48
T. TOMITA
work on fish but on primate retinas. Under such circumstances, a simple
term “S potential,” abbreviated from Svaetichin’s potential, is now most
commonly used.
The S potentials are classified into two major types from their response patterns to spectral light ( Svaetichin, 1956; MacNichol and
Svaetichin, 1958). Those responding only with hyperpolarization to all
wavelengths of light are called the “luminosity type” ( L response) and
those in which the response polarity is wavelength-dependent are called
the “chromaticity type” ( C response). The C response is further subdivided into Y-B (yellow-blue) type and R-G (red-green) type. Examples of these responses are illustrated in Fig. 11. The Lutianidae and
other species collected in water 30 to 70 meters deep gave only an L response that had a peak toward the blue end of the spectrum. Of the
shallow water fishes, the mullet, Mugil, gave both the R-G and Y-B
responses in addition to the L response, but the Serranidae gave L and
a
I
.
,
.
,
.
,
.
Fig. 11. Response spectra of S potentials from retinas belonging to different
families. ( 1 ) Lutianidae (achromatic vision), which live deeper than 30 meters,
giving only L responses with peak at about 490 mp. ( 2 ) Serranidae (dichromatic
vision), giving both L and Y-B responses. ( 3 ) Centropomidae ( dichromatic vision ),
giving both L and R-G responses. (4) Mugilidae, giving all three types of response.
The fishes used to make records 2-4 were all caught in very shallow water. From
MacNichol and Svaetichin (1958).