KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 179 
cells forming this sheath are more marked on the radially external 
part of the bundle. 
The phloém consists of sieve-tubes, companion cells, and elon- 
gated parenchymatous cells similar to those occurring in the 
root. But the last-named have wider lumina and very large 
oval nuclei. 
The xylem is separated from the phloém by a transverse band 
(in transverse section)of longitudinally elongated parenchymatous 
cells with peculiar square nuclei. Within succeeds a single, or 
double, tangentially extended line of trachee with transverse 
pits. The protoxylem is clearly represented by a radial series 
(fig. 11) of spiral and annular vessels lying in a mass of paren- 
chyma with thin unmodified walls. 
Histology of the Rhizome 
(at or below the attachment of the highest roots). 
Compared with the scape, there is a large increase in the size 
of the cortex and a dwindling of the stele. The cortex, outside 
the general sheath, is constituted of nine layers of parenchyma 
which is rieh in starch. Further, the ground-tissue within the 
stele is changed into parenchymatous cells with thick lignified 
and pitted walls. These are easily distinguished from the sheath- 
fibres by their wider lumina and lack of narrow pointed ends. 
In one rhizome I found a young bud had been adventitiously 
produced from a terminal scar where the rhizome was under- 
going decay. Similar buds are produced from isolated broken 
fragments of the rhizome of Lathrea squamaria. 
Histology of the Upper Parts of the Scape. 
The diminution in thickness in the higher regions of the scape 
is due to the reduction of the size of the stele, within which 
there are fewer vascular bundles. The bundles are smaller, and 
the reduction of the xylem is most marked. The cells of the 
general sheath and of the bundle-sheaths have thinner walls 
than lower down. Hairs and stomata occur. Such is the ap- 
pearance of the upper part of an old scape bearing fruits and 
mature flowers. But when the scape terminates in a bud con- 
taining rudiments of flowers, the appearances are different. The 
young parts of the scape and the inner faces of the young scales 
are coated with glandular hairs pouring out mucilage. Thus the 
