CRYPTOGAMIC PLANTS. 93 



and ceases to shine as soon as the sun rises. 

 The same author says that he never saw the 

 Agaricus olearius shine during the daytime, how- 

 ever dark the room in which it was kept ; and we 

 might remark upon this that fungi only vegetate 

 at night. But M. Fabre has, more recently, ob- 

 served that the phosphorescence of this agaric is 

 not intermittent, as M. Delille supposes, and that 

 it shines during the day as well as by night. Ex- 

 posure of the plant to sunlight appears to have no 

 influence whatever upon the phenomenon, " and 

 does not prevent its manifestation as soon as 

 the fungus is removed into a dark place." This 

 seems, however, to indicate that the sun's light 

 has, in reality, an influence upon the emission of 

 light by this fungus during the daytime, and 

 that the phenomenon observed by M. Fabre is 

 probably a case of phosphorescence after insola- 

 tion a circumstance not to be passed over slightly, 

 as we see further on, that a similar fact has been 

 observed in the insect world. 



M. Fabre has also shown that the dampness or 

 dryness of the air does not appear to have any 

 influence upon the phosphorescence of Agaricus 

 olearius, unless indeed the dryness is so intense 

 as to desiccate the tissue of the plant. An eleva- 

 tion of temperature, within certain limits, does 

 not modify the phenomenon : below H- 9 to -K 6 

 (centigrade) the light ceases, but the phosphores- 



