ON LUMINOWS ANIMALS. 47 



The phenomenon of animal light has been attempted to Theories of 

 , 1 • 1 . T«' T> •* animal light. 



be explained in difterent ways. 15y many persons it was 



formerly ascribed to a putrefactive process; but, jsince the 

 modern theories of combustion became known, it has been 

 generally believed to depend upon an actual inflammation 

 of the lumous substance, similar to the slow combustion of 

 phosphorus. Others have accounted for the luminous ef- 

 fect, by supposing the matter of light to be accumulated, 

 and rendered latent under particular circumstances, and 

 afterward evolved in a sensible form. 



The opinion of the light of living animals being the con- It cannot b« 

 sequence of putrefaction is evidently absurd, and contra- "^'"^.^^l*"" 

 dictory to all observatioip 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 oniy 

 during the first stages of the dissolution of the body, and 

 that no light is emitted after putrefaction has really com- 

 menced. 



Spallanzani, who was the most strenuous advocate for the Arguments for 

 phosphorescent nature of animal light, stated, that glow- phores"cent'br 

 worms shone more brilliantly when put into oxigen gas ; Spallanzani 

 that their light gradually disappeared in hidrogen 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 temperature. He conjectured, that the luminous 

 matter of these insects was composed of hidrogen and car- 

 bonated hidrogen gas. 



Forster relates, in the Lichtenberg Magazine for 1783, and Forstcr. 

 that, on putting a lampyris splendiduia into oxigen gas, it 

 gave as much light as four of the same species in common 

 air. 



Carradori has made some experiments upon the lucciole, Arguments 

 (lampyris italica) which led him to deny its phosphores- ^p'"^' " **y 

 cence. He found, that the luminous portion of the belly 

 of the insect shone in vacuum, in oil, in water, and different 

 liquids, and under different circumstances, where it was ex- 

 cluded from all communication with oxigen gas. He ac- 

 counts for the result of Forster's experiment, by supposing, 

 that the worm shone more vividly, because it was more ani- 

 mated in oxigen gas than in commop air. 



Carradorj 



