98 
EASTERN SHADE TREE CONFERENCE 
We have every possible proof that our hybrid chestnuts are true hybrids 
and we find in many cases that they demonstrate hybrid vigor not only 
in vigorous vegetative growth but also in sexual precocity. Our particu¬ 
lar object here is of course to develop a chestnut which shall replace our 
practically extinct American timber species and at the same time be 
blight resistant. In our first crosses of the Japanese and American, the 
former being disease-resistant but a comparatively low-growing tree, the 
hybrids show remarkable vigor, but even the best individuals are not as 
resistant to the dread chestnut blight fungus as is the Japanese parent, 
(slides) We are therefore now crossing these Japanese-American 
parents (which have bloomed at an early age) with Chinese chestnuts, 
which we have proved by testing with inoculation of the fungus to be 
entirely resistant. This is only one of the lines we are following in the 
effort to eventually develop a timber type of chestnut which shall be 
disease-resistant. In our plantations at Hamden, Conn., we have from 
the beginning tried to assemble all the species of chestnut in the world, 
and we now have all except three Chinese chinquapin species growing. 
Having them growing in close proximity makes the work of crossing 
easier. To date we have produced by hybridization nearly 50 different 
new types of chestnut trees (slide). 
Possibly the selection of particularly promising individuals of a 
species and their vegetative propagation by cuttings, or in some other 
way, may be said to come under the head of breeding, if we use the term 
in a very broad sense. It does not involve the mingling of the proto¬ 
plasm of two parents. It consists merely of establishing a race of 
individuals, all essentially alike since they are derived from an individual 
and constitute therefore what is known as a cion. 
A few days ago I received a letter from Dr. R. Kent Beattie, Principal 
Pathologist of the Division of Forest Pathology of the U. S. D. A., telling 
of the work done along this line by the Dutch. He says: “I may say 
that in my visit I made to the Netherlands where I spent a number of days 
going over their work, I was convinced that the Dutch are doing very excel¬ 
lent work along the line of attempting to produce a European elm 
resistant to the Dutch elm disease. The method they are using is to 
search the European elm population for resistant individuals and then to 
multiply the resistant ones by propagation until they have determined 
their resistance. Of the 500 or 600 elms, which they brought from 
Madrid, Spain, in the year 1929, only one individual turned out to be 
resistant to the disease. It has been very greatly multiplied and many 
