V7 PHOSPHORESCENCE. 
Glow-worm, and LAMPYRIS SPLENDIDULA, in both of which the females 
are slightly larger and are wingless. The male of L. sPpLeENDIDULA 
has large wings and elytra, and flies swiftly. It is concealed by day 
in trunks of trees, etc. The male of L. NocriLuca is comparatively 
sluggish and keeps amongst the grass. The finer and more sustained 
display of light is made by the female, though the males are able to 
emit a certain amount of light—generally in a rhythmic way and 
often in short flashes. In a few species—the American PHortinus 
DIMLssUS is one—only the male is luminous. The luminous organs 
occupy the underpart of the three last segments of the abdomen, 
being generally of a yellowish hue. They consist of fatty-looking 
cells interspersed with clear cells of a cylindrical form ; around the 
structures there appears to bea plentiful supply of trachez, whose 
function may be to afford a liberal supply of oxygen. Schulze says 
that a pale transparent superficial layer gives off the light anda 
dense opaque layer possibly serves as a reflector. (ne of the chief 
objects of the light is undoubtedly to serve as a signal between the 
sexes. Darwin considered Mr, Belt’s suggestion to be correct, that 
the light of the Glow-worm is also a signal to its enemies of its being 
of an unpalatable character. Even the eggs of Lampyris shew 
some luminosity as do the pup and larve. 
A good many experiments and observations have been made on 
the character of the light emitted, but so far as I am aware nothing 
much has been done of late in conjunction with the newer aids to 
research which are at command. I will refer briefly to what is on 
record about the light of the Glow-worm :— 
“The light is stimulated by warm water and depressed by cold. 
The light has been emitted in vacuo and in inert gases (LATREILLE). 
It is affirmed that the Glow-worm has been known to detonate in 
hydrogen gas. Panceri says that an air supply is necessary, that 
oxygen intensifies the light, and that an atmosphere of carbonic acid 
extinguishes it. He thinks that a fat containing free phosphorus. 
