This is the most popular topic in the agricultural papers just now. We see no reason for doubting the conclusions of Dr. J. Gibbons Hunt, the accomplished president of the Microscopical Section of the Academy of Natural Sciences, of Philadelphia, who, after a careful microscopical examination of fresh-specimens, decided that it was caused by a small fungus working from the outside of the wood inwardly, as we have already detailed in the Gardener's Monthly. Dr. Leighton, of Norfolk, Virginia, has in a measure confirmed these facts, by showing that pear blighted trees had perfectly healthy roots, no fungus about them; so it is not likely fungoid material was carried up in the liquids, and so worked from the interior as they do in the peach yellows.