168 PHOSPHORESCENCE. L.ECT. VIII. 



continued alive and emitted much light. Thus, then, when 

 the insect is placed in its natural conditions with regard to 

 temperature, humidity, &c., and continues to be nourished, 

 the phosphorescent matter is preserved independent of solar 

 action. 



We conclude, therefore, from the preceding experiments, 

 that the phosphorescent matter prepared by the animal, is 

 preserved for some time luminous, although the animal be 

 deprived of life; proving that life is not an indispensable 

 condition of phosphorescence. By life, this substance is 

 continually preserved with its properties entire, by the same 

 process of nutrition which operates equally upon all parts of 

 the animal. 



Agency of the Nervous System. I have not omitted to 

 examine, what part the nervous system takes in the produc- 

 tion of the phenomenon ; and I shall describe the experi- 

 ments, made for this purpose, with all the necessary 

 details. 



If, immediately after a glow-worm is caught, we place it 

 on its back, and examine it, we perceive that the posterior 

 abdominal segments are reddish green. During the day 

 this colour is not so distinct, and is yellowish ; and the same 

 thing occurs with glow-worms which have been dead a 

 short time. During the life of the insect, the segments be- 

 come, from time to time, luminous, and more or less fre- 

 quently. By attentive observation made on many insects, 

 it has been discovered that sometimes the light does not 

 appear at every part of the segments at the same time. If 

 we slightly irritate any part of the insect, the light becomes 

 for an instant visible. By touching one of the points of the 

 segments, the light continues longer. If, at this moment, 

 we cut off the head of the animal, the light soon diminishes, 

 afterwards entirely ceases, and then the red colour of the 

 membrane of the luminous segments is very perceptible. 



