Rhizome of Matonia pectinata. 159 
importance.” As Mr. Jeffrey 1 has shown in the case of Pteris 
aqiiilina the arrangement may vary even in the same stem. In 
Pteris a solid axial stele, with no ground tissue enclosed, was found 
up to the origin of the fourth or fifth leaf and then a core of ground 
tissue appeared inside the internal phloem. 
Longitudinal sections through the apical region show that the 
steles arise from a common meristem, and that the innermost 
siphonostele is from the commencement a hollow tube (fig. 7). The 
steles appear emerging from the meristem as six bands of light- 
coloured tissue, separated from each other by the darker parenchy¬ 
matous cells of the ground tissue, and gradually diverging into the 
thicker and more mature rhizome. 
The connection of the three steles one with another, as 
described above, also differs from that described by Mr. Seward in 
the rhizome with the central axial stele. Comparing figs. 1-6 with 
Mr. Seward’s fig. 5, it is seen that fig. 2, showing the connection 
between the innermost and middle steles in front of a node, 
corresponds with section 1 of Mr. Seward’s figure, except that here 
there is a central mass of ground tissue present. But while 
section 2 of Mr. Seward’s figure shows the middle stele open and 
the central stele still connected with it, in my specimen the inner¬ 
most stele separates from the middle stele as soon as a gap occurs 
in the latter (fig. 3) and these two steles remain separated 
throughout the node. The opening of the middle stele takes place 
immediately after the fusion with the innermost stele, and it 
remains open until a fusion takes place with the outermost stele 
just before the leaf trace is given off (fig. 5), when it closes and 
remains, like the inner stele, closed throughout the node. The 
outermost stele does not open until the middle one is closed, so that 
two of the steles are never found open at the same time, as shown 
in section 3 of Mr. Seward’s fig. 5. 
The apical region is broad and lies in a depression, the under 
side of the rhizome projecting much more than the upper one 
( up . in fig. 7). It is protected by numerous multicellular hairs. 
In a median longitudinal section (see fig. 7), a slight rounded 
protuberance at one side (/) with a large dome-shaped apical cell 
indicates a developing leaf. Mr. Seward has found a similar dome¬ 
shaped cell at the apex of the young pinnules. 
The actual apex of the rhizome (si) is occupied by a single cell 
of larger size than the surrounding cells and appearing more or less 
*E. C. Jeffrey. Memoirs of the Boston Society of Natural 
History, 1899. 
