62
JERALD J. BERNSTEIN
Bardach et al. (1967) were capable of eliciting responses in chemoreceptors. Therefore, fish may have more taste responses than the four
conventional ones formerly found in fresh- and saltwater fish. However,
we are dealing here with two systems: a system of free chemoreceptive
nerve endings which respond to taste stimulation on the fins of tomcod,
and a system of taste buds for chemoreception which are found in the
palatal organs or the barbel of carp or catfish. In fact, it has been found
that free chemosensitive nerve endings in the sea robin fin do not respond
to sugars and that spinally innervated chemoreceptors of sea robins
respond to a smaller variety of substances than do the spinally and
cranially innervated fins of the tomcod.
It is not yet clear whether or not different sapid substances react on
selective sites of the chemoreccptors of the tastc cmd organs of the fish.
It is obvious, however, that certain animals such as freshwater carp,
respond maximally to certain stimuli. The palatal nerves respond grossly
to sweet substances. On the other hand, the sea catfish barbel does not
respond at all to sugar substances. It also appears that there is conipctition for sites on the receptor organ and that the balances and synergistic
effects of different substances yield quantativc differences in electrophysiological patterns of dischargc.
E. Audition
In general the experiments on audition can be divided into three
classes. In one, behavioral end points are used to determine the acoustic
threshold of an animal. The second utilizes autonomic unconditioned
responses (heart rate) to obtain audiograms. The last approach is an
electrophysiological approach to the determination of the central nervous
system information used in the integration of acoustic stimuli. The bchavioral work has established that the pars inferior (the sacculus and
lagena) are the chief organs for sound perception in thr tclrost and
vestibular function resides in the pars superior (utriculus and semicircular canals). However, different parts of labyrinthine function have
not been exclusively isolated in the organ so far. In general, members
of the Ostariophysi have much better auditory discrimination than nonostariophysid fish. This is most probably because of thc morphological
connection between the swim bladder and the inner ear through thc
three pairs of Webcrian ossiclchs (Alexander, 1966; Enger, 1963; Healey,
1957; Kleerekoper and Roggcnkamp, 1959; Lowenstcin et al., 1968). Fish
have perceived some frcquencics up to 13,000 Hz, although in most species
the upper hearing limit lies around 5000-7000 Hz and is the approximate
JERALD J. BERNSTEIN
Bardach et al. (1967) were capable of eliciting responses in chemoreceptors. Therefore, fish may have more taste responses than the four
conventional ones formerly found in fresh- and saltwater fish. However,
we are dealing here with two systems: a system of free chemoreceptive
nerve endings which respond to taste stimulation on the fins of tomcod,
and a system of taste buds for chemoreception which are found in the
palatal organs or the barbel of carp or catfish. In fact, it has been found
that free chemosensitive nerve endings in the sea robin fin do not respond
to sugars and that spinally innervated chemoreceptors of sea robins
respond to a smaller variety of substances than do the spinally and
cranially innervated fins of the tomcod.
It is not yet clear whether or not different sapid substances react on
selective sites of the chemoreccptors of the tastc cmd organs of the fish.
It is obvious, however, that certain animals such as freshwater carp,
respond maximally to certain stimuli. The palatal nerves respond grossly
to sweet substances. On the other hand, the sea catfish barbel does not
respond at all to sugar substances. It also appears that there is conipctition for sites on the receptor organ and that the balances and synergistic
effects of different substances yield quantativc differences in electrophysiological patterns of dischargc.
E. Audition
In general the experiments on audition can be divided into three
classes. In one, behavioral end points are used to determine the acoustic
threshold of an animal. The second utilizes autonomic unconditioned
responses (heart rate) to obtain audiograms. The last approach is an
electrophysiological approach to the determination of the central nervous
system information used in the integration of acoustic stimuli. The bchavioral work has established that the pars inferior (the sacculus and
lagena) are the chief organs for sound perception in thr tclrost and
vestibular function resides in the pars superior (utriculus and semicircular canals). However, different parts of labyrinthine function have
not been exclusively isolated in the organ so far. In general, members
of the Ostariophysi have much better auditory discrimination than nonostariophysid fish. This is most probably because of thc morphological
connection between the swim bladder and the inner ear through thc
three pairs of Webcrian ossiclchs (Alexander, 1966; Enger, 1963; Healey,
1957; Kleerekoper and Roggcnkamp, 1959; Lowenstcin et al., 1968). Fish
have perceived some frcquencics up to 13,000 Hz, although in most species
the upper hearing limit lies around 5000-7000 Hz and is the approximate