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 

 Lampyridte, where it forms, with other substances, 

 that greasy matter that all observers have re- 

 marked in the luminous tissue, not only of Lampy- 

 rida, 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 

 light 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 light during the day. 



Although the light 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 light persists 

 for some time after death, and even after the lumi- 



* Loc. cit. 



