some very fine grain-like substance, which is the source 

 of the light. Close beside it is a curious air-tube, with 

 a short wide stem leading to a kind of bushy tuft of 

 delicate branches. These branches spread over the sheet 

 of shining matter, and sometimes dip into it. 



It is plain to me that the brightness is produced by 

 the breathing-organs of the Glow-worm. There are 

 certain substances which, when mixed with air, become 

 luminous or even burst into flame. Such substances are 

 called combustible, and the act of their producing light 

 or flame by mingling with the air is called oxidisation. 

 The lamp of the Glow-worm is the result of oxidisation. 

 The substance that looks like whitewash is the matter 



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