124 
may occasionally be produced by artificial inoculation. (Test 
Fig. 8.) Pycnidia have never been found on the leaves, 
At first the fungus mycelium spreads in the cortex of the 
d ’ s 7” 
be regarded as distributive in that it consists of elongate little 
branched hyphae which penetrate the tissues principally in a 
direction parallel to the axis of the host. Later the mycelium 
the host tissues. From the cortex the hyphae pass to the phloem 
groups and thence along the medullary rays to the pith, in which 
the fine mycelium is very abundant. (Text Fig. 9.) 
9a. Hyphae of fungus ramifying in yj 
9b. maitying in pith cells of host. 
oat om passing through pits in the walls of pith cells of host. 
Yphae are very slender and freely branched. 
From the medullar 
y Yays and phloem eroups the hyphae 
= als din = elements, branching little, but either run- 
* to their bipth. y through them or crossing at right angles 
The hyphae enter th 
: e cells through th ‘ts which are 
shundantly nay wi: in the walls—(Tent Fig. band where & 
matous se Sack tng a deep pit as in the walls of sclerenchy- 
(PLY. Fi eldal _clements a definite constriction is visible. 
- V., Pigs. 6, 7, 8.) ; 
_At point of ent : . 
weg is present ih the byrne a pit an appressorium like 
e cells of the corte hl . diy 
i ’ oem, 4 b rapl hf : 
appears to PuageePL Vad 9: PVE Fig. cand 
‘The cell walls a ae oe : be, kind on the part of the 
: : eem to free , an 
aoe of enzyme acticn eould He tinoraa. oaege 
