LONGEVITY OF PLANTS. 



657 



seuras have secured specimens of them for their collections. It is hard 

 to get large ones, and they command a high price. At first, their true 

 nature was misapprehended. They were regarded successively as in- 

 crustations formed around roots that had disappeared ; as the cells 

 constructed by worms of extinct species ; and as a kind of stalactites. 

 Hentzen seems to have been the first one who attributed them to light- 







Fig. 2. Fulgurites. Tubes produced by tbe vitrification of sand by the passage of lisrhtning 

 tbrough the soil in the deserts of Poland. (From a specimen in the'Museum ; figure one third 

 the natural size.) 



ning ; and his opinion has been shown to be correct by Blumenbach 

 and by Tiegler. More recently, Nature has been caught in the act ; 

 that is, fulgurites have been found in sand which was still hot, at the 

 spot where the lightning had been seen to strike. Besides, several 

 experimenters, as Beudant, Huchette, and Savart, have obtained tubes 

 analogous to fulgurites by discharging the great electrical battery of 

 the Conservatoire des Arts et Metiers through beds of pounded glass, 

 or of sand mixed with sea-salt to make it more fusible. Fulminated 

 tubes are found principally in places where beds of sand lie upon a 

 soil which contains water, and is consequently a conductor of electric- 

 ity ; for example, at certain points in Silesia, in Eastern Prussia, Poland, 

 Cumberland, and Brazil. 



LONGEVITY OF PLANTS.* 



By F. IIILDEBBAND. 



THE extremes between which the duration of the lives of plants 

 varies are widely removed from each other. On one side, we 

 may see plants that begin and close their lives within a few hours or 

 days ; on the other side, plants, the lives of which may be estimated 



* Translated from " Das Ausland " for " The Popular Science Monthly." 

 VOL. xx. 42 



