412 Scott. — On Peduncle of Cycadaceae. 
present in connexion with a single bundle, but their occurrence 
is very inconstant. 
The course of the bundles was traced in peduncles which 
remained attached to a very old stem of this species, 
embedded among the leaf-traces. They had lost their cones 
some time before, but were probably of no great age, as they 
occurred near the apex, and their structure was still intact. 
The general vascular arrangement in the lower part of the 
peduncle is essentially the same as in S t anger ia. Quite at 
the base there is a small ring (about 3x4 mm. in diameter) 
of perfectly normal bundles ; a little higher up the ring 
enlarges, and becomes more elliptical, measuring about 
10x5 mm. The bundles at the narrow ends of the ellipse 
are crowded and irregularly orientated — obviously as the 
result of development under pressure from the leaf-bases 2 . 
A more remarkable anomaly is the presence of inverted 
cortical bundles immediately outside those of the normal 
ring. Some of these bundles, where they pass further out 
into the cortex, show some approximation to a concentric 
structure. 
Further up still, the ring of bundles again becomes regular, 
but as the cone is approached, new peculiarities make their 
appearance. The principal bundles are no longer equidistant 
from the centre but form an irregular double ring, with 
variable orientation of the individual strands. Small bundles 
enter the pith ; when traced up into the axis of the cone they 
are found to pass out, usually fusing, as they do so, with the 
principal strands. The same arrangement was shown in 
a male cone of C. talifolia , Miq., but it does not appear to 
be constant throughout the genus. In C. latifolia also, slight 
traces of centripetal xylem were observed. 
The peduncles of a number of other Cycadaceae of the 
genera Cycas ( J ), M acrozamia, Ceratozamia , and Zamia were 
examined, without, so far, finding any other clear case of 
centripetal xylem. The instances, however, in which it has 
1 Cf. Solms-Laubach, 1 . c. p. 212. 
