.354 BOTANICAL GAZETTE [may 



with occasional scattered sieve tubes and parenchyma cells. All 

 these strands — the two produced by the splitting of the ring of 

 xylem about the leaf trace, the strands which arise in the pericycle 

 of one of those, and the tangled mass which is both accessory and 

 pericyclic in origin — fuse to form the branch stele (fig. 6, H). Hence 

 the vascular supply of the branch consists of (i) centripetal second- 

 ary xylem, (2) accessory secondary xylem, and (3) primary and 

 secondary pericyclic xylem. 



In other cases, numerous scattered tracheids appear in the pith 

 below the point of separation of the leaf trace (fig. 9). As the trace 

 leaves the stele, some of these swing out with it and contribute to 

 the vascular supply of the branch. In such cases, there is not the 

 slightest evidence of an internal cambium. Primary centripetal 

 xylem of this kind occurs in the vascular supply of five of the nine 

 branches, while abundant centripetal secondary wood is present in 

 the other four. 



It is not necessary to describe in detail the vascular connections 

 of the other branches. Accessory secondary wood usually forms a 

 considerable part of the supply and is present in every case. In 

 six of the nine branches, wings of xylem form between the leaf and 

 the trace and the stele, as in B. ramosum; in the other three such 

 formations are entirely lacking. Xylem of pericyclic origin makes 

 up a part of the connection in five cases; in three of these a 

 definite cambium is present. The accessory secondary wood 

 is the only formation which occurs in all the nine cases of this 

 species. 



The significance of the wide variation in the vascular supply of 

 the branches will be discussed later. 



WOUND REACTIONS 



Jeffrey (7) has put forward the view that traumatic reactions 

 are apt to be reversionary in character. Bower (i) and Lang (9) 

 have used this view in their contention that the pith of the Ophio- 

 glossaceae is stelar in character. In the examination of branching 

 specimens of Botrychium, especially of B. obliquum, some further 

 data upon the nature of the wound reactions of this genus have 

 been secured. 



