502 Shove.—-On the Strticture of the 
The upper surface of the naked cone that forms the base 
of the stem is brown and rough, and bears at intervals frag¬ 
ments of vascular tissue that have been exposed by the 
wearing away of the softer parenchymatous tissues. The 
under side, however, shows traces of an original surface, and 
bears several circular pits (Fig. i, r), which have their origin 
in the decay of the tissues of the roots. 
The stem is about 25 cms. in length, reckoning from the 
tip of the bare base to the summit of the smallest leaves 
visible from the exterior. In its widest part, that is, nearest 
the apex, it reaches a diameter of about 8 cms., and from 
this point it diminishes in diameter to about 1 cm. at the base. 
The upper surface of the stem is bare for 3 cms. from the 
lower conical end, but here the first leaf (Fig. 1, a) occurs, 
somewhat shapeless owing to the wearing away of the tissues. 
From this point onwards no free surface is exposed on the 
upper side of the stem, but leaf-bases, closely wedged 
together, increase in number and size. The shapeless character 
of the lower leaf-bases is clearly seen in Fig. 1. 
The lower surface of the stem bears no leaves for a distance 
of 8 cms. from the base, but is densely covered with roots. 
These emerge directly from the free part of the stem, and, 
as will be seen later, the arrangement of the vascular network 
is modified in this region to facilitate their passage to the 
exterior. The roots occur for the most part in a definite 
region on the lower surface of the stem, which bears also one 
small leaf-base. This leaf-base, together with the lowest of 
those occurring higher up, is penetrated in every direction by 
roots, so as to almost obliterate the tissues of the leaf-base 
proper. Further up the stem the roots occur singly, making 
their way to the exterior either between or through the leaf- 
bases. Correlated with this diminished production of roots is 
a tendency on the part of the stem to assume a radial rather 
than a dorsiventral structure. 
Owing to the incomplete development of the younger parts 
of the stem, it could not be determined with absolute certainty 
whether a radial structure is present in the plant during the 
