lse to make filbert culture unprofitable. We have practically
the same proposition in the walnut bacteriosis, not only in the
northeastern United States, but in the best walnut districts of
California. This bacterial disease which is undoubtedly a disease of our
native walnuts--probably the native black walnut--occurs rather rarely,
and so feebly developed as to be difficult to find at all on its native
host yet it becomes the great serious disease of the Old World
cultivated walnut.

Now, there again, it is not so much a lack of physiological
adaptability, because the walnut is thoroughly adapted to our Pacific
coast. I suppose most of you know that east of the Rocky Mountains, east
of the Great Plains, we have a humid climate and winters more or less
cold which corresponds, not with western Europe, not with Germany,
England, Spain, France and Italy, but with China and Japan, with Asia,
in its climatic conditions. The result is the Chinese and Japanese trees
brought to the eastern United States grow well but may grow
indifferently in California. On the other hand, the plants of the
Mediterranean, France, Germany, Italy and Spain do not, as a rule,
thrive when introduced into the eastern United States. There are a few
exceptions, like the apple and perhaps the peach. These are not really
natives of western Europe, but have been brought from the interior. They
are more like the Japanese and Chinese plants which came in by way of
Persia and which have been slowly adjusted to the conditions of western
Europe. That adjustment has gone so far that the Persian type of peach
does better on the Pacific coast than in the East. We are breeding a
race of these fruits from China, the Chinese cling group, which does
well in the eastern part of the United States, and we have from there a
peach that is better for the country east of the Rocky Mountains than
the ones that have been modified in Europe.

Now take the other side of this question, the foreign parasite--that is
very unfortunate thing--over which we do not always have the control
that we do with the foreign host. An equal disturbance of nature takes
place when we introduce a foreign parasite, whether it is from a similar
climatic region or one not so similar. The chestnut blight is a
tremendous example of that sort of thing. This has come into prominence
within a decade and it is one of the greatest problems in the pathology
of the chestnut. That has turned out to be a Chin