174 PHOSPHORESCENCE LECT. VIII. 



what are the physico-chemical conditions under the in- 

 fluence of which these infusoria become phosphorescent. 



Phosphorescence of Putrescent Fish. There can be no 

 doubt that fish, by putrefaction, become luminous ; and 

 from this circumstance may perhaps, in some cases, be pro- 

 duced the phosphorescence of the sea. The few experi- 

 ments which I have made, prove that in a vacuum, or in 

 carbonic acid, this phosphorescence ceases, but recom- 

 mences in the air. 



Phosphorescence of the Human Body. In the annals of 

 medicine, there exist well established facts of the appear- 

 ance of flames upon the bodies of persons affected with 

 certain diseases. 



Phosphorescent Perspiration. A phosphorescent perspi- 

 ration of the feet has been spoken of, and it is curious to 

 observe the analogy which exists between the odour of the 

 phosphorescent substance of the glow-worm and the sweat 

 of the feet. All these cases of phosphorescence remain 

 unexplained. 



Phosphorescence ofAnnelides and Ophiura. I cannot con- 

 clude this lecture without mentioning to you the important 

 observations recently made by Quatrefage, upon the phos- 

 phorescence of the Annelides and the Ophiura. This dis- 

 tinguished naturalist has observed with the microscope, that 

 the phosphorescence of these animals belongs to the mus- 

 cular fibre, is intermittent, and becomes more vivid when 

 the fibre is irritated ; and after repeated contractions, ceases 

 for a certain time, being reproduced if the animal be left to 

 repose. 



Here is a point of analogy that you ought not to lose sight 

 of. The life and the functions of muscles are accompanied 

 by the disengagement of heat and of light, and these func- 

 tions are immediately dependent on the nervous agent. It 



