THE GLOW-WORM 47 



dimmed, if I do not press too hard with my thumb. Nothing 

 short of very serious reasons would make the insect put out 

 its signals altogether. 



All things considered, there is not a doubt but that the 

 Glow-worm himself manages his lighting-apparatus, extin- 

 guishing and rekindling it at will ; but there is one circum- 

 stance over which the insect has no control. If I cut off a 

 strip of the skin, showing one of the luminous belts, and place 

 it in a glass tube, it will shine away merrily, though not quite 

 as brilliantly as on the living body. The presence of life is 

 unnecessary, because the luminous skin is in direct contact 

 with the air, and the flow of oxygen through the air-tube is 

 therefore not required. In aerated water the skin shines as 

 brightly as in the free air, but the light is extinguished in 

 water that has been deprived of its air by boiling. There 

 could be no better proof that the Glow-worm's light is the 

 effect of oxidisation. 



The light is white, calm, and soft to the eyes, and suggests 

 a spark dropped by the full moon. In spite of its splendour 

 it is very feeble. If we move a Glow-worm along a line of 

 print, in perfect darkness, we can easily make out the letters 

 one by one, and even words when they are not too long ; 

 but nothing is visible beyond this very narrow zone. A 

 lantern of this kind soon tires the reader's patience. 



These brilliant creatures know nothing at all of family 

 affection. They lay their eggs anywhere, or rather strew 

 them at random, either on the earth or on a blade of grass. 

 Then they pay no further attention to them. 



From start to finish the Glow-worm shines. Even the 

 eggs are luminous, and so are the grubs. At the approach 

 of cold weather the latter go down into the ground, but not 

 very far. If I dig them up I find them with their little stern- 

 lights still shining. Even below the soil they keep their lanterns 

 bravely alight. 



