406 
Journal of Agricultural Research 
Vol. II, No. 6 
minute summer spores emerge from day to day in elongated reddish 
brown masses to be disseminated by the wind and other agencies, such 
as insects, birds, squirrels, etc.” The same author also says (13) “every 
bird and insect that rests upon an infected spot is liable to carry the 
spores upon its feet or body to other trees.” A few years later Mickle- 
borough (12) mentions birds as carriers of spores of the blight fungus. 
He says “the minute spores are carried by wind, on the feathers of birds, 
and the fur of squirrels.” Still later Metcalf and Collins (11) say that 
“ there is strong evidence that the spores are spread extensively by birds, 
especially woodpeckers.” Various writers have mentioned the fact that 
woodpeckers frequent chestnut trees in search of insects. Fulton (2) 
states in a report on field work done at Orbisonia, Pa., by Mr. R. C. Wal¬ 
ton that “woodpecker work was noted in about one-tenth of the oldest 
lesions,” but he offers no conjecture as to the part played by birds in 
the dissemination of the disease. 
Stewart (14) says that “undoubtedly the spores are carried long dis¬ 
tances by birds, especially woodpeckers, which visit the diseased trees, 
seeking borers, in the tunnels of which most of the infections occur.” 
This statement is based on the report of Metcalf and Collins previously 
referred to and is discredited by Fisher (1), who brings out the point that 
this and similar statements are not based on positive evidence. 
Kittredge (9) reports that field observations at Petersham, Mass., 
indicate “that birds may be a very important, if not the primary 
agent,” in the distribution of the blight fungus. He is led to this con¬ 
clusion from the greater number of infections near the borders of conifer¬ 
ous woods, where, he says, birds are more abundant, and from the much 
larger number of lesions in the middle third of the trunk, which he 
attributes to the work of creepers, nuthatches, and woodpeckers. 
There are numerous popular articles which also accuse birds of being 
instrumental in the spread of the blight, but these, as well as the state¬ 
ments already quoted, are based entirely on circumstantial evidence. 
The first serious attempt to determine whether birds actually do 
carry the spores of the chestnut-blight fungus was made by the field 
pathologists of the Pennsylvania Chestnut Tree Blight Commission 
during the summer of 1912. Since only negative results were obtained, 
it may be well to quote their statement giving the method employed: 
Birds found on the infected parts of trees were shot during the summer, and their 
feet, bills, and tail feathers washed separately in sterile water. This water was then 
centrifuged to bring down the spores that might have been washed from the birds. 
Part of the sediment was then examined under the microscope and the other part 
plated out in dilution plates. When colonies of fungi appeared, they were isolated to 
determine whether they were Diaporthe. 
The above description is not sufficiently detailed to make possible an 
accurate judgment as to whether the negative results obtained were due to 
