A MOUNTAIN STREAM 167 



keeping* them fit for contraction, result in producing 

 heat, and just as changes in the electric organs of 

 certain fishes, such as the Torpedo of the Mediter- 

 ranean, result in giving electric shocks, so chemical 

 changes in the Glow Worm's tail result in flashes of 

 light at the rate of over one a second. Man has 

 invented no lamp that can compare with the lumin- 

 escence of the Glow Worms and Fire Flies, for very, 

 very little of the energy of the insect's organ is wasted 

 in producing heat. It is almost all what may be called 

 " cold light," and it might be taken as an emblem of 

 the light of science, which as such has no warmth of 

 feeling in it ! It may be noted that there is no phos- 

 phorus in the substance which gives out light in the 

 Glow Worm, so that the word "phosphorescence" 

 should not be used in this connection. 



There is much that is still uncertain in regard to the 

 " Glow Worm golden in a dell of dew," but we know 

 that the big-eyed males gather to the female's lamp, 

 and that she shines more brightly when they come 

 near. Other living lights may serve other purposes, 

 but those of Glow Worms are surely love signals. 

 When mating is over the female crawls into the wood 

 and prepares for maternity. It has been noted that 

 the young Glow Worms would be useful in gardens, 

 for they are very fond of small slugs. What the full- 

 grown beetles eat, if they eat at all, is uncertain. 



On the outskirts of the pine forest into which the 

 mother Glow Worms retreat, there are enormous Ant 

 hills, fully three feet high and six feet in circum- 

 ference. They are the largest we have ever seen. 

 They are built mainly of the withered twin needles of 

 the Scots Pine, with fibres and small twigs and some 



