uts. They were just as good or better
than the American.

MR. CALDWELL: I spent about a year in China travelling pretty well
throughout the country. I believe you will find the better seed sources
in the southern part. China is like Southern Florida or warmer for part
of the year and yet in the other six months it would be colder than it
is right here in Rochester.

They have timber trees, some as big as 50 or 60 feet high and two or
three feet in diameter. In the warmer area you find better seed by far.
What Dr. Diller describes as No. 58602 is not just one tree, but a whole
collection of trees from a certain area where the trees have proven
their resistance not only to cold but to frost injury in the spring or
in the fall, which is even more important than the straight cold
hardiness. Some people have mistaken ideas about the value of seed from
trees in the northern part of China above the Great Wall. This area may
have intense cold in the wintertime, but not in the spring or fall.

DR. GRAVES: Dr. Caldwell is right about No. 58602 being a mixture. Dr.
Gravatt could tell you about that. It is a strain coming from several
trees. It's evidently a very fine type, and I think we ought to know for
the record just what 58602 is.

DR. GRAVATT: Professor Reisner's 58602 that Dr. Diller has been testing
so widely is made up from a collection of seed from a number of isolated
valleys of the Nanking area. It is rather southern in its native home,
but Dr. Diller's tests and other tests have shown that it's hardy up
north and it's hardy down south. As some of you have noticed, the nuts
are very variable, with a number of different types mixed in together.

Dr. Diller and I have been discussing the question of hybrid vigor. It
may be involved that each of these seedlings is a cross between
different local strains. We must remember that the foresters have gone
into this question of hardiness in great detail. You will find that you
can't plant trees in Germany in a certain area unless the parent trees
grew in a certain area, with comparable altitude and latitude. Minimum
and maximum temperatures and other factors are also taken into
consideration.

Pennsylvania started a program along the same line. They have divided
their state into about five areas, and in each of those areas they are
locating sources of seed that are going to be suited to those areas.
They have evidence that many of these Chinese introductions coming from
w