PHOSPHORIC INSECTS. 141 
assert without danger, that in gases which extin- 
guish combustion the luminous substance ex- 
tracted from glowworms shines for thirty or forty 
minutes. 
The same author next remarks, that in oxygen 
gas, the phosphorescence of the luminous sub- 
stance shines three times longer. Only three times. 
But this may be due to a difference of vitality 
in the different individual insects submitted to 
examination. Heat increases the hight of glow- 
worms ; too great a temperature destroys it. 
On the whole, the experiments of M. Matteucci, 
made with remarkable delicacy, can lead to no 
conclusion which tends to establish the nature of 
the phosphorescence of the Lampyride ; unless, 
indeed, this conclusion be that the phenomenon 
in question is not directly owing to combustion. 
With the exception of a single one, the same 
may be said of those undertaken by M. Roberts, 
and communicated to the ‘Annales des Sciences 
Naturelles’ in December, 1842. M. Roberts has, 
however, noted a fact similar to the observation 
of Mr. Macartney, regarding the luminous sub- 
stance of the Scolopendra. I shall give it in his 
own words :— 
“Tf a female Lampyris be divided into two 
transversal halves, the light spread around by the 
abdominal portion disappears in about half an 
hour. But by placing this same portion near a 
