To examine further the behavior of the gecko visual pigments to anions and to compare this behavior in extracts and with the pigment in situ within the cell. Also to inquire as to why gecko pigments are labile to temperature, to -SH reagents and to anions whereas rhodopsins are not. To examine further by means of microspectrophotometry the visual cells of nocturnal geckos, of diurnal geckos and of diurnal lizards. To examine the gecko retina for an e-wave and to assay whether or not the absence of an M-III intermediate in the gecko can be used to assay the role of the M-III in generating the e-wave in the frog retina. To study further the possible effects of iodides on the properties of the visual pigments of geckos and other vertebrates. BIBLIOGRAPHIC REFERENCES: Crescitelli, F. (1975). The gecko visual pigments. II: Color and the sulfhydryl group. Vision Research 15, 743-745. Crescitelli, F. (1975). The gecko visual pigments: ionic effects on color. Abstract, 26th Annual Fall Meeting, American Physiol. Society, October 5-10, l975.