1898-99.] | MORPHOLOGY OF THE CENTRAL CYLINDER IN THE ANGIOSPERMS. 
while other species are astelic. Anemone nemorosa belongs to the latter 
class and is described by Marié* as having the individual bundles sur- 
rounded by phlceotermal sheaths. A. pennsylvanica has, according to the 
same author,” a continuous external phlceoterma surrounding the 
whole complex of bundles. The writer’s discovery of an internal 
phlazoterma in the young stems of various so-called monostelic species 
of Ranunculus, has suggested the examination of the younger region of 
the subterranean axis of this species of Anemone. Photograph 19, 
plate 10, reproduces a section of the quite young hypogzous stem of 
A. pennsylvanica. The stelar system is interrupted by a foliar gap, 
around the margins of which the internal and external phlceotermal layers 
are in communication. Photograph 20, plate 10, represents an older 
region of the cylinder where it is interrupted by numerous foliar gaps, 
The segments of the stelar tube are, in this case, individually sur- 
rounded by phlceotermal sheaths. In the older region of the hypoge- 
ous stem, it becomes continually more difficult to distinguish the 
phlceoterma on account of the sclerification of the pericycle, and, ulti- 
mately, of the phloeoterma itself. 
The young stem of A. cy/zndrica has also been studied in this connec- 
tion, but in this species, even the outer phlceoterma is very poorly 
developed, and the internal one is obsolete throughout. The absence of 
a well-marked phlceoterma in the hypogeous stems of the genus 
Anemone has been especially noted by Janczewski,“ and accordingly, 
it is not surprising that this feature should be exemplified by A. cy/in- 
drica. 
The writer has also examined the stem of the closely allied genus 
Hepatica. In the seeding of Hepatica triloba, there is a well-marked 
external phloceoterma, but the internal phlceotermal sheath is not differ- 
entiated at all on account of the sclerification of both the pericycle 
and the external layer of the medulla. The latter features may be 
seen in photograph 30, plate II. 
In connection with the Ranunculacez may be described the structure 
of the young stelar system of Sarracenia purpurea. In this species, the 
young central cylinder is tubular with foliar lacune. The external 
phlceoterma is poorly developed and the corresponding internal layer 
cannot be distinguished even in the very young axis. 
The reader who has followed the descriptions given in the foregoing 
42. Op. Cit., p. 56. 
43. Op. Cit., p. 62. 
44. Op. Cit., p. 3. 
