Manchester Memoirs, Vol. li. (1907), No. 13. 7 



This zone of tissue is that in which the cambium would 

 arise, and always occurs in the Lepidodendraceae. 



Succeeding this tissue comes an interrupted belt 

 •16 mm. wide, composed of cells of wide lumen ("05 mm.), 

 each of which is, in well preserved parts, surrounded by a 

 group of smaller cells. {Fig: 10, Plate III.) 



This is the tissue called by Professor Seward the 

 "secretory zone" (Seward, :00, :0I, :02, :o6), and by 

 Professor Weiss " phloem " (Weiss, :oi, :02\ :02 2 , etc.) 



The best preserved parts correspond with the condi- 

 tion described by Professor Weiss (Weiss, :oi) in L. 

 fiUiginosum, Will., and L. vasculare, Binney, and not with 

 that described by Professor Seward. 



This tissue (which I shall call Phloem, following 

 Professor Weiss), is surrounded by an ill-preserved belt, 

 which is presumably pericycle. 



In certain places a single layer of cells, strongly 

 reminiscent of an endodermis, pursues a sinuous course in 

 this ill-preserved layer. 

 Inner cortex. 



The ill-preserved layer referred to above as being in 

 part pericycle also probably represents the inner cortex. 



The more external portions of it consist of thin- 

 walled cells which tend to be tangentially elongated. 



This zone is succeeded by the middle cortex. 



(4) The middle cortex. 



This is composed of large parenchymatous cells which 

 appear to have formed a spongy mass with large air 

 spaces. 



These cells often shew a tendency {Fig. 2, Plate I) 

 towards that elongation and division which leads to the 

 extraordinary middle cortex of L. fuliginosum, Will., 

 (Seward, :oi\ etc.), and Xenophyton radiculosum, Hick 



