PHOSPHORIC INSECTS. 145 
nous substance has been extracted from the in- 
sect’s body. According to Carus,* the hght, when 
extinguished in the dry luminous matter, reap- 
pears when the latter is damped with water. he 
naturalist Boitard has made a similar assertion ; 
speaking of the glowworm’s light, he says: “ Il 
parait qwils peuvent 4 volonté augmenter ou 
diminuer cette singulitre lumicre, qui disparatt 
lorsqwils sont morts, mais seulement par le des- 
séchement.’+ 
We are thus led to infer that the luminous sub- 
stance of glowworms is permanently phosphores- 
cent even after death, if the tissue of the lumi- 
nous organ be kept dry, and not decomposed by 
chemical means. 
When the insect, dead or living, is plunged 
into boiling water, its light is extinguished sud- 
denly. A vigorous individual plunged into olive 
oil soon loses its brightness, but a feeble lumi- 
nosity persists for a long time even after death. 
The microscope shows us in the luminous sub- 
stance of glowworms a cellular tissue, filled with 
what appears to be a soft yellowish grease; the 
whole is traversed by the trunks and branches of 
the trachez or air-tubes. ‘T'his substance extends 
in a thin layer along the inner sides of the ab- 
domen. It is this greasy substance, this corps 
graisseue, that Treviranus regarded as the source 
* Comp. Anat. + ‘Manuel d’Entomologie.’ Paris, 1828. 
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