90 



PHOSPHORESCENCE IN 



bottom and on the walls of dark damp mines or 

 moist caverns, on old decayed humid towers, etc.* 

 evolve a tranquil phosphoric light, which some- 

 times attracts attention by its intensity. 



The phosphorescence of R. sulterranea is fre- 

 quent in coal mines, and has been many times 

 observed near Dresden. Counsellor Ehrman has 

 spoken with enthusiasm of its pleasing effect in 

 these lone and desolate places. Having once de- 

 scended into one of the Swedish mines, he saw 

 these "vegetable glowworms" gleaming along its 

 walls or shining in some obscure recess. 



Caverns in the granitic rocks of Bohemia are 

 often beautifully decked with this luminous cryp- 

 togam, and I am told that our English coal-mines 

 occasionally exhibit, by its aid, a light sufficiently 

 clear to admit of reading ordinary print. 



