1921] MILES—LEAF SPOTS OF ELM 167 
and deposited between their walls. A similar excretion of coloring 
matter was noted by KLEBAHN (22) in working with Gnomonia 
veneta (Sacc. and Speg.) Kleb. Within the looser portion of the 
stroma are to be found in this stage of its development other 
hyphae, which are very thin-walled, entirely filled with a very 
dense protoplasm, and have comparatively few septa. They 
stain pink or red with Pianeze IIIb stain (41), as do the other 
hyphae which enter into the formation of the young perithecium, 
but much more intensely. The ordinary stromatic elements, 
which have become comparatively inactive, take a green color 
with this stain. These deeply staining active hyphae ramify 
through the lower, looser portion of the stroma, a number of them 
turning upward near the center and breaking through to the out- 
side, extending above the leaf surface as shown in fig. 16. 
ASCOGONIUM 
Immediately beneath this portion of the stroma there grows 
downward into the leaf tissue, between the epidermal cells and 
between the cells of the upper palisade tier (usually to a point near 
the lower edge of that layer), one of these hyphae which has become 
slightly larger in diameter. For convenience this hypha may be 
termed an “infection thread’’ or ‘‘suspensor,”’ since it is the first 
of the fungal hyphae to invade the tissue of the host beneath the 
epidermal layer, and since in the early stages of its development 
the young perithecium gives the appearance of being suspended 
from the subcuticular stroma above by means of it. This hypha 
is accompanied in its growth downward into the host tissue by a 
number of other hyphae, consisting of short isodiametrical cells, 
which arise from the basal layers of the stroma and contain com- 
paratively little protoplasm. They form a sheath for the broader, 
more deeply staining hypha, which for convenience only has been 
designated as an infection thread or suspensor. After growing to 
a point about midway down in the palisade layer, this cuts off a 
number of cells at its extreme end (fig. 16), usually three or four, 
which coil somewhat in the form of a spiral. Each one of these 
cells contains two or more nuclei, while the cells of the hyphae 
which constitute the sheath are uninucleate. These hyphae 
