Ever since Bárány1 first observed that opening of the external semicircular canal improved hearing in clinical otosclerosis, the pioneers interested in the evolutionary development of the fenestration operation realized that to make the procedure entirely successful they would have to find definitely prescribed means for preventing postoperative osteogenetic closure of the newly created fenestra if the improved hearing was to be maintained permanently. It became obvious, also, that prevention of postoperative inflammatory reaction of the vestibular and the cochlear labyrinth was a necessity, since such inflammation, when severe enough, could not only interfere with maintenance of the immediate hearing improvement obtained by opening the perilymph space of the vestibular labyrinth, but might also result in still further impairment of hearing.
After experimental trial with monkeys and the adoption of changes in my techniques, I succeeded in devising and prescribing a logical means for consistently preventing the osteogenetic closure of