REMEMBER THE CHESTNUT—ULM 
in the pin-point pustules. Extremely 
small, it was easily blown by the wind 
to infect new trees. The second was 
contained in sticky yellow ribbons 
extruded from the pustules more or 
less as toothpaste is extruded from a 
tube. These were called pycnospores. 
Being moist, they adhered to the feet 
and bodies of wild animals, and were 
thus carried considerable distances to 
other chestnut trees. 
This apparent ability of the blight 
fungus to spread under any conditions 
played right into the hands of oppo- 
nents of the “immune belt’? theory, 
who could see no purpose in putting 
thousands of dollars into what they 
believed was a lost cause. The result 
was that 2 years later the Chestnut 
Tree Blight Commission ceased con- 
trol work. Hastening its demise was 
the failure of a number of other States 
to cooperate. Later experience has 
shown that the blight can be kept out 
of certain localities, and there is reason 
to believe that elimination of trees in 
advance of the main progress of the 
fungus in Pennsylvania deterred the 
blight by at least 5 years. 
From 1913 on, with practically no 
human opposition, the blight spores 
continued to be carried southward and 
westward. 
The severity of the disease made it 
clear to most investigators that this 
was no mere flare-up of an indigenous 
parasite, though a few maintained the 
pathogen to be a curious mutation of 
a heretofore harmless fungus. Others 
believed it had come from European 
trees imported to this country. In the 
80’s and 90’s of the last century there 
had been a great wave of interest in 
commercial chestnut orchards, and 
large numbers of chestnut trees were 
brought in from Europe by nursery- 
men. 
When a fungus, claimed by a num- 
ber of experts to be identical with the 
organism causing blight on our native 
trees, was found on these European 
chestnuts, the mystery appeared 
solved. The reasoning was that this 
fungus, termed Endothia  radicalis, 
379 
though apparently harmless to the 
European chestnut, was deadly to 
ours. This plausible hypothesis, how- 
ever, was exploded when it was shown 
that the European tree, when attacked 
in this country by the fungus from one 
of our blighted native chestnuts, also 
withered and died. Eventually, the 
two fungi were found to be different, 
though related. The blight-causing 
fungus, Endothia parasitica, was virulent 
and definitely fatal in effect. The 
other was innocuous and attacked only 
dead tissue. 
With Europe eliminated as a source 
of blight, scientists began to look else- 
where, notably to the Asiatic coun- 
tries. They began with the Japanese 
chestnut trees that had been brought 
into this country in the latter part of 
the nineteenth century, and it was 
soon observed that some contained 
cankers indicating infection from 
blight. The Japanese tree often sur- 
vived, however. It was this resistance 
that gave investigators Haven Met- 
calf and C. L. Shear the clue they 
were looking for. Both scientists had 
become convinced the blight had en- 
tered this country from the Orient— 
but they needed proof. 
Dr. Shear’s first act was to send 
a specimen of diseased chestnut bark 
to Frank Meyer, the famous plant 
explorer, then in China, who agreed 
to search for comparative evidence 
of blight in that country. 
The American researchers did not 
have long to wait. Within a short 
time Meyer wired that he had found 
evidence of what he believed to be 
blight. Three weeks later the De- 
partment of Agriculture received a 
specimen of bark from a Chinese 
chestnut which Meyer had located in 
northern China. Metcalf immedi- 
ately examined the material and re- 
ported, “It looks like it.””_ Then Shear 
found the characteristic ascospores in 
cultures made from the bark. Later 
the scientist inoculated trees in this 
country. 
Thus, in less than 3 months, it was 
definitely established that the chestnut 
