57 
ono-celled, colorless, oval to pyriform, surrounded by a thin gelatinous 
envelope, and measure 10-14 by 5-7//. They have a striking resem¬ 
blance to the spores of Glceosporium nervisequum. 
Jt is evident from the form of the open conceptacle that the fungus 
belongs to the Excipulacece. It agrees perfectly with the description 
of Disculaplatani Peck (Sacc. Syll., Vol. Ill, p. C>94). 
On account of its mode of development Discula platani must be re¬ 
garded as a pycnidium, but it differs in several points from what we 
usually call pycnidia. The body of tissue remains intact longer than is 
usual and it is also different in being differentiated into two kinds of 
tissue. The upper part of the pycnidium with the elongated cells cor¬ 
responds with similar formations on the walls of other pycnidia, as will 
be shown below in case of Fcnestella (Fig. 11). The pore always makes 
its appearance at the spot where the elongated cells were developed. 
In Discula this attains such very considerable dimensions that the en¬ 
tire pycnidium is destroyed down to the bowl-shaped basal portion, and 
besides this the phenomena of growth are peculiar to Discula. Discula 
does not, however, stand alone in this. Banke (Beitr. z. Keuntn. d. 
Pycnidenin Nova Acta Acad., Leopold., XXXVIII, p. 481) demonstrated 
an apical growth of the pycnidia of Pleospora polytriclia. 
Nothing is known concerning the farther development of the Discula. 
In fact it was only in rare cases that we succeeded in following the 
development until the kymenium was exposed. A few days after the 
branches were brought into the house Tricothecium roseum attacked the 
pycnidia where they had broken through the bark and completely de- 
stioyed them. 
When sowed in water or nutritive fluid the spores of Discula germi¬ 
nate in about twenty-four hours. They generally give rise to two, more 
rarely one or three, germ tubes, which swell up, forming spherical 
bodies. The growth is at first similar to the budding that occurs in 
yeast, showing repeated branching and budding, surrounding the spore 
in a dense tangle. One of the branches finally exhibits a decided 
apical growth and develops into a hypha branching inonopodially. 
Xo septa are present for some time, but they appear later in consider¬ 
able numbers. A vigorous mycelium develops rapidly but it never at¬ 
tains the production of spores. Frequently a few cells either at the 
ends or along the course of the hyphae swell up and assume a spher¬ 
ical shape, and sometimes this happens for two adjacent cells ; in the 
latter case the sphere is divided by a septum. The contents is watery 
and the protoplasm simply forms a lining within the wall. 
Leaves and branches of Platanus were inoculated with Discula in the 
same manner as with the Glceosporium but with no results. The leaves 
remained fresh for a long time and then began to wither and turn 
brown without showing any signs of a fungus. 
Discula platani is found on dry branches of Platanus during the entire 
year, and it was once discovered upon the petiole of a large decaying 
