IZ 
and the remainder, about 225, were shipped to the Division of 
Forest Pathology at Beltsville, Maryland, where they are to be 
set out in a good location. The 50 trees that | have kept will 
be tested for disease resistance by the inoculation method, and 
the most resistant will be used for further breeding. 
American Seedlings —About 300 one- and two-vear-old seed- 
lings of American chestnut were set out in another nursery. 
These were grown from nuts received from various places i in the 
Eastern States (see reports for 1941 and 1942). This winter 
these seedlings were covered with brush, an apparently effective 
way of preventing rabbits from shearing them off. The hybrid 
seedlings of 1942 were protected from rabbits by a fence of wire 
netting, and from pine mice by a border of wire netting sunk one 
foot deep in the ground. 
Inoculations for Testing Disease Reststance.—In cooperation 
with the Division of Forest Pathology, U.S.D.A., we started dur- 
ing the summer another series of inoculations—about 250 in all, 
to test the disease resistance of our hybrids. A detailed report 
of this work must be postponed for the present. 
Studies of Disease Resistance—The ultimate cause of blight 
resistance in some species and individuals and of susceptibility 
in others has never been determined. It appears quite likely that 
it is related to the relative degrees of sap concentrations in the 
cells of the host and parasite. This hypothesis is not new, but 
was put forward by Dr. A. P. Kelley, of Landenberg, Penna., in 
Science for March 22, 1940. With the cordial cooperation of Dr. 
EK. W. Sinnott and the staff members of the Osborne Botanical 
Laboratory at Yale University | spent some time at the laboratory 
during the summer in studying this problem. The work will be 
continued in 1944 
Cooperative Plantations.—The plantation of Chinese and Chi- 
nese hybrids at Litchfield on land of the White Memorial Founda- 
tion was visited several times during the summer, and now, thanks 
to the interest and cooperation of Mr. Clifford Ongley, super- 
intendent, the plantation is in a thrifty condition. Our chief 
enemy has been the deer, but the details of the situation will be 
presented in a later report.—In the plantation of hybrids on land 
of Mr. Archer M. Huntington at Redding Ridge, Conn., which 
