LETTER XXV. 



ON LUMINOUS INSECTS. 



boast of our candles, our wax-lights, and our 

 Argand lamps, and pity our fellow-men who, ignorant 

 of our methods of producing artificial light, are con- 

 demned to pass their nights in darkness. We regard 

 these inventions as the results of a great exertion of 

 human intellect^ and never conceive it possible that 

 other animals are able to avail themselves of modes of 

 illumination equally efficient ; and are furnished with the 

 means of guiding their nocturnal evolutions by actual 

 lights, similar in their effect to those which we make use 

 of. Yet many insects are thus provided. Some are 

 forced to content themselves with a single candle, not 

 more vivid than the rush-light which glimmers in the 

 peasant's cottage; others exhibit two or four, which cast 

 a stronger radiance ; and a few can display a lamp little 

 inferior in brilliancy to some of ours. Not that these 

 insects are actually possessed of candles and lamps. You 

 are aware that I am speaking figuratively. But Provi- 

 dence has supplied them with an effectual substitute 

 a luminous preparation or secretion, which has all the 

 adyantages of our lamps and candles without their in- 

 conveniences ; which gives light sufficient to direct their 



