136 PHOSPHORIC INSECTS. 
examine them in the daytime, these imsects, as 
every one knows, are not characterized by any 
extraordinary feature, nor do they astonish us by 
their beauty. 
Lampyris noctiluca (fig. 25) is the species most 
abundant in England, Belgium, Germany, and the 
north of France. We all know it well. We have 
all admired it silently shining on the fresh green 
sward of the country, and we all value this msect 
for the agreeable souvenirs which it calls forth as 
we contemplate its soft hght. ‘These httle shiming 
beings remind us of our younger days. They 
were shown to us in our early childhood, and we 
have been taught to look upon them as something 
mysterious. ‘Those sparks in the grass, what are 
they? Insects! But the light!” How often 
have we not heard such questions. Or this, again : 
«Tell me, then,—you, a philosopher,—what is it, 
definitely, that produces the hght of the glow- 
worm?” To which we can only reply, ‘‘ Those 
sparks in the grass have excited the inquisitive- 
