Abstract
Certain ganglion cells from the central region of dark-adapted retina of the rhesus monkey respond to stimulation of both rod and cone receptors. With dim stimuli the function of these ganglion cells is determined entirely by the rods; with brighter stimuli that affect both dark-adapted rods and cones, little evidence of rod function is detectable because a cone mechanism appears to determine both the latency and frequency of ganglion-cell firing.