=The First Stage.=—The active pathology is limited to the pharyngeal portion of the Eustachian tube with some inflammation of the membranes of the tympanic cavity. Closure of the tube followed by absorption of the oxygen causes a decreased pressure in the tympanic cavity and thus a retraction of the drum, decreased movement of the ossicles and a general decrease in function of all tympanic structures. Deafness in this stage may be very marked, especially if the Eustachian occlusion has occurred from some nasopharyngeal acute inflammation. There may be pain but there is always a characteristic “fullness” and sometimes dizziness. Deafness in these cases varies with weather changes. If proper treatment is had in time, the progress of the pathology can be stopped and every case can be restored to normal hearing. =The Second Stage.=—The active pathology has extended throughout the Eustachian tube causing marked occlusion and some stenosis. There is further inflammation of the tympanic structures with an increase in the symptoms of the first stage. The drum membrane is less movable but there is no fixation of the ossicles. Pressure upon the bulb of the auroscope causes movement of that part of the drum to which the malleus is attached. The drum is thicker, more retracted, and less movable than in the first stage. Presbyacusia is common and often marked, but there is no paracousis. More than 90% of these cases can be materially improved and many can be made to hear normally if proper treatment is given in due time. =The Third Stage.=—The active pathology in the third stage consists of an involvement of the entire mucous membrane lining the Eustachian tube and tympanic cavity. These membranes are all chronically hypertrophied. The Eustachian tube, however, is sometimes fairly well open, but the ossicular attachments are more or less fixed by hypertrophied tissue and adhesions and the drum is markedly retracted, thickened and usually very immovable. The deafness is usually quite marked, head noises are commonly present and often very annoying. Patients usually do not notice a variation in their hearing from weather changes. Presbyacusia is present in 80% of cases and their hearing for low tones is much reduced. Unless there is a complicating nerve affection these cases hear well by telephone, which means that they can also use an electric hearing instrument to advantage. These cases can never be restored to normal hearing, but many of them (30% of my cases) can have some improvement and in most cases I believe the progress of the pathology can be stopped, and this is always well worth while because their hearing is likely to be entirely lost if something is not done.