of the bark; such as extensive development of the
callus tissue, and the presence of a peculiar substance or white
secretion which is particularly conspicuous in cases of marked
resistance.

IS THE DISEASE RESISTANCE HERE AN HEREDITARY CHARACTER?

As to whether this disease resistance is an inherent character and will
be transmitted from generation to generation, or is only the result of
particularly favorable environmental conditions such as soil, light or
moisture, is a point of great practical importance. I believe that
further work will prove that the resistance is heritable, for the
following reasons:

1. The resistance is not due to a particularly favorable environment of
the trees, for the three groups grow in very different soils and under
varying conditions of light and moisture.

2. The finding of the trees in colonies points to a genetic variation.
At first I was unable to account for the grouping of the trees, for I
had expected to find immune or resistant trees singly, here and there.
But if we adopt the hypothesis of a heritable protoplasmic
variation--something in their "blood," so to speak, the explanation is
easy. We know that chestnut fruits or nuts do not travel far, like the
seeds of willow, poplar, maple or ash, and therefore, in any given stand
of chestnut, if we could go back from generation to generation into
earlier time, most probably the majority of the trees would be found to
have arisen from a common ancestor, although of course a few outsiders
would have found their way into the group, carried by squirrels or other
animals.

3. In a considerable number of cases all the members of the same group
of coppice trunks from an old stump show a similar degree of resistance.
To attribute such a condition as due merely to chance, occurring as
often as it does, would be placing a pretty large burden on chance; and
since the coppice trunks are all off-shoots of the same plant, the
condition is what one would expect were the resistant quality in
inherent character. A correspondence of degree of resistance was also
noted, in the inoculations made on branches, trunk, and basal shoots of
the same individual tree.

Experimental work is being carried on at Washington to test out the
truth of this hypothesis, i. e. to see whether or not the disease
resistance is really heritable. The work is being carried on in
connection with the propagation of other resistant stock, Chinese,
Japanese, etc.; and,