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ON A NEW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc. 
black point at the center of the surface of the stroma. 
Such a stroma is said to be "ectostroma" by -Ruiilan"d(i9Dd) 24) , separating 
it from "entostroma", in which perithecia are produced. The color varies 
with age, being white or light greenish black at first, later becoming grayish 
black or light blackish brown, finally greenish brown or black and sometimes 
lighter-colored near the center. The size of such "ectostroma" varies also 
with external conditions, and generally in moist situations they seem to 
develop much larger than in drier places. The stromata formed on the large 
branches are also much larger than those on the twigs. The matured ecto- 
stromata are usually elongated horizontally and their average size is about 
2.2 mm. in breadth, 1.5 mm. in height and 1.0 mm. in depth. 
In autumn the entostroma is produced under the ectostroma on the old 
canker, increases its size displacing the ectostroma, and at last takes posses- 
sion of its site completely. Of course it is not infrequently happens that the 
entostroma is independently produced without any connection with the ecto- 
stroma. 
In the formation of the entostroma, the initial stage of its development 
is exactly the same as in the case of the ectostroma. It is also elongated 
horizontally and has a conical or wart-like shape, having a round or elliptical 
base. Its average size is about 3-5 mm. in breadth, 2-4 mm. in height and 
1-1.5 mm - in depth. The entostromata also vary widely in size with the 
environment and season ; they become much larger in moist situations than 
in dry surroundings. The color also varies with age, being brownish gray 
at first, later becoming gray or light black on the surface, but always gray or 
yellowish gray near the center. The stromata are subcoriaceous and easily 
torn apart. 
The matured entostroma has on the exposed surface numerous minute 
black papillae which project scarcely above its surface. On a single stroma 
from only a few to thirty or more of these papillae may be found. Kach 
papilla is the opening of a long neck that forms a canal from the perithecium 
buried in the stroma. 
