7. THE LABYRINTH
219
(Parker, 1908), and Gobius jozo (Werner, 1929), and finally in Phoxinus
phoxinus ( Lowenstein, 1932; von Frisch and Stetter, 1932), separate
functional elimination of parts of the otolith system showed that the utriculus is able to control the whole range of postural responses to positional
changes. These responses consist of lasting eye deviations and fin postures,
the compensatory significance of which is the same as that of the dynamic
effector responses to angular accelerations. Bilateral elimination of the
sacculus and lagena complex leaves the fish with its gravity responses
practically unimpaired, whereas the bilateral elimination of the utriculus
abolishes the whole range of known postural reflexes. The anatomical
subdivision of the labyrinth into a pars superior (utriculus and semicircular canals) and a pars inferior (sacculus and lagena) is therefore
physiologically significant. Often the separation of these two parts is considerable, e.g., in the minnow, Plzoxinus, only a narrow canal, the canalis
uticulo-saccularis joins them, while in Gobius jozo the two parts are
completely separated. Corresponding results were obtained in all other
vertebrate classes (Lowenstein, 1936), although there remained a suspicion that in some cases the lagena may participate in the control of
equilibrium [Schoen and von Holst (1950) in the fish, Gymnocymbus
ternetzii; MacNaughton and McNally (1946) in the frog].
The extension of the oscillographic analysis of impulse responses from
the semicircular canals to the less accessible otolith organs carried out
by Lowenstein and Roberts (1949) in the elasmobranch Raja clavutu
showed quite clearly that the utriculus macula does in fact respond to
positional changes in all directions and that it is thus potentially capable
of controlling the whole range of postural responses. Figure 6 shows a
single-unit response of the utriculus to a full-circle tilt about the horizontal longitudinal axis ( lateral tilt), The discharge frequency shows a
clear maximum near a position in which the labyrinth under observation
lies uppermost (side up), and a minimum near the spatially opposite
position (side down). A similar picture would be obtained during foreand-aft tilting about the horizontal transverse axis of the fish. Besides
units which have static discharge rates strictly corresponding with certain
spatial positions of the labyrinth (position receptors), there are other
end organs in the macula which react by a change in their discharge rate
to the change of position as such, irrespective of the direction of the
change, returning to a basic discharge rate whenever the head has come
to rest in a new position (out-of-position receptors).
It was found that the posterior third of the sacculus macula closely
adjoining the lagena also responds to positional changes and that it does
so in much the same way as the utriculus. The two structures therefore
overlap in range, which means that one of them could be considered to
219
(Parker, 1908), and Gobius jozo (Werner, 1929), and finally in Phoxinus
phoxinus ( Lowenstein, 1932; von Frisch and Stetter, 1932), separate
functional elimination of parts of the otolith system showed that the utriculus is able to control the whole range of postural responses to positional
changes. These responses consist of lasting eye deviations and fin postures,
the compensatory significance of which is the same as that of the dynamic
effector responses to angular accelerations. Bilateral elimination of the
sacculus and lagena complex leaves the fish with its gravity responses
practically unimpaired, whereas the bilateral elimination of the utriculus
abolishes the whole range of known postural reflexes. The anatomical
subdivision of the labyrinth into a pars superior (utriculus and semicircular canals) and a pars inferior (sacculus and lagena) is therefore
physiologically significant. Often the separation of these two parts is considerable, e.g., in the minnow, Plzoxinus, only a narrow canal, the canalis
uticulo-saccularis joins them, while in Gobius jozo the two parts are
completely separated. Corresponding results were obtained in all other
vertebrate classes (Lowenstein, 1936), although there remained a suspicion that in some cases the lagena may participate in the control of
equilibrium [Schoen and von Holst (1950) in the fish, Gymnocymbus
ternetzii; MacNaughton and McNally (1946) in the frog].
The extension of the oscillographic analysis of impulse responses from
the semicircular canals to the less accessible otolith organs carried out
by Lowenstein and Roberts (1949) in the elasmobranch Raja clavutu
showed quite clearly that the utriculus macula does in fact respond to
positional changes in all directions and that it is thus potentially capable
of controlling the whole range of postural responses. Figure 6 shows a
single-unit response of the utriculus to a full-circle tilt about the horizontal longitudinal axis ( lateral tilt), The discharge frequency shows a
clear maximum near a position in which the labyrinth under observation
lies uppermost (side up), and a minimum near the spatially opposite
position (side down). A similar picture would be obtained during foreand-aft tilting about the horizontal transverse axis of the fish. Besides
units which have static discharge rates strictly corresponding with certain
spatial positions of the labyrinth (position receptors), there are other
end organs in the macula which react by a change in their discharge rate
to the change of position as such, irrespective of the direction of the
change, returning to a basic discharge rate whenever the head has come
to rest in a new position (out-of-position receptors).
It was found that the posterior third of the sacculus macula closely
adjoining the lagena also responds to positional changes and that it does
so in much the same way as the utriculus. The two structures therefore
overlap in range, which means that one of them could be considered to