PAPERS ON BOTANY 233 
SPORES 
In each ascus are produced eight unicellular, hyaline, thin- 
walled spores. They are ovate in form with round ends and 
vary in length from 7.2 » to 12 » and in thickness from 4.5 p» to 
7.2. Usually they are uniseriate but there are occasional ex- 
ceptions to this arrangement when the ascus is relatively short 
and the spores biseriate. Stained microtome sections show a 
very prominent nucleus. 
The fungus is obviously of the Dothidiaceae and has been 
identified by the writer as Phyllachora graminis ( Pers.) Fuck. 
Which is found on many grasses in this country but has not 
been reported on corn. It conforms with the description of 
Phyllacora graminis in Saccardo’s “Sylloge Fungorum,” and 
with the description by Winter”, Lindau”, Elis and Everhart’, 
and Sydow and Theissen”, Boltshauser’ describes P. graminis 
as having numerous, small stromata in living tissue and a few 
relatively large stromata in brown, dead leaves. This varia- 
tion in the appearance of the stroma, from small and numerous 
to large and relatively few in number, is not considered by 
Sydow and Theissen of any importance in classification. 
In my specimens the position of the asci in the perithecia does 
not conform to the description of P. graminis by Fuckel’ or by 
Miiller “, the former claims that the asci grow from the base 
of the perithecia, the latter that they form an equatorial ring 
in the shape of a girdling band around the center of the peri- 
thecia. My specimens have the asci developing from the base 
and from the inner basal circular surface, up to about half the 
interior of the perithecia with the free ends extending toward 
the center. Microtome sections were made for comparison 
from available exsiccata. Nine specimens, from different 
hosts, identified as Phyllachora graminis were sectioned and 
examined. Each one had the asci developing similarly to those 
of the fungus on corn, and this mode of development seems 
to be constant. Sydow and Theissen™ consider the position of 
the asci in the perithecia to be of specific import and my speci- 
mens agree with their description of P. graminis in this re- 
gard. 
A peculiar distention of the basal centers of the perithecia 
is sometimes described but was not observed in the material 
