Bipolar, amacrine, and ganglion cells of carp retina, stained intracellularly with Procion yellow, can be divided into types a and b, according to the destination of terminals and dendritic trees in the inner plexiform layer (sublamina a and b, respectively). Type a cells showed hyperpolarizing, or off, responses and type b cells depolarizing, or on, responses. Carp thus resembles cat in the basic organization of on and off pathways in the retina.