“…First, the negative response transients to a small light spot centred in the neighbourhood of the electrode is comparable to the PNR of the inner plexiform layer as reported in other species (Ogden, 1973;Proenza & Burkhardt, 1973;Burkhardt, 1970) and confirms earlier observations in this laboratory, including a lack of polarity inversion with electrode depth (Holden, 1972). We have not, however, been able to substantiate a polarity inversion accompanying annular stimulation as recently reported in the mudpuppy (Proenza & Burkhardt, 1973) and therefore cannot offer evidence that the generators of the centre-based PNR are tangentially oriented in the retina. Secondly, and in contrast to the mudpuppy findings, the response wate form which we measure to an annulus has a prominent negative component.…”