Ill 
A close inspection shows the presence of white strands on the 
affected branches. These are rhizomorphic strands and constitute 
the vegetative portion of the fungus. On older parts the strands are 
usually thin (‘I c.m) and frequently pursue a zig-zag course, being 
seldom branched. As they pass upwards to the younger branches 
they frequently become thicker (as much as * 2— ’25 cm. in diameter) 
and are repeatedly branched. Here and there a strand may become 
frayed out 011 the surface of a branch and pass into tine fibrils, be- 
coming lost to the naked eye. A branch from a strand passes along 
to a younger twig and growing along the under side of a petiole of a leaf 
reaches the under surface of the lamina; here it branches repeatedly 
and spreads itself over the surface of the leaf until the whole of the 
under surface of the leaf is covered with a white mass of fine fibrils. 
Here and there occur structures which are larger than the 
strands, have an irregular outline and frequently form starting points 
for the origin of fresh strands. 
When a strand comes into contact with an irregularity or rough- 
ness on the surface of a branch, or when it reaches a young bud, it 
produces a dense growth. This also occurs when tne mycelium of 
one leaf comes into contact with another leaf. 
The younger parts of the branches suffer severely from the pre- 
sence of the fungus. 
So efficient is the means of propagation by the strands that when 
a branch is infected all of the young parts become affected by the 
strands. 
Ths Fungus. 
Each strand consists of a central portion or core which is made 
up of hyphae running longitudinally: These hyphae are hyaline, 
measure 4-5 microns in diameter and are septate at long interv a & , 
they are sparingly branched and contain no refractive cell-contents. 
Branches from the innermost hyphae first arise at right angles to the 
parent hyphae and then, bending around, pursue a longitudinal course. 
Branches from the outermost hyphae do not for the most part rim 
longitudinally, but project from the central core and give the strand its 
soft and shiny appearance. 
The larger structures of irregular outline which occur here and 
there on a strand are composed of dense masses of hyphae anc ma> 
be looked upon as undifferentiated scierotia. 
When an affected leaf is placed in a moist chamber in contact 
with healthy leaves the white mycelium first accumulate, a cL - » 
fluffy growth and then spreads to the unaffected leaves. 
I 
SffoO 
