V - Some features of the action of the utricular maculæ (and of the associated action of the semicircular canals) of the frog

Abstract

As is well known, the operation of unilateral labyrinthectomy produces a persistent leaning of the head accompanied by spinal torque. Breuer (1875) once ventured to suggest that damage to the utriculus might be responsible for this effect. Subsequent work by many observers, e.g ., Laudenbach (1899), G. H. Parker (1908, 1909), Benjamins (1920), Maxwell (1920), Manning (1924), McNally and Tait (1925), Versteegh (1927), von Frisch and Stetter (1932), has tended to support this original conjecture. One of the main obstacles to certainty on the subject is the operative difficulty of reaching the utricular macula and of carrying out its uncomplicated ablation. Hitherto the clearest evidence on the matter is that of Versteegh (1927). In the rabbit he succeeded, without damaging other structures, in making a partial severance of the utricular nerve on one side. As a consequence the animal exhibited persistent “Kopfdrehung” towards the side of the operation. If damage to one utriculus causes spinal torque and head twist, the inference is that the utricular maculae, in keeping the head horizontal, are adapted to respond to the field of gravity.