ANOSMIA is lack of the sense of smell. This deficiency may he due to nasal obstruction or to disease of the nerves concerned in smelling. It is sometimes a.manifestation of hysteria. In the first category, the common cold in the head is the most usual cause. Other frequent causes are adenoids, deviated septum and inflammation of the nasal passages. Of nervous diseases caus ing anosmia brain tumours are the most frequent. Any nasal ob struction or brain lesion must be on both sides of the cortex in order completely to obliterate the sense of smell.