Life history of a new species of Sphaerella 
191 
other from the ends of short branches. This conidia formation resembled 
very closely that found in cultures of certain species of Fusarium. 
The production of this type of spore soon ceased and the further 
development is very similar to that described for the cultures of the 
imperfect stage. 
Fig. 2. 
xMycelium within the 
cells of the host leaf, 
showing constrictions 
where passing through 
walls of host cells. — 
2 A later stage, showing 
the partial disintegration 
of cell walls. — 3 and 4 
Early stages in the for¬ 
mation of a pycni- 
dium. — 5 Mature 
pycnidium. — dSper- 
mogonium containing 
spermatia. — 7 Very 
early stage in the for¬ 
mation of perithe- 
cium. —8 A later stage, 
showing carpogonical 
branch surrounded by 
anastomosing branches 
which form the perithe^ 
cial wall. — 9 Section 
of a perithecium at 
a still later stage showing 
ascogenous hyphae ari¬ 
sing from the cell in the 
base of the perithecium. 
— jo Mature perithe¬ 
cium with asci and 
spores in various stages 
of development. — 11 
Mature ascus,showing 
break in the outer sheath 
of ascus wall. — 12 
Mature ascus,showing 
broken and collapsed 
outer sheath and expan¬ 
ded inner membrane of 
ascus. — 13 Conidio- 
phores and conidia 
from agar culture of asco- 
spores, seven days old. 
Inoculations. 
A small plant of Prunus pennsylvanica , which had been brought 
into the green house and planted in a pot, was inoculated by placing 
drops of water containing pycnospores from an ascosporic culture on the 
underside of its leaves. This plant with another used as a check were 
covered with bell jars. 
The first inoculation had failed to produce infection at the end ot 
two weeks, so the same plant was used again. This time newly formed 
pycnospores from an ascosporic culture were used. On the fifth da) spots 
