Phylloglossmn Drummondii , Kunze. 327 
The occurrence of a stunted leaf in such a position is explained by its 
connexion with the tuber. Earlier in this paper (p. 324) reference was made 
to the fact that a leaf-trace, travelling in the cortex opposite the ramular 
gap, was connected with the stele of the tuber. Such a leaf-trace may 
belong to a normal leaf, or to a leaf in one of the stages of reduction just 
mentioned. So constant is this feature in fertile plants, that of fifteen 
tubers examined, only four were found unconnected with any leaf, and 
these were borne by small plants with relatively few leaves. Moreover, 
a tuber is frequently found bearing more than one leaf, as in the plant of 
Fig. 5, where the steles of two normal leaves and one which is much 
stunted are connected with the stele of the new tuber. Plant b, sketched 
in Fig. 2, was conspicuous both for the number of its leaves and for the fact 
that they were arranged unequally round the axis of the cone. It was 
found that from one tuber five leaf-traces were given off, from the other 
only two. 
The leaf-traces are generally given off from the base of the tuber stele, 
that is, from the part near the parent axis, where the more primitive 
characters are likely to occur (p. 326), but in one case a small vestigial 
strand passed off from the tuber stele at some distance down the shaft 
(Fig. 4, B, r./.). 
The fact that leaf-strands pass off from the stele of the storage tuber, 
some of them supplying leaves which are quite indistinguishable from those 
borne by the main axis, confirms the view that the tuber of Phylloglossu m 
is a specialized branch. Moreover, the stunted growth of certain leaves 
may be correlated with this specialization, since imperfectly developed 
leaves are always those connected with a storage tuber. 
V. Vascular Anatomy of Sterile Plants. 
The resting tubers of Phylloglossmn always produce, on germination, 
one or more roots, a tuft of the characteristic cuneiform leaves, and a new 
storage tuber, but the spore-producing part of the plant may be absent. In 
these plants some of the leaves on the side from which the tuber is given off 
may be reduced, but the different stages in reduction observed in fertile 
plants were not all found. No sterile plant with a second new tuber has 
been recorded. 
Serial transverse sections of a sterile plant show, in general, the 
following stelar structure : At the base of the plant the entering root- 
strands unite with the small strand of the tuber to form a stele, consisting 
of a core of xylem, which seldom shows a definite medulla. From this 
stele leaf-traces are given off, each consisting, as in fertile plants, of a single 
mesarch strand of xylem. As the leaf-traces pass into the cortex the 
stem stele diminishes in size, breaks up, and, before the leaf-bases are free, 
