20/ 8 ON A NEW CANKER DISEASE OF PRUNUS YEDOENSIS, etc. 
Experiments I. 
It is rather difficult in making a series of inoculations in the field to 
provide conditions which correspond to those of natural infection, and also 
by such experiments to draw the conclusion that the disease is caused by the 
fungus used. 
From April to June, 19 14, I inoculated the fungus on Prunus yedoensis, 
using various methods in the field. But all these inoculations resulted in 
failure with one exception, that is, when I inoculated with the germinating 
ascospores in the apple juice into a wound and covered it up with moist cotton 
and paraffine paper for a few days. After two months I found the character- 
istic appearance of the disease around the inoculated point. The failures of 
other inoculations were due chiefly to the want of moisture or to the washing 
away of the spores by a heavy rain. 
Experiments II. 
In this case, the seedling trees of Prunns yedoensis, a little more than two 
years old, grown in pots, were used. In July, 1914, the inoculations were 
made partly with pycnospores from artificial cultures, and partly with asco- 
spores from a natural host. Ordinarily, a small slit in the bark was made with 
a sharp sterilized scalpel, and the spores were introduced with a sterilized 
needle. The wound was covered with moist absorbent cotton, and then all 
was bound up with paraffine paper. The seedlings, inoculated by the same 
method, were partly placed in a moist condition under a bell-glass for a few 
days. As checks, uninjured sound bark and lenticels were also inoculated. 
Although in all these experiments the moisture was supplied in sufficient 
quantity, in no case was the infection accomplished. 
Experiments III. 
Again in September (28-30), 19 14, the seedlings of Prunus yedoensis, 
a little more than two years old, grown in pots, were used for inoculation. 
In these experiments, for the place of inoculation, a small portion of the bark 
