ON THE SERRICORNES. 3G7 



phosphoric lights. This light, according to some authors, 

 does not depend on the influence of any external cause, but 

 solely on the will of the insect. 



The glow-worms are found in summer, after the setting of 

 the sun, in meadows, on the sides of roads, and near bushes. 

 In the countries where these insects are very common, during 

 the quiet nights in the fine season, the males flutter in the air, 

 which they seem to fill with sparkles of fire ; and the females, 

 which during the day remain concealed vmder the grass, dis- 

 cover themselves during the evening and night, by the 

 brilliant light which they shed. As long as these insects are 

 at liberty, their light is very regular ; but once in our power, 

 they shine very irregularly, or not at all. When they are 

 disturbed, they emit a frequent light. Being placed upon 

 their back, they shine almost without interruption, in making 

 continual efforts to turn themselves round. - 



The luminous matter of these insects has excited the 

 curiosity of many philosophers. It has been the object 

 of frequent experiments, which have furnished some very 

 interesting observations, which we shall here relate. Forster 

 having announced that the light of the glow-worms was so 

 strong, and so continuous in the oxygen gas, that one might 

 read by it with facility, M. Beckerheim, in verifying this fact, 

 discovered that these insects live a long time, in vacuo, and 

 in different gases, the nitrous acid, muriatic and sulphurous 

 excepted, in which they die in less than eleven minutes. 

 He has also ascertained the following particulars : — 

 That they have never diminished the goodness of the gases 

 in which they have lived, whatever length of time they 

 may have remained there : that, on the contrary, hydrogen 

 gas has become detonating, in consequence of the sojourn 

 of these animals in it ; and that many gases, tried before 

 and after, have appeared to be ameliorated from the same 

 cause. 



