ENDOTHIA CANKER OF CHESTNUT 587 
most trees with cankers above are also diseased about the base. Also, 
ascospores, which sometimes ooze out instead of being forcibly ejected, 
may be carried down in this manner. It was proved by a large number 
of inoculation experiments that either ascospores or pycnospores suspended 
in water in this manner and introduced into wounds will produce a high 
percentage of cankers (Tables 1 and 2, page 571). 
In another set of experiments, wounds were made beneath cankers 
on which there were only spore horns. The cankers were sprayed with 
an atomizer and the water containing the spores was allowed to run 
down into the wounds. Of twenty-three wounds treated in this way, 
sixteen developed cankers-later. There is no doubt, then, that rain is 
an important agent in spreading the spores to different parts of the same 
tree. Rain also plays an important part in bringing about the conditions 
necessary for the ejection of ascospores. 
Birds 
It seems reasonable to believe that birds alighting on cankers and picking 
at them carry spores to other trees and deposit them in wounds where 
they may germinate and produce cankers. Anderson and Babcock 
(1913) shot birds during the summer, but no spores could be isolated 
from them. Heald and Studhalter (1913) tested the washings from 
thirty-six birds of nine different species, all of which were shot on diseased 
parts of trees between February and May. Downy woodpeckers, 
nuthatches, golden-crowned kinglets, sapsuckers, brown creepers, and 
juncos were found to carry enormous numbers of pycnospores, the smallest 
number per bird being 5655 and the largest 757,074. No ascospores 
were found on the birds. B 
There can be little doubt that birds aid in the dissemination of the 
fungus. 
Wind 
Unlike the agents mentioned heretofore, the wind as a disseminator 
has to do mostly with ascospores. In a number of the earlier contributions 
to the literature it is stated that the summer spores are blown about 
by the wind; but this belief was gradually abandoned when it was pointed 
out that the spore horns are so hard when dry that they cannot be broken 
even by a strong blast, and when wet they are of a sticky nature and can 
hardly be detached by the wind. Metcalf (1913:366), however, still 
believes that under certain conditions they may be carried by the wind, 
for he says: 
“Tt is conceivable that they may be blown by the wind as far as rain 
or spray is blown or, mingling with the dust at the foot of the tree, be 
blown about with the dust.” 
