148 



LYCOPODIALES 



[CH. 



This band of meristem, which we may speak of as the cambium, 

 occurs in the outer region of the meristematic zone immediately 

 internal to the secretory zone, sc. 



The result of the activity of this cambium band is the 

 production of secondary parenchyma and tracheal tissue. In 

 fig. 179, E, drawn from a portion of the section represented in 



a Sc 



m--i 



W^Btfi 



Fig. 168. A. Lepidodendron vasculare. (Botany School, Cambridge.) 



B. Lepidodendron fuUginosum. (From a specimen from Shore, 

 Lancashire, in the Cambridge Botany School Collection). 



C. L. fuUginosum. ("Biseriate Halonia " of Weiss No. 257, 

 Manchester University Museum.) 



D. L . fuUginosum. (Manchester Univ. Museum.) 



lig. 168, B, a projecting arm of primary xylem is seen at x ; 

 this is followed by 2 — 3 layers of parenchymatous cells, some of 

 which have dark contents, and beyond this is seen a group of 

 secondary elements, tr, cut across somewhat obliquely, which 

 are evidently products of the cambial cells on the inner margin 



