To the Editor.—In essence Dr. Schwarzbart believes, as accepted in the past, that the middle ear is lined by flat endothelium and does not bear cilia nor is it capable of secreting mucus. In Dr. Schwarzbart's paper1 he states that the same is also true for the bony part of the eustachian tube. However, facts are stronger than theories: thus histologic and histochemical studies, documented photomicroscopically, show the middle ear to bear cilia and produce mucus in the normal state2-4 like every mucosa does. This was shown also in in vivo observations5 and explains the reaction of this mucosa under pathological conditions as well.6,7