234
0. LOWENSTEIN
120 Hz (Fig. 11). At that time no reliable information on “hearing” in
elasmobranchs was available. Nevertheless, the experiments established
the fact that the labyrinth contained vibration-sensitive end organs.
Hearing without the power of fairly accurate localization of the source
of sound would appear to be of rather restricted value to an animal. However, experiments on Phoxinus by von Frisch and Dijkgraaf (1935), and
on Plzoxinus and Ameiurus by Reinhardt ( 1935), both under natural conditions and in the laboratory, showed that only relatively high intensity
sound offered at close range (10 and 20 cm) had a directive effect, and
this effect was not impaired by the operative elimination of the labyrinth,
the Weberian apparatus, and the lateral line organs. The authors therefore attributed this limited sound localization to the tactile sensitivity of
the skin. Kleerekoper and Chagnon (1954), using low frequency vibrations in relatively small tanks, observed that Semotilus atromaculatus
atromaculatus (Mitchill) orientated toward lines of highest intensity in a
complex pattern of standing waves and intensity gradients from one or
more sources. The authors make no statement as to the nature of the receptor organs involved in these reactions.
2. THE SEAT OF ACOUSTIC FUNCTION
There is no reason to doubt that in fishes, as in other vertebrates, the
inner ear is the chief organ concerned with hearing, and the work of von
Frisch and his pupils has yielded convincing evidence that, at least in
the Ostariophysi, the pars inferior of the labyrinth, viz., the sacculuslagena complex, is chiefly responsible for sound reception, whereas the
equilibrium function of the labyrinth resides in the pars superior, viz.,
utriculus and semicircular canals ( Lowenstein, 1932). The fact that the
sound-conducting structures, such as the Weberian apparatus and socalled acoustic windows in the cranium (von Frisch, 1938; Dijkgraaf,
1950), appear to be closely associated with the pars inferior in the
Ostariophysi makes this assumption still more cogent. In other fish, such
as the Clupeidae, the morphological situation is different. Here the swim
bladder-labyrinth connection clearly aims at the utriculus, and the question arises (de Burlet, 1935; Wohlfahrt, 1936) whether potentially all
otolith organs could take on an acoustic function, the decisive factor
being the exposure to or insulation from vibratory stimuli, differing from
case to case in accord with the morphological situation. That this may
in fact be so is strongly suggested by the results of the electrophysiological
experiments on the labyrinth of the elasmobranch Raia claavata (Lowenstein and Roberts, 1951 ) . In these experiments the propagated impulse
discharges in response to low-frequency vibratory stimulation (up to 120
0. LOWENSTEIN
120 Hz (Fig. 11). At that time no reliable information on “hearing” in
elasmobranchs was available. Nevertheless, the experiments established
the fact that the labyrinth contained vibration-sensitive end organs.
Hearing without the power of fairly accurate localization of the source
of sound would appear to be of rather restricted value to an animal. However, experiments on Phoxinus by von Frisch and Dijkgraaf (1935), and
on Plzoxinus and Ameiurus by Reinhardt ( 1935), both under natural conditions and in the laboratory, showed that only relatively high intensity
sound offered at close range (10 and 20 cm) had a directive effect, and
this effect was not impaired by the operative elimination of the labyrinth,
the Weberian apparatus, and the lateral line organs. The authors therefore attributed this limited sound localization to the tactile sensitivity of
the skin. Kleerekoper and Chagnon (1954), using low frequency vibrations in relatively small tanks, observed that Semotilus atromaculatus
atromaculatus (Mitchill) orientated toward lines of highest intensity in a
complex pattern of standing waves and intensity gradients from one or
more sources. The authors make no statement as to the nature of the receptor organs involved in these reactions.
2. THE SEAT OF ACOUSTIC FUNCTION
There is no reason to doubt that in fishes, as in other vertebrates, the
inner ear is the chief organ concerned with hearing, and the work of von
Frisch and his pupils has yielded convincing evidence that, at least in
the Ostariophysi, the pars inferior of the labyrinth, viz., the sacculuslagena complex, is chiefly responsible for sound reception, whereas the
equilibrium function of the labyrinth resides in the pars superior, viz.,
utriculus and semicircular canals ( Lowenstein, 1932). The fact that the
sound-conducting structures, such as the Weberian apparatus and socalled acoustic windows in the cranium (von Frisch, 1938; Dijkgraaf,
1950), appear to be closely associated with the pars inferior in the
Ostariophysi makes this assumption still more cogent. In other fish, such
as the Clupeidae, the morphological situation is different. Here the swim
bladder-labyrinth connection clearly aims at the utriculus, and the question arises (de Burlet, 1935; Wohlfahrt, 1936) whether potentially all
otolith organs could take on an acoustic function, the decisive factor
being the exposure to or insulation from vibratory stimuli, differing from
case to case in accord with the morphological situation. That this may
in fact be so is strongly suggested by the results of the electrophysiological
experiments on the labyrinth of the elasmobranch Raia claavata (Lowenstein and Roberts, 1951 ) . In these experiments the propagated impulse
discharges in response to low-frequency vibratory stimulation (up to 120