416 Proceedings of the Microscopical Society. 



l,)lt:hAd been conjectured by Sohlelden that a current existed between 

 the gelatinous contents of the cell and its walls, which preceded the for- 

 mation of a fibre, and gave the direction it afterwards took ; this was re- 

 futed by shewing, that the granules became separately attached to the 

 inside of the vessel, at a little distance from each other, beginning first at 

 one end and proceeding to the opposite ; the fibre elongating like a root, 

 by the materials of growth being always added to the point. The gra- 

 nules so attached, becoming nourished by the contents of the vessel, and 

 the spaces between them, are in a short time obliterated by the fibre ac- 

 quiring a defined border which completes its development. 



This act is the one observed in the formation of the fibre of all vessels, 

 but the arrangement of the granules differs so as to constitute the seve- 

 ral varieties. In the annular vessel the granules attach themselves hori- 

 zontallj', forming rings. In the spiral they become inclined, and by con- 

 tinuing this direction around the interior of the membranous tube, the 

 peculiar character of the vessel is obtained. In the reticulated, each di- 

 vision or branch of the fibre or granule becomes enlarged in the line, and 

 forms the starting-place for the fresh direction of the fibre. In the dotted 

 and scalariform vessels, the fibres become so reticulated as to have por- 

 tions of the outer membrane of the vessel without anj- deposit within ; 

 and this spot so left, constitutes the dot or linear marking seen in these 

 vessels. 



This dot is plain in all such vessels, excepting those found in woody 

 exogens, where it possesses (from a slight difference in structure) a cen- 

 tral mark analogous to that on the woody tissue of coniferous plants with 

 which Mr Quekett considers it identical, but only of a smaller size. The 

 paper was illustrated with numerous diagrams, which gave representa- 

 tions of the successive stages of the minute process Mr Quekett had ob- 

 served. 



SCIENTIFIC INTELLIGENCE, IN GEOLOGY, 

 MINERALOGY, &c. 



1. Lanta7i, a new Metal. — Mosander ha.s detected, in the 

 cerite of Bastnas, a new metal, whicli he names Lantan* The 

 oxide of cerium, obtained by the usual process from the cerite, 

 contains two-fifths of its weight of the oxide of the new metal, 

 which alters the properties of cerium very little, and was thus as 

 it were concealed in it. Hence Mosander names the new metal 

 Lantan. Kersten of Freyberg has fomid this new metal asso- 



• Lantan, from Xuvinvuv, to be concealed. 



