234 A. G. Tansley. 
The petiole of Marattia fraxinea, at the level of the pulvinus, 
shows either a single circle of strands enclosing a central one, or 
two concentric circles enclosing a central strand, as in the stem. 
Fig. 78. Angiopteris cveclu. Transverse section of stem showing four or 
five concentric circles of mcristeles. The circles tend to run one into the 
other, giving a spiral arrangement. Protophloems represented by dotted 
lines ; protoxylems by larger dots. The dotted lines bounding parts of the 
section represent leaf-bases cut away. R, roots. From Shove. 
None of these internal strands is directly connected with any cauline 
strands, but they arise by branching of members of the outer 
circle, i.e. of strands belonging to the original leaf-trace curve. 
Traced upwards they disappear by successive fusions, first of the 
