HISTORICAL NOTES. 175 
act, by which these insects separated light from 
their food, and afterwards secreted it in a sensible 
form. When we recall the chemical theories in 
vogue at that period, we find that Brugnatelli’s 
opinion is not so ridiculous as one would be apt 
to suppose. 
Carradori, another Italian naturalist, appears 
to have admitted Brugnatelli’s opinion ; but know- 
ing that the Lampyride could extinguish or emit 
their hight at will, he thought that they effected 
this with a peculiar membrane acting as a screen, 
by which the insect (Lampyris italica) hid its 
hight. The existence of this membrane was after- 
wards denied by Macartney in the ‘ Philosophical 
Transactions for 1810.’ But Carradori caused 
science to take a step forward when he proved 
that the hght of Lampyris italica was not imme- 
diately extinguished im vacuo, in oil, or under 
water, as the hght of a candle, or that of common 
phosphorus would be. 
Boyle, Hume, and Macaire have all observed 
that the phosphorescence of certain dead organic 
matters was extinguished, at least partially, in 
vacuo. Boyle’s experiments on this subject were 
published in the ‘ Philosophical Transactions’ for 
1668. Although he certainly did happen once to 
extinguish the hght of phosphorescent wood, in 
vacuo, completely, he never succeeded in totally 
extinguishing that emitted by dead fish, 
