LUMINOSITY. 391 



of other grasses are reputed to possess the same 

 properties. 



If we except the milky juice or sap of two or three 

 species, such as Euphorbia phosphorea, said to be 

 luminous, this catalogue will exhaust the principal 

 recorded cases of luminosity in flowering plants ; our 

 last class, which consists of luminous fungi, furnishes 

 numerous well authenticated instances, which might 

 be placed in two classes, of which one would include 

 mycelium, or the root-like filaments of fungi in an 

 imperfect state, and the other perfect or complete 

 fungi. Schoolboys nearly half a century ago had a 

 strong belief in " touchwood " and perhaps the belief 

 still lingers. This " touchwood," consisted of very 

 rotten wood, usually from the heart of a tree, deeply 

 penetrated with the mycelium of fungi, and luminous 

 in the dark. We remember many a cherished morsel 

 which was carried in the pocket, for nocturnal exhi- 

 bition in the dormitory, until " the light of other days 

 had faded," which followed after a few days. One of 

 the most extraordinary manifestations of this class of 

 fungi is recorded by the Rev. M. J. Berkeley. " A 

 quantity of wood had been purchased in a neigh- 

 bouring parish, which was dragged up a very steep 

 hill to its destination. Amongst them was a log of 

 larch, or spruce, it is not quite certain which, 24 

 feet long and a foot in diameter. Some young 

 friends happened to pass up the hill at night, and 



