290 ON A NEW CANKER-DISEASE OF PRUNUS VEDOENSIS. etc 
nuclei pass out into the germ tubes almost as soon as they start. The wall, 
also, has increased in thickness until it almost equals the diameter of the 
resting spore." This is surely a very interesting observation, but I can not 
yet assert whether it is correct or not, at least in the case of the present 
fungus. 
b. Germination of Ascospores. 
Unlike the pycnospores, the ascospores germinate readily in pure water. 
After two or three days, the germinating hyphae grow weaker and weaker, and 
at last die in water. The time required for germination is much shorter 
than for the pycnospores in a nutritient solution or even in pure water. At 
comparatively low temperatures, ranging from 14 0 to 24°C, it occurs perfectly- 
within the first twenty hours. I even observed the septation and branching of 
the germ tube at the end of twenty-four hours. From such facts, we can 
safely infer that if they are placed under more favorable circumstances, germi- ; 
nation will take place within six or twelve hours, and that therefore infection 
by the ascospore is most considerable and dangerous. 
Like the pycnospores, the ascospores swell before germination, but not 
to so great an extent as in the case of the former. The ascospores, measur- 
ing 16.O-22.0 x 3.2— 4.8 n at first, were found, just before germination in a 
bark decoction and pear juice, to measure 20.0-36.0x4.0-10.0//. But 
according to my observations, they always swell uniformly, keeping their 
original allantoid form. This character differs from that of Valsa leucostoma 
in which Aderhold (1903) 0 observed the spores to swell to ellipsoidal or 
globular shape. The first germ-tube usually appears at one end ; the next 
one comes from the other end or from one side ; and these are occasionally 
followed by another one or two, making a total of one to four germ tubes. 
They are most commonly thrown out from both ends, but rarely from the 
convex side of a spore. About tO% to 1 5 % of the germinating ascospores are 
divided into two cells as in the case of the pycnospores (PI. X, Fig. 1-2.). 
In 1891, such two-celled ascospores before germination were already observed 
