64 ME. NEWPOET ON THE NATTJEAL HISTOEY 



I have found the light of the larva of Lampyris noctiluca to 

 proceed from two little lobes on the ventral surface of the twelfth 

 segment, which are the only parts that transmit light in this 

 larva. The light, when the larva is nearly full-grown and full-fed, 

 in good health, and placed in a warm atmosphere, is at times 

 almost as brilliant for a few seconds as that emitted by the perfect 

 insect. But it is of short duration, and its degree of intensity is 

 not sustained; besides which, it is of a greener colour, and is 

 given out only when the insect is in motion : even then the light 

 is emitted only in flashes or scintillations. This fact, however, is 

 of some interest with reference to the nature of the light itself, its 

 emission being hardly referable to a phosphorescent property of 

 secreted fluid, but more probably to discharges of vital force 

 through nervous function. 



In support of this view, it may be said, that when the young 

 larvae are violently shaken and driven against the sides of a box, 

 they emit their light more brilliantly; and that the full-grown 

 larva, under such circumstances, gives out its light for a short 

 time almost as brilliantly as the perfect insect. The larva seems, 

 like the perfect insect, to have some control over its light, or at 

 all events to become excited to emit it under certain circumstances. 

 Thus, I have noticed that when the larvae had been exposed for a 

 short time to artificial light, they did not shine, or but very feebly ; 

 but when the light was suddenly removed, they at first gave out 

 not a single gleam of light, though in four or five minutes after- 

 wards one or two began to shine ; and when they had remained 

 undisturbed in darkness from a quarter to half an hour, most of 

 them were shining. 



I have found that the larvae shine during the whole night when 

 undisturbed. I placed a collection of larvae which had fed vora- 

 ciously during the day, in a glass phial, which was placed on a table 

 by my bedside on a dark night; and being awake during the 

 greater part of the night, I observed them shining at twelve, at 

 one, at two, at three, at four, and even so late as at five o'clock, 

 but always far less brightly than the imago. The creature thus 

 appears to have some control over the emission of its light in a 

 state of rest, for I have seen them shining when undisturbed 

 during the whole of the night. On the other hand, when they have 

 been exposed to light, either artificial or that of the sun, it was 

 found, when the illuminating influence was suddenly removed, that 

 they had ceased to shine ; but after remaining in darkness for a 

 few minutes, they gave out their light again, and continued to do 



