1 8 MacDougal . — Symbiotic Saprophytism. 
and contain hyphae which may be traced to the cortex 
beneath. The outer layers of the cortex contain numbers 
of raphide-bundles. The cortical cells are globose or greatly 
irregular, and are arranged in about twelve to fifteen layers. 
The outer layers contain simple hyphae chiefly, but also 
some cysts of Fungi which are most numerous in the median 
portion. Numbers of these formations are to be found in 
the cells next to some of the inner cortical cells, and the 
sheath contains starch. It is impossible to distinguish clearly 
the exo-cortex, medio-cortex and endo-cortex, as made out 
by Groom (13) in other saprophytes, upon the basis of the 
relative distribution of the Fungus and of starch. The starch 
is found in greatest quantity in the tissues near the apex, 
and in that region granules were actually present in cells 
which harboured the Fungus even in the external layers. 
The sheath consists of flattened cells with directly transverse 
end-walls, and all of the members are slightly thickened. The 
sheath is interrupted in places by small passage-cells. The 
fibrovascular bundles occupy a single irregular circle with 
the phloem external, radial to the xylem, and consisting 
of sieve-tubes, companion-cells and parenchyma. The xylem 
consists of one or more spiral vessels, a few scalariform ducts, 
and some obliquely perforated libriform vessels. The inner 
circle of bundles is represented by a few irregularly placed 
spiral ducts which most probably represent atrophied bundles. 
It is to be seen that the cross-section of the conducting 
tissues is much less than in the normal offshoot. The apices 
of the branches so closely resemble that of Corallorhiza , as de- 
scribed by Reinke, that no detailed description is necessary (33). 
The apex of each branch is flattened and covered by arched 
scale-leaves which soon fall away leaving only the leaf-trace 
to mark the internode. The meristem-cells exhibit division 
in every direction, and only the dermatogen is clearly differen- 
tiated. The fibrovascular tissues extend to within *5 mm. 
of the surface of the meristem. The method of branching 
is quite similar in detail to that figured by Irmisch (15) for 
Corallorhiza. The roots of coralloid plants are almost free 
