136 Worsdell—The S true hire and Origin of the Cycadctcecte. 
sought for in two principal regions, viz. (1) in the cotyledonary or primary 
node , i.e. the approximately transitional region between root and stem; for 
it is here that the earliest tissues of the vascular system arise, and we know 
that it is in these tissues, developed earliest in the ontogeny, that ancestral 
traits are most likely to be found and recognized ; (2) the flowering axis, 
for in this region the vascular tissue will have undergone less modification , 
than is the case with the vegetative stem, in the direction of subserving the 
Fig. i a. 
Fig. 1. Encephalartos Barteri : diagrammatic transverse section of the seedling-axis in the 
region of the cotyledonary node, showing the medullosa-like steles (after Matte). Fig. i a. 
Medullosa anglica\ diagrammatic transverse sections of vascular system of stem, showing three main 
steles, two accessory steles, and two leaf-traces (after Scott) : ph — phloem ; px = protoxylem ; 
x l = central primary xylem ; x 2 — secondary xylem. 
exigencies of conduction, and hence ancient characters which may be 
present will tend to be less obscured by the later adaptive accretions to the 
structure. 
If, then, we examine the cotyledonary node of the stem of certain 
Cycads we find structural phenomena which, in my opinion, shed great 
light on the origin of the vascular tissue of the axis as a whole. 
