re now working along this line and we hope,
for valuable results before long.

The origin of the disease, as already stated, is something of a mystery,
and there is as yet no generally accepted theory, although many people
have very pronounced views on the subject. Many puzzling facts have been
noted since investigating the disease in Pennsylvania, among them being
the large percentage of infection in eastern York and southern Lancaster
counties, the relative small percentage in certain localities around
which the blight is generally prevalent, and recent infections found in
Warren and other western counties, a great distance from what is known
as the western advance line of the disease.

Our pathologists have reported some very interesting facts in regard to
the dissemination of the blight. In the preliminary report of the
summer's work at our field laboratories the results tend to show:

First, the prolific ascospore stage is very important in causing the
spread of the blight, the spores at this stage being forcibly ejected
from the pustules and borne through the air for some distance. This
ejection of spores takes place under natural field conditions only when
the bark has been soaked by rain, but the expulsion of spores is also
dependent upon temperature conditions and ceases entirely at
temperatures from 42 to 46 degrees F. and below.

Second, the wind plays a large part in local ascospore dissemination.

Third, birds and insects (except ants) are apparently of very little
importance in the dissemination of the blight except in providing
wounds. Further investigations of the importance of ants is being made
during the present winter.

Several kinds of beetles have been observed eating the pustules and are
in this way beneficial, since tests show that they digest and destroy
the spores. It has also been suggested by workers in the Bureau of
Entomology that such beetles, which are of several kinds, may be of
value in the attempt to control the disease. These are perhaps the only
natural enemies discovered to date.

The proper classification of the chestnut blight fungus has also been
the subject of much discussion. Last winter specimens of what in
external characteristics appeared to be Diaporthe parasitica were found
in western Pennsylvania, Virginia and elsewhere, growing upon chestnut,
oak and other species. This condition was puzzling and the subject of
some controversy. It has been found, however, that th