24 Lang . — Studies in the Morphology and 
to exist. Omitting some qualifications as to the continuity of the inner 
xylem in the second specimen made in the detailed accounts above, the 
important feature appears to be the continuity of the inner and outer 
xylems from the main stele to the branch. In the case of the outer xylem, 
this involves the secondary development of accessory outer xylem, which 
may be limited to the connecting tracts necessary, or may form over the 
whole stele for a distance of more than two leaf-gaps. Were the branch 
developed at or close to the apex, the connexions would probably be 
expressed in a continuity of the primary tissues, as* is the case in the 
vascular disturbance in relation to some vestigial buds. This has been 
shown above to be comparable with the simpler case presented by the 
vascular connexions of the first branch. In describing the structure, it is 
impossible to avoid the metaphor of departure of tissues from the stele, 
but in interpreting it the other point of view of influences extending 
backwards from the more or less active bud is essential. Similar con¬ 
siderations had to be entertained in studying the vascular connexions of 
branches developed from vestigial buds on the rhizome of Botrychium 
lunaria} 
3. Rhizomes of Juvenile Type. Progression from Juvenile 
to Adult Type. Condensation from Adult to Juvenile 
Type. 
In the preceding pages the structure of rhizomes with medullated and 
distinctly mesarch steles has been described, the origin of the leaf-trace 
and its progress through the cortex has been followed, the vascular dis¬ 
turbance of the stele in relation to the vestigial bud has been analysed, 
and the vascular connexions of branches developed from such buds have 
been described. This section will be devoted to the structure of the stele 
and leaf-trace in small rhizomes of the juvenile type, and to the relations 
between the adult and juvenile types of anatomy. 
The available material has consisted of the two small rhizomes arising 
as lateral branches, of a number of young plants undoubtedly developed 
from embryos, and of some small rhizomes which might have come either 
from small branches, or by further development of embryonic plants. The 
uncertainty (in the absence of the characteristic basal region) is due to the 
fact that the structure of small branches and of plants of embryonic origin 
is essentially similar. Branches of Helminthostachys have not been described 
in detail, though Fig. 2 of Farmer and Freeman’s paper gives the external 
appearance of a shoot of this nature, and the small rhizome, the stele of 
which is figured in Fig. 23 of the same paper, was presumably a branch. 
The anatomy of young plants has been described by Campbell and by 
1 Ann. of Bot., xxvii, p. 235. 
