66 
N. Bancroft. 
considers this structure as being of considerable phylogenetic 
significance, comparable with the three steles of Medullosa anglica. 
In the basal region of a young stem of Macrozamia Denisonii 
(22), concentric strands were seen to occur immediately outside the 
central cylinder; in the same region of a mature stem of Macrozamia 
Fraseri the concentric strands were represented by bands of nor* 
Fig. 14. —A, Encephalartos Barteri. Transverse section of the seedling-axis 
in the region of the cotyledonary node, showing the medullosa-like steles. 
(Adapted from Worsdell, 1906, after Matte). Cf. Medullosa anglica. 
B, Medullosa anglica. Transverse section of the vascular system of the stem, 
showing three main steles, two anomalous steles and two leaf-traces. (Adapted 
from Worsdell, 1906, after Scott). 
xy ', central primary xylem ; xy l , secondary xylem ; ph, phloem ; It, leaf 
traces ; an, anomalous steles. 
mally orientated elements, showing here and there traces of their 
ancestral condition in the presence of small inverted strands on 
their inner side. In the primary node of the stem of Cycas Seemanni 
(22), the first extrafascicular ring was composed of concentric 
strands; this was followed by a continuous zone with collateral 
