THE OLDER SPOROPHYTE 



199 



approach, but are still separated by a considerable mass of tissue, lying directly 

 under the stem apex. The two bundles finally join and between them there seems 

 to be a sort of connective tissue which may perhaps belong to the stem itself, so 

 that this central stele of the stem may possibly have a certain amount of cauline 

 tissue in addition to that derived from the leaf traces; but it is quite as likely that 

 this connective tissue between the bundles is nothing more than a lateral extension of 

 the leaf trace itself, very much as is the case in Helmtnthostachys and Botrychium. 



Fig. 1X1. -Series "I transverse sections from a sporophyte of Angiopteris, showing 5 leav< s. 

 r 2 , r 3 , second and third roots. X25. B, traverses the stem apex. 



When the fusion is complete, the section of the stele appears circular in outline 

 and the whole of the tissue is apparently quite uniform, with the exception of a single 

 tracheid marking the position of the xylem of the older leaf trace. There follows 

 almost immediately the older leaf trace which joins the solid stele, formed by the 

 fusion of the traces from the third and fourth leaf, without causing any break. At 

 this level the first tracheary tissue can be seen in the fourth leaf trace also. 1 he 

 structure of the stem below the junction of the second and third leaf traces is the 

 same as that already described for the younger sporophyte. A very young root was 



