TAKEWO HEMMT 267 
In the systematic studies on the genus Valsa, a great importance is 
attached to the structure of the stroma especially at its basal portion. In the 
case of the present fungus there is no black boundary line, so called "Con- 
ceptaculum", between the stroma and the host-tissue. The presence of such 
a boundary line is the most essential character of the Subgenus Leucostoma, 
which was founded by Nitschke (1867) and accepted by many subsequent 
authors. But in the case of our fungus, the stroma is composed mostly of 
the mycelial tissue in which disintegrated cells of the host are more or less 
intermixed ; while stromata of many other species belonging to the Subgenus 
Eitvalsa consist mostly of the host tissues, especially at their basal portion. 
Some sections of the stromata in our fungus have an appearance as if the 
whole body of the stroma is composed entirely of mycelial tissue, and that 
there is a distinct boundary between the hyphal portion and host tissue. A 
careful observation, however, showed at once that the above mentioned 
appearance is caused by the compact arrangement of the numerous perithecia 
in a single stroma. We do not find here a black compact stratum or bounda- 
ry line, and moreover, the closer observations revealed the presence of the 
host tissue scattered deeply in the stroma, even in the portion above the bodies 
of the perithecia (PI. IX, Fig. 3, 5.). We can more easily see the relation of 
such structures of the stroma by means of microtome sections of the material 
imbedded in celloidin. 
b. Pycnidia and Pycnospores. 
On the smooth bark of the diseased twigs or the young cankers, especial- 
ly in summer, the cork layer is raised in numerous little pustules, from the 
apices of which slender, reddish, waxy curling threads may be frequently 
seen in moist weather. As already stated, such pustules are the ectostromata 
in which the pycnidia are produced. The pyenidium appears at first as only 
a small cavity in the young stroma. If a cross-section is made through the 
young stroma, a lighter colored portion, which is composed of a loose growth 
of white or slightly yellowish mycelium, is seen at first, which gradually 
