The spectral absorbances of extracts and of sucrose suspensions of outer segments from three species have been studied. In Rana pipiens the displacement to longer wavelengths which was noted in the difference spectra obtained from cell suspensions as compared to extracts was removed by hydroxylamine. In Plecostomus plecostomus a 5-nm displacement still remained after treatment with hydroxylamine and partial bleaching showed that this was due to a second pigment, possibly from cones, which was not present in extracts. In Gekko gekko no red shift was observed in the P5211. It is concluded that the spectral absorbance of a visual pigment extract is identical to the absorbance of the pigment in situ, and that the displacement to longer wavelengths of the difference spectra obtained from cellular suspensions is primarily due to photoproducts which absorb within the visible region of the spectrum. ?? 1972.
Bowmaker, J. K. (1972). Kundt’s rule: The spectral absorbance of visual pigments in situ and in solution. Vision Research, 12(4), 529–548. https://doi.org/10.1016/0042-6989(72)90149-6