The operation of opening the mastoid process is said by some to have been first performed by Riolan in 1649; according to others, by Petit in 1750, and later by Jasser, in 1776. During the latter part of the eighteenth century the operation was performed frequently without definite pathological indications. But after the unfortunate death of the Danish physician Berger (1791) the operation was very seldom or never performed until 1864, by Mayer, following the suggestions made by Tröltsch some years previous. Berger, for chronic deafness without suppuration of the middle ear, had the operation performed upon himself, and died on the twelfth day from meningitis. During the past twenty years the operation has taken its place as one of the recognized surgical proceedings owing to the work of the German physicians Moos, Jacobi, Hartman, Bezold, Schwartz and others, who have laid down the real indications for the operation from their extensive clinical observations and pathological researches. The American otologists, Roosa, Agnew, Buck and others were among the very first to perform the operation, and have done much to establish its claim to recognition. And yet it is somewhat remarkable that some of our text books barely mention the operation; and as short a time ago as 1883, Strawbridge, at the meeting of the American Otological Society, said that he had seen over four thousand cases of purulent middle ear disease within twelve years, and yet had not trephined in a single case; and several other authorities looked upon the operation as a questionable one. Knapp took decided grounds in favor of the operation, and cited three fatal cases in which he believed an operation would have saved life. Kipp had seen quite a number of fatal cases in which the post-mortem had shown the mastoid cells filled with pus, which had given rise to cerebral abscess. Dr. C. H. Burnett reported a fatal case which died from pyemia, and he thought if his patient had been operated a year before his life would have been saved. Gruening said surgery has established that wherever there is a focus of purulent discharge it should be removed. This, (removal of the focus) is a life-saving operation and should be done under all circumstances. Dr. Roosa said that he believed the revival of this operation of opening the mastoid process has saved many lives. Since his first operation not a year has passed that he has not found it necessary to repeat it several times. He says further that "it is true that we shall seldom need to open the mastoid if an experienced practitioner sees a case of acute aural disease early in its course. It is an operation for neglected cases, where suppuration has been allowed to advance from the tympanic cavity in consequence of not having a free outlet through the drum-head. But purulent inflammation of the mastoid may occur in acute cases that have been thoroughly treated by leeching, poultices, rest, etc., from the start."