772 
Notes. 
no longer present. For all that, I hold these transitory, incompact 
extrafascicular rings of bundles to be homologous with the more fixed 
and permanent extrafascicular rings of bundles in the vegetative axes 
both of this plant and of Cycads ; the indefinite, strong, vegetative 
growth of the axes in the latter case being the cause of the greater 
fixity, compactness, and stronger development of the extrafascicular 
strands there occurring. The fact that the extrafascicular concentric 
strands of Welwitschia become all used up in supplying the flowers 
does not appear to me to affect the question of their homologies 
in the least ; the collateral extrafascicular strands of the vegetative 
axes of Cycads are dependent for their existence on the presence 
of the foliage-leaves, and take a large part in supplying them with 
vascular tissue ; and they are not present at the apex of the stem 
above the last incoming leaf-traces. 
If the concentric strands composing the outer ring in the axis 
of the cone of Welwitschia do not represent a relic of the same ancient 
structure which prevails in the cauline organs of Cycads, what, I would 
ask, has induced the concentric structure of these strands to appear at 
all ? why do we not find a ring of ordinary endarch strands such 
as compose the central cylinder ? The arrangement and composition 
of these peculiar strands is far too irregular to admit of the possibility 
of their being governed solely by the structural symmetry or other 
characters of the floral axes which they supply ; and, moreover, they 
do not pass obliquely outward to these axes as is the case with the 
steles supplying lateral branches in most axial organs, but form a 
constituent part of the vascular structure throughout the peduncle. 
The small bundles occasionally found within the central cylinder 
may be the sole remnants of a third innermost cylinder of bundles. 
In a peduncle of a female cone of Gnetum which I examined, 
essentially the same structure, as regards the presence of the medullary 
lignified tissue, is exhibited ; but the second ring of strands is in this 
plant reduced to a small, incomplete concentric strand, or an arc- 
shaped row of strands, or a single endarch bundle lying, here and 
there, immediately outside one of the bundles of the central cylinder. 
The inverted strands are almost entirely absent. 
The male cones present no striking features. 
Jodrell Laboratory, Kew, 
October 10, 1901. 
W. C. WORSDELL. 
