46 
FETCH : 
layer of the solid tip, but in some cases it arises from a deeper 
layer, and the cap then appears double. 
At first sight this cap appears to be a developing pileus. 
But when the mycelium produces pilei, these do not arise 
from the tip, but always on short stalks developed as side 
branches from the older parts. Further, the developing 
pilei differ from the cap in not having a laciniate fringe at 
their margin. That the cord grows on without any change 
in the character of the tip has now been observed in numerous 
instances when the mycelium has been kept growing in the 
laboratory. Hence it would appear that the cap is a special 
structure, though most probably a modified pileus, for the 
protection of the growing point. 
The mycelium adheres to the leaves and branches by means 
of thin discs of fine brown hyphæ which spring from the under 
surface and sides of the cord. These discs may be circular, 
about 0 * 6 mm. in diameter, or oval, up to 3 X 0*75 mm. The 
individual h3rphæ are glued together into a sheet which thins 
out towards its margin, and the same fixing substance (? from 
a degeneration of the outer wall of the hypha) fastens the disc 
to the leaf or branch. On old rough branches these discs 
give rise to a few free hyphæ which wander between the 
fragments of dead bark ; on young green stems and leaves 
there are no free hyphæ, and in neither case have I been able 
to detect any mycelium in the living tissues of the host plant. 
When any part of a stem or leaf with its adhering mycelium 
is placed in alcohol, the fixing substance is apparently dissolved, 
since the whole mycelium separates from the host at the 
slightest touch. This tends to confirm the view that the 
mycelium is entirely superficial. But the individual hyphæ 
of the attaching disc do not separate from each other in 
alcohol. 
These anchoring hyphæ may arise anywhere along the whole 
length of the cord, and their production seems to depend on 
external conditions. If a piece of mycelium is placed in a 
glass dish and kept so moist that it is always in a thin film of 
water, a fringe of brown spreading hyphæ, to a length of over 
a centimetre, develops from each side of it. It would seem, 
therefore, that an abundant supply of moisture at certain 
