Special retinal receptor elements which are presumed to be primarily concerned with perception of light stimuli, when the eye is adapted to darkness.
Note: The rods probably play no part in colour stimulus discrimination (see "scotopic vision", 2-1-335).
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM