154 PHOSPHORESCENCE. I.ECT. VIII. 



LECTURE VIII. 



PHOSPHORESCENCE OF ORGANIZED BEINGS. 



ARGUMENT. General remarks. 



Phosphorescence of the Glow-woYm ; effects of heat and cold on it ; in- 

 fluence of carbonic acid, of hydrogen, of atmospheric air, of chlorine, 

 of oxygen, of mixed gases, of sulphuretted hydrogen, and of rarefied 

 air. General conclusions. Cause of the phosphorescence : is not de- 

 pendent on insolation; agency of the nervous system; influence of 

 poisons. Microscopic structure of the luminous organs. Chemical 

 nature of the phosphorescent substance. Conclusions as to the cause 

 of the phosphorescence. 



Phosphorescence of animalcules ; of putrescent fish ; of the human body ; 

 of the perspiration ; of the annelides and ophiura ; of plants. 



Phosphorescence of Living Beings. LIVING beings do 

 not produce heat merely, many of them give out light also. 

 Although the latter be not a general phenomenon proper to 

 all organized beings, yet the numerous cases of it known 

 are of the highest importance, and they show us a singular 

 faculty of the living organism. We shall see in this lec- 

 ture, in studying the best known cases of animal phospho- 

 rescence, that the phenomenon involves physico-chemical 

 theories, so far as the general mode of its production is 

 concerned; and that its exceptional character is one of 

 those mysterious singularities which nature seems to have 

 distributed amidst the immense variety of beings, almost 

 without any previous attention to the animals on which she 

 bestows them, as if merely for the purpose of constraining 

 us to admire with humility the power of her creative skill. 



