EAR Operations on the Temporal Bone carried out with the help of the Lens and the Microscope. GUNNAR HOLMGREN. (Ada Otolaryngologica, Vol. iv., fasc. 4.) Owing to the small dimensions of such middle-ear structures as the stapes, fenestrae, etc., it is impossible without the help of optical magnification to obtain the precision and security desirable in radical operations involving the tympanic cavity. For more than a year, therefore, the author, in performing the radical mastoid operation, has

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... ade use of a binocular lens with magnification of two diameters. The instrument is that devised by the ophthalmologist, Gullstrand, and is worn like a pair of spectacles, giving a stereoscopic picture at a distance of 25 cm. To use the instrument correctly some practice is required; a good light, such as that from a Nernst lamp, concentrated by a lens and reflected into the wound is also essential. In order to attain a greater magnification a Zeiss binocular microscope has been used, with a magnification of nine diameters, a still higher power being sometimes employed. Small and delicate instruments have also been devised for operating under these conditions. By the help of the microscope the mucoperiosteum of the tympanic cavity can be completely removed, carious bone can be eradicated from dangerous situations with precision and safety, the tensor tympani muscle and processus cochleariformis can be removed with ease, and the mobility of the stapes and of the membrane of the fenestra rotunda estimated with certainty. The microscope, besides, renders possible the exact performance of various delicate operations which have been suggested and occasionally practised in cases of chronic obstructive deafness, such as the removal of cicatricial tissue from the inner tympanic wall and the establishment of artificial fenestrae.