Elm-Trees are frequently subject to a kind of ulcers ; which, if not timely attended to, eventually destroy them. Such as are planted in marshy grounds, or in the vicinity of rivers, are chiefly liable to this distemper : the ulcer generally appears on the side exposed to the south, and at a little, distance from the root; though it sometimes occurs five or six feet above the surface.
The cause of this disease was, by Du Hamel, supposed to be a superabundance of sap; which conjecture has lately been corroborated by the experience of M. BouR-chier. In order to cure the trees thus attacked, the latter pierced the ulcer with an auger, and after wards fitted to the hole a tube that penetrated to a sufficient depth. He observes from experience, that the trees thus affected, yield a larger proportion of sap in serene than in tempestuous weather ; and accordingly as the wound is more or less in a southern exposure : after two or three days, the sap-flow ceases, and the wounded part spontaneously heals.