Manchester Memoirs, Vol li. (1907), No. 13. 9 



In stems with no secondary cortex, this tissue is suc- 

 ceeded by the leaf bases, which are not markedly separated 

 from it. 



(6) Secondary cortex. 



The phellogen arises in the thick walled zone by 

 the division of a belt of cells into 3 by tangential walls. 

 {Fig. 7, Plate III.) The central cell becomes the meristem, 

 and cuts off new cells on both sides. 



The phellogen is very erratic in its development, 

 having begun on certain areas of the stem before others ; 

 thus in the stem A 144, there is at one place a periderm 

 more than 20 cells thick, and in other places the phellogen 

 is not yet formed. 



Occasionally two cells in the same radius will divide, 

 as if to produce a phellogen. In these cases it is possible 

 that the inner really represents the beginning of one of 

 the secretory passages known in L. Wunscliianum (Seward, 

 :00), L. fuliginosnni (Seward, :0l), L. Harcourtii (Bertrand, 

 '91), L. vasculare (Weiss, :0l), Xenophyton radiculosum 

 Hick (Weiss, :02), and Bothrodendron mundum. (Sections 

 A 68, A 128. D. Watson collection.) 



I have been unable to find any definite secretory 

 passages in L. Hickii, but some places where the outer 

 cortex has slightly broken down may represent them. 



Where the periderm reaches any fair thickness it is 

 usually very badly preserved, and it is impossible to 

 determine the position of the phellogen, as the tissue 

 appears thick-walled throughout. 



In radial section the cells of the periderm are 

 arranged vertically above one another and are separated 

 by horizontal walls. 



(7) Leaf trace. 



The connection of the leaf traces with the protoxylem 



