CYLINDROSPORIUM ON STONE FRUITS 
in some material from the same tree killed December 28 in Carnoy's 
alcohol acetic acid fixer, many stromata show apparently healthy coils. 
Later than this they were not seen with certainty. 
The pseudoparenchymatous covering of the stroma separates the 
layer of microconidiophores which now gelatinize and glue the rem- 
nants of the epidermal cells to the surface of the stroma. The cells 
of the pseudoparenchymatous covering as well as the mycelium in the 
leaf tissue become thick walled and dark colored. 
The stroma usually extends entirely through to the upper epi- 
dermis, but remains covered both above and below by the leaf epi- 
dermis. It is apparent only because of the dark color, and in this 
condition the fungus passes the winter. 
During the first warm days of March the stroma begins to swell 
toward the lower (dorsal) surface of the leaf, and when sectioned this 
swelling is seen to be due to a row of erect parallel hyphae which later 
are seen to be paraphyses. The asci do not appear until about the 
first of April or later. They develop from branched ascogenous hyphae 
which arise near the base of the stroma. During the latter part of 
April and the first of May the asci enlarge rapidly and lift the covering 
until it finally breaks in a more or less stellate manner. The break 
occurs before the ascospores are mature, but they mature in a very 
short time thereafter. 
The asci open by a pore in the papillate apex and the spores are 
shot out. On taking leaves, in which the ascospores are just mature, 
from a moist chamber, clouds of spores have a few times been seen 
shot out from the under surface. 
After the ascospores are shed the asci and paraphyses disappear, 
and long slender conidia are formed on short conidiophores which 
arise apparently as branches from the base of the paraphyses. They 
are once or twice septate and resemble Cylindrosporium conidia but 
are usually longer and a little more slender. 
Besides being on P. avium this type of fruit body and development 
was found on P. pennsylvanica and P. cerasus. 
In the other type, found on P. domestica, P. insititia, P. virginiana, 
P. serotina and P. mahaleb, the stroma develops beneath the lower 
epidermis and does not extend into the leaf tissue to any appreciable 
extent. The development is more outward, thus protruding and form- 
ing rather prominent disk-shaped to flattened-globose bodies on the 
under side of the leaf. 
