ies which, by natural selection and adaptation have fitted
themselves to the environment are, as a rule, the trees which will do
best in that locality. That is a principle I think which ought to be
thoroughly well fixed in mind. One may experiment with any number of
trees from a distance, but the trees which naturally have adapted
themselves to a locality, the species which have done that are the
species upon which we can expend our efforts to the best advantage.

In the matter of chestnut blight, we assume that the chestnut blight
will act like measles blight, scarlet fever blight, or any other
epidemic. In other words, it is due to a microbe, it is due to a
peculiar microbic group, a peculiar family group which happened to
start out in northern China on its invasion and got to this country
where it found trees which were not resistant. The American and European
trees are not resistant. Wherever it has gone from northern China, from
the place where blight, the tree host and enemy grew up side by side,
and represented the survival of the fittest; wherever it has gone away
from the place where we have the survival of the fittest, at any rate as
a result of struggle, there it has found susceptible individuals that it
has destroyed. When a blight of any sort sets out, chestnut blight,
measles, scarlet fever--any blight you please, you are talking natural
history, you are taking biology, about an animal or a plant, about a
microbe, a living thing. All of these living things run out of their
vital energy in time. Each microbe runs out of its energy just as a
breed of horses or of strawberries runs out of its energy. All
varieties, varietal types, run out of their natural energy, so that it
is simply a question of length of time before this family microbe or
family group of this microbe will lose its energy. We do not know how
many years that will be. It may be a great many years, and by that time,
our chestnuts may practically have disappeared. We can find here and
there a tree which resists better than others do, and we may find some
with enough resistance to be worthy of propagation as of that resistant
kind. We know that several species resist the blight very well. I found
four species that resist the blight very well among six kinds I have
tried out on my place. But some chestnuts bear so early and heavily that
we may afford to set them out, even in the presence of blight, trimming
them back and looking after them careful