426 LUMINOUS INSECTS. 
plication of heat; that the substance affording it, though 
poetically employed for lighting the fairies’ tapers a, is 
incapable of inflammation if applied to the flame of a 
candle or red-hot iron; and when separated from the 
body exhibits no sensible heat on the thermometer’s being 
applied to it—rejects the preceding hypotheses as un- 
satisfactory, but without substituting any other explana- 
tion; suggesting, however, that the facts he observed 
are more favourable to the supposition of light being a 
quality of matter than a substance?. 
Which of these opinions is the more correct I do not 
pretend to decide. But though the experiments of Mr. 
Macartney seem fairly to bear him out in denying the 
existence of any ordinary combination of phosphorus in 
luminous insects, there exists a contradiction in many of 
the statements, which requires reconciling before final 
decision can be pronounced. The different results ob- 
tained by Forster and Spallanzani, who assert that glow- 
a“ And for night-tapers crop their waxen thighs, 
And light them at the fiery glow-worms’ eyes.” 
> Some experiments made by my friend the Rev. R. Sheppard on 
the glow-worm are worthy of being recorded.—One of the recepta- 
cles being extracted with a penknife continued luminous; but on 
being immersed in camphorated spirit of wine became immediately 
extinct. The animal, with one of its receptacles uninjured, being 
plunged into the same spirit, became apparently lifeless in less than 
a minute; but the receptacle continued luminous for five minutes, 
the light gradually disappearing.—Having extracted the luminous 
matter from the receptacles, in two days they were healed, and filled 
with luminous matter as before. He found this matter to lose its 
juminous property, and become dry and glossy like gum, in about 
two minutes; but it recovered it again on being moistened with 
saliva, and again lost it when dried. When the matter was extracted 
from two or three glow-worms, and covered with liquid gum-arabic, 
it continued luminous for upwards of a quarter of an hour. 
