226
0. LOWENSTEIN
Furthermore, a macula neglecta is absent in Myxine. It appears therefore
that the vertical macula may resemble the sacculus macula of the elasmobranchs by having a dual function. The specialized hair cells in the vertical macula are dispersed among the rest and not confined to any specific
area of the macula.
Early speculations on the relationships between the disposition of these
maculae in space and the origin of the various postural reflexes of eyes
and limbs await reappraisal in the light of such new evidence. Here is
an important field for further research. One may, however, be justified
in assuming that the utriculus is generally the chief receptor for gravitational stimuli ( Lowenstein, 1932, 1936). There are exceptions. There is
evidence that in the herringlike bony fishes a part at least of the utriculus
rather than the sacculus may be the organ concerned with hearing
(Wohlfahrt, 1932, 1936) and it was shown that in the flatfish, Pleuronectes
platessa and Platessa flesus, the chief gravitational responses derive from
the sacculus with the possibility of participation by utriculus and/ or
lagena ( Schone, 1964).
Whereas von Frisch and Stetter (1932) believed that in the minnow,
Phoxinus h v i s L., both sacculus and lagena may function as sound receptors, there is definite evidence that in the bony fish, Gymnocymbus
tereutzii, and in the frogs, Rana sylvatica and Rana palusiris, the lagena
participates in the control of postural equilibrium (Schoen, 1950; MacNaughton and McNally, 1946). It is interesting to note that removal of
the lagena in these cases leads to instability in or near the normal position. The electrophysiological findings ( Lowenstein and Roberts, 1949)
point to a similar functional range for the lagena in the elasmobranchs.
In summary it may be said that the otolith organs respond to linear
accelerations in general. They are therefore all potential gravity receptors.
Besides this they may respond to linear translation, centrifugal stimuli,
and rotating linear vectors during constant speed and accelerated rotations and finally to oscillatory linear accelerations in the form of vibrational and acoustic stimulation.
Equilibrium in fishes is not controlled by the labyrinth alone. In the
absence of highly developed proprioceptor mechanisms, visual orientation takes a considerable share in the control of posture and movement.
This is supplemented by so-called dorsal-light reactions which manifest
themselves in a tendency of the animal to turn its dorsal side in the direction of the incidence of illumination. The collaboration of eye and
labyrinth in this field has been analyzed by von Holst and his collaborators
by means of most ingenious experimental methods (von Holst, 1950).
These investigations have made a significant contribution to the understanding of quantitative and qualitative aspects of otolith function.
0. LOWENSTEIN
Furthermore, a macula neglecta is absent in Myxine. It appears therefore
that the vertical macula may resemble the sacculus macula of the elasmobranchs by having a dual function. The specialized hair cells in the vertical macula are dispersed among the rest and not confined to any specific
area of the macula.
Early speculations on the relationships between the disposition of these
maculae in space and the origin of the various postural reflexes of eyes
and limbs await reappraisal in the light of such new evidence. Here is
an important field for further research. One may, however, be justified
in assuming that the utriculus is generally the chief receptor for gravitational stimuli ( Lowenstein, 1932, 1936). There are exceptions. There is
evidence that in the herringlike bony fishes a part at least of the utriculus
rather than the sacculus may be the organ concerned with hearing
(Wohlfahrt, 1932, 1936) and it was shown that in the flatfish, Pleuronectes
platessa and Platessa flesus, the chief gravitational responses derive from
the sacculus with the possibility of participation by utriculus and/ or
lagena ( Schone, 1964).
Whereas von Frisch and Stetter (1932) believed that in the minnow,
Phoxinus h v i s L., both sacculus and lagena may function as sound receptors, there is definite evidence that in the bony fish, Gymnocymbus
tereutzii, and in the frogs, Rana sylvatica and Rana palusiris, the lagena
participates in the control of postural equilibrium (Schoen, 1950; MacNaughton and McNally, 1946). It is interesting to note that removal of
the lagena in these cases leads to instability in or near the normal position. The electrophysiological findings ( Lowenstein and Roberts, 1949)
point to a similar functional range for the lagena in the elasmobranchs.
In summary it may be said that the otolith organs respond to linear
accelerations in general. They are therefore all potential gravity receptors.
Besides this they may respond to linear translation, centrifugal stimuli,
and rotating linear vectors during constant speed and accelerated rotations and finally to oscillatory linear accelerations in the form of vibrational and acoustic stimulation.
Equilibrium in fishes is not controlled by the labyrinth alone. In the
absence of highly developed proprioceptor mechanisms, visual orientation takes a considerable share in the control of posture and movement.
This is supplemented by so-called dorsal-light reactions which manifest
themselves in a tendency of the animal to turn its dorsal side in the direction of the incidence of illumination. The collaboration of eye and
labyrinth in this field has been analyzed by von Holst and his collaborators
by means of most ingenious experimental methods (von Holst, 1950).
These investigations have made a significant contribution to the understanding of quantitative and qualitative aspects of otolith function.