9. THE MAUTHNER CELL
321
Sc'h
Fin. 35. Connection between swim bladder and labyrinth by the Weberian
ossicles in Osturiophysi: Black, Weberian ossicles; Sch, swim bladder; Si, sinus impar
( perilymphatic space); C tr, canalis transversus (endolymphatic space); S, sacculus;
L, lagena; U, utriculus; H, brain (posterior part being removed); I, incus; St,
stapes; and M, malleus. From von Frisch (1936).
of both sides. Furthermore, even without the intermediation of the
swim bladder, a vibrational stimulus in the environment located symmetrically with respect to the two vestibular systems would be expected to affect them more or less equally and synchronously. Here then,
are two situations which make it likely that the Mauthner cells could
often be excited simultaneously, an event, as we have seen, which would
be singularly unproductive of the powerful tail flip caused by the excitation of a single Mauthner cell. Before dealing with this apparently
unpromising situation, let us consider the asymmetrically effective
stimulus.