KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 201 
(scalariform-retieulate). In addition there run in the centre of 
the stele little bundles of very narrow spiral vessels (PI. VI. fig. 9), 
which may or may not be connected with the bundles of 
tracheides. In transverse sections some of the spiral vessels are 
in connection with the tracheides: hence it seems probable that 
they are portions of these bundles which are undergoing atrophy. 
It is possible, however, that the isolated spiral vessels repre- 
sent other bundles which have almost disappeared, inasmuch as 
the bundles of tracheides are less numerous than the bundles 
of phloém. 
The bundles of phloém are better developed. They consist of 
sieve-tubes, companion cells, and parenchyma. There are three 
bundles between the groups of xylem, and these are laterally 
connected with small groups outside the bundles of xylem, so 
that an incomplete ring of phloém is formed. 
For the rest the stele is composed of parenchyma with thin 
unmodified walls. 
No mechanical tissue exists in the rhizome. 
At the base of the rhizome on one side there was, in both my 
specimens, a minute bud in the axil of a microscopical scale. 
Below this, at the immediate region of its attachment to the 
tuber, the rhizome narrows considerably, owing to a diminution in 
the number of cortical layers. Mycorhizal hyphæ do not pass 
through this constricted region into the tuber. 
Histology of the Radiating Root-like Processes. 
Examination at once reveals the fact that these repeat the 
‘structure of the rhizome described, and are therefore modified 
stem-structures. The epidermis has stomata; the multicellular 
protuberances with their terminal hairs are numerous. The 
layers of cortex are smaller in number, being most numerous 
at the proximal end (six layers at most). All these layers, ex- 
cepting possibly the innermost which lies without the endodermis, 
contain coiled mycelia. No starch is present in any of the 
layers excepting in the inner layer when it has no mycorhizal 
hyphe. The endodermis and stele are merely small versions 
of the same structures in the main rhizome. The apices were 
not perfectly intact, but they were sufficiently preserved to allow 
the statement that no root-cap was present. At its point of 
attachment the root-like process becomes constricted like the 
main rhizome (Pl. VI. fig. 5). At this constricted region the 
cortical cells form a more or less complete layer of cells with 
