Attention may be drawn to this elaborate and systematic study by Professor Grasset, who is also publishing (in the Bibliothèque Scientifique Internationale) a volume entitled Maladies de l'Orientation et d'équilibre. The author, who shows a wide knowledge of the work on this subject done in other countries, considers it important to remember that vertigo is constituted of two sensations: (a) a sensation of displacement of the body in relation to surrounding objects; (b) a sensation of loss of equilibrium. He defines it (“synthetically and schematically”) as a “subjective psychic phenomenon constituted by the transmission to the cerebral centre of a double sensation: a false sensation coming from the apparatus of orientation, and a sensation of the inadequacy of the polygon (by which he means the ensemble of the automatic centre of orientation and equilibrium) to ensure equilibrium.’’ Physiological vertigos are taken into consideration, though the study is chiefly devoted to the pathological varieties, and the symptoms are classed as anæsthetical, hyperæsthetical, and paræsthetical. A full schematic table of the objective and subjective symptoms is presented.