TAKEWO HEMM I 269 
above, we easily recognize our fungus to be a species belonging to the genus 
Cytospora of Sphaerioidaceae. 
c. Perithecia. 
The matured stromata on the older cankers have numerous projecting 
papillae on the external surface, especially near the margin. A cross-section 
of a stroma shows the subglobose sac-like perithecia each with a long black 
neck (PI. IX. Fig. 3, 5.). Generally, there are fifteen to forty perithecia in a 
stroma, but the number varies greatly. The bodies of the perithecia arrange 
themselves compactly forming the base of a stroma. 
The perithecial wall is gray or black and sometimes light brownish black 
in color under a microscope. But when seen under a hand-lens or with the 
naked eye, the perithecial wall appears jet black. The mature perithecia 
measure about 350-580//. in diameter and are mostly spherical, but the shape 
is often modified by the pressure of the adjoining perithecia. 
Since the perithecia are always in the bottom of the stroma, or even 
partly in the host tissue, the length of the neck varies with the luxuriance of 
the stroma; but, in general, it is 1.5-3 times the diameter of the body. In a 
microtome section the wall of the perithecia on artificial cultures is seen to 
be composed of eight or ten layers of thick-walled cells. Inside these, there 
are a few layers of thin-walled cells, from the inner surface of the basal part 
of which the asci grow out into the cavity. But the wall of the neck is 
composed of densely interwoven, septate, thick-walled hyphae running longi- 
tudinally, parallel with the long axis of the neck. 
The hyphal branches, or periphyses, project out free into the canal and 
they are especially prominent at the swallen tip of the neck where the canal 
is also enlarged (PI. X, Fig. 9.). 
d. Asci and Ascospores. 
When mature the cavity of the perithecium is filled with asci, each con- 
taining eight allantoid spores. The asci are formed from the base of the 
