644 ANNUAL REGISTER, 1810. 



gave light nor communicated any 

 luminous appearance to water. 



Spallanzani discovered a raucous 

 luminous fluid in the plumule of 

 the pennatula phosphorea. 



The phaenomenon of animal 

 lighthas been attempted to be ex- 

 plained in different ways. By 

 many persons it was formerly as- 

 cribed to a putrefactive process : 

 but since the modern theories of 

 combustion became known, it has 

 been generally believed to depend 

 upon an actual inflammation of 

 the luminous substance, similar to 

 the slow combustion of phospho- 

 rus. Others have accounted for 

 the luminous effect by supposing 

 the matter of light to be accumu- 

 lated, and rendered latent under 

 particular circumstances, and af- 

 terwards evolved in a sensible 

 form. 



The opinion of the light of liv- 

 ing animals being theconsequence 

 of putrefaction, is evidently ab- 

 surd, and contradictory to all ob- 

 servation on the subject. It has 

 been proved by the experiments of 

 Dr. Hulme and others, that even 

 the luminous appearances of dead 

 animals are exhibited only during 

 the first stages of the dissolution 

 of the body, and that no light is 

 emitted after putrefaction has 

 already commenced. 



Spallanzani, who was the most 

 strenuous advocate for the phos- 

 phorescent nature of animal light, 

 stated that glow-worms shone 

 more brilliantly when put into 

 oxygen gas ; that their light gra- 

 dually disappeared in hydrogen, 

 or in azotic gas, and was instantly 

 extinguished in fixed air ; that it 

 was also lost by cold, and revived 

 by the application of a warm tem- 

 perature. He conjectured that the 



luminous matter of these insects 

 was composed of hydrogen and 

 carbonated hydrogen gas. 



Forster relates, in the Lichten- 

 berg Magazine for 1783, that on 

 putting a lampyris splendidula 

 into oxygen gas, it gave as much 

 light as four of the same species in 

 common air. 



Carradori has made some expe- 

 riments upon thelucciole (lampy- 

 ris italica) which led him to deny 

 its phosphorescence. He found 

 that the luminous portion of the 

 belly of the insect shone in va- 

 cuum, in oil, in water, and dif- 

 ferent liquids ; and under different 

 circumstances, where it was ex- 

 cluded from all communication 

 with oxygen gas. He accounts 

 for the result of Forster's experi- 

 ment, by supposing that the worm 

 shone more vividly, because it was 

 more animated in oxygen gas than 

 in common air. 



Carradori adopts on this subject 

 the doctrine of Brugnatelli, and 

 ascribes the luminous appearances 

 of animals to the condensation and 

 extrication of light in particular 

 organs, which had previously ex- 

 isted in combination with the 

 substance of their bodies. He 

 supposes the light to be originally 

 derived from the food, or the at- 

 mospheric air taken into the body; 

 in short, that certain animals have 

 the peculiar property of gradually 

 imbibing light from foreign bo- 

 dies, and of afterwards secreting 

 it in a sensible form. 



The following experiments 

 which I made upon this subject, 

 would lead me to make different 

 conclusions than those of the pre- 

 ceding authors. 



Experiment 1. — A glow-worm 

 was put into a glass of water, in 



