PHOSPHORIC INSECTS. 143 
This experiment was witnessed by many emi- 
nent savants, among whom were MM. Bérard, 
Dujés, Dubrewil, Balard, and Moquin-Tandon. 
M. Schnetzler, of Vevey (Switzerland), made 
some experiments upon Lampyris noctiluea im 
1854. He attributes the ight of these insects to 
the combustion of phosphorus, which he thinks 
he has found in the greasy tissue which constitutes 
the luminous organ of the insect.* Phosphorus 
probably exists in the luminous tissue, but only 
in the state of phosphates. By heating this tissue 
with nitric acid until complete dissolution was 
obtained with destruction of the organic matter, 
M. Schnetzler procured a solution showing those 
chemical reactions which characterize phosphates. 
But that does not prove that phosphorus ina free 
state exists in this tissue. 
An English chemist, Mr. Thornton Herapath, 
asserts, on the other hand, that the most delicate 
analysis did not show the shghtest quantity of 
phosphorus (as phosphate) in the bodies of those 
insects. 
Here, then, we have one observer inferring the 
existence of free phosphorus after finding phos- 
phates, and another denying the existence of free 
phosphorus after seeking for phosphates only. 
Mr. Herapath thinks, in his turn, that the hght 
of the glowworm is due to a compound of hydro- 
* ‘Archives des Sciences Physiques de Genéve,’ Noy. 1855. 
