Cone mosaics in a teleost retina: Changes during light and dark adaptation

Summary The square mosaic pattern of retinal cones in the guppy,Poecilia reticulata, changes during dark adaptation into a row mosaic. The functional significance of this change is discussed.Thanks are due to Dr A. Yacob, Biology Department, Mosul University, for supplying the photomicrograph for figure 2A, and to Dr C. Wise, Department of Zoology, University College, Dublin, and B. A. Collins, The Marine Biological Laboratory, Woods Hole, for technical assistance.