144 PHOSPHORIC INSECTS. 
gen and carbon, secreted by a particular gland, 
organized for that purpose. I believe this car- 
buret of hydrogen exists in the tissue of the 
Lampyride, where it forms, with other substances, 
that greasy matter that all observers have re- 
marked in the luminous tissue, not only of Lampy- 
ride, but of other phosphorescent insects. But I 
doubt that the phosphorescence of these insects 
is owed to combustion. However, I have given 
this opinion its due in the theoretical part of my 
work. 
M. Schnetzler* has brought forward some other 
observations on Lampyris noctiluca, which appear 
worthy of note. It is generally believed that the 
hight of the glowworm is not visible in the day- 
time, for the simple reason, perhaps, that a light 
sixty times stronger than another prevents our 
perceiving the latter. But, according to the au- 
thor just named, if the inferior posterior portion 
of the abdomen of a female glowworm be opened, 
we perceive a yellowish-white substance which 
emits a very feeble ight during the duy. 
Although the hght of the glowworm appears 
to be in direct submission to the will, or rather to 
the instinct of the insect during its life, and can 
therefore be extinguished more or less at certain 
intervals, it is not less true that this hght persists 
for some time after death, and even after the lum1- 
* Loe. cit. 
