426 LUMINOUS INSECTS. 



ter, or increased by the application of heat ; that the 

 substance aifording- it, though poetically employed for 

 lighting the fairies' tapers'", is incapable of inflamma- 

 tion 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 precedi/ig hypotheses as unsatisfactory, but without 

 substitnting any other explanation ; suggesting, how- 

 ever, 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 be- 

 fore final decision can be pronounced. The different 



' " And for night-tapers crop their waxen thighs, 

 And light them at li)e 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 receptacles 

 being extracted with a penknife continut-d luminous; but on being im- 

 mersed 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 re- 

 ceptacle continued luminous forfive minutes, the light gradually disappear- 

 ing. — 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 luminous property, and become dry and glossy 

 like gum, in about t .^ o minutes, but recovered it again on being moistened 

 with saliva, and again lost it when dried When the matter was ex- 

 tracted from two or three glow-worms, and covered with liquid gum- 

 arabic, it continued luminous for upwards of a quarter of an hour. 



