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ON A NEW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc. 
increases in size and at last produces a pyenidium. The pyenidia, even in 
the matured stage, are only cavities in the stromata, and their wall is not 
clearly distinguished from the surrounding tissue of the stroma. Their size 
and shape are also various and irregular. The pyenidial cavity is almost 
single in a cross-section of a stroma at first. In a single cross-section of a 
matured stroma, a few or several disconnected irregular shaped cavities are 
usually to be seen (PI. IX, Fig. i .). But if the entire stroma is cut into serial 
sections, it shows clearly that there is but a single pyenidium with a number 
of communicating chambers, having a single exit. 
The conidiophores form a dense hymenium on the inner wall of the 
pyenidium, extending directly out into the cavity from every point of the 
wall. They are of uneven lengths, the majority being 14-28 ft long, and are 
about 1.75-2.1 a in diameter. They are much longer in the pyenidial cavity 
produced on pure cultures, reaching about 40-60 /Jt in length. They may be 
simple or branched (PI. IX, Fig. 9.). Spores are cut off successively from the 
conidiophores and soon fill the cavity, but since the production of the spores 
does not cease when the cavity is filled, they are forced out through an ostiole 
at the top in a reddish spore horn. The spore horn is usually spirally twisted 
into coils or other various shapes. In cultures, the spores are exuded in drops 
instead of horns because of the too great moisture present. 
The reddish tendrils are composed entirely of the small hyaline pyeno- 
spores held together by a binding substance. When placed in water, the 
tendril first swells and turns white, then the binding substance dissolves and 
the spores float away free from each other. They commonly measure 5.25— 
10.50 x 1 .4-2. 1 a in size. But the sizes of the pyenospores are very variable in 
accordance with the grade of their maturation; and the difference between the 
maximum and minimum sizes is remarkably wide, e.g., 3.5-15.75 x 1.0— 2.63/i. 
Such vacillation of the spore size is most commonly seen on pure cultures. 
They are cylindrical, ailantoid with rounded ends, usually curved but 
sometimes straight. The spore-wall is smooth and colorless (JP1. IX. Fig. 2.). 
From the characters of the pyenidia and the pyenospores as described 
